User:Kazkaskazkasako/Books/Physical sciences

Physical sciences (PhysSci):
 * Physics
 * Particle physics
 * Chemistry
 * Astronomy
 * Earth sciences
 * Environment


 * Cosmic Calendar.png

Metrology, metric system

 * Category:Metrology
 * Category:Metric system
 * Category:International System of Units
 * Category:SI units
 * Category:Physical quantities
 * Category:Systems of units
 * Category:Units of mass
 * Category:Scientific observation
 * Category:Measurement
 * Category:Metrology


 * MKS system of units: physical system of measurement that uses the metre, kilogram, and second (MKS) as base units; forms the base of the SI.
 * International System of Units (SI, French: Système international (d'unités)): modern form of the metric system. It is the only system of measurement with an official status in nearly every country in the world. It comprises a coherent system of units of measurement starting with seven base units, which are the second (the unit of time with the symbol s), metre (length, m), kilogram (mass, kg), ampere (electric current, A), kelvin (thermodynamic temperature, K), mole (amount of substance, mol), and candela (luminous intensity, cd). The system allows for an unlimited number of additional units, called derived units, which can always be represented as products of powers of the base units. Twenty-two derived units have been provided with special names and symbols. The seven base units and the 22 derived units with special names and symbols may be used in combination to express other derived units, which are adopted to facilitate measurement of diverse quantities. The SI system also provides twenty prefixes to the unit names and unit symbols that may be used when specifying power-of-ten (i.e. decimal) multiples and sub-multiples of SI units. The SI is intended to be an evolving system; units and prefixes are created and unit definitions are modified through international agreement as the technology of measurement progresses and the precision of measurements improves.
 * Metric prefix: unit prefix that precedes a basic unit of measure to indicate a multiple or fraction of the unit. While all metric prefixes in common use today are decadic, historically there have been a number of binary metric prefixes as well. Each prefix has a unique symbol that is prepended to the unit symbol. New in 2022: ronna R 10²⁷ & quetta Q 10³⁰; ronto r 10⁻²⁷ & quecto q 10⁻³⁰.
 * Centimetre–gram–second system of units (CGS, cgs): variant of the metric system based on the centimetre as the unit of length, the gram as the unit of mass, and the second as the unit of time. All CGS mechanical units are unambiguously derived from these three base units, but there are several different ways in which the CGS system was extended to cover electromagnetism.
 * Metre Convention (Treaty of the Metre): international treaty that was signed in Paris on 1875.05.20 by representatives of 17 nations (Argentina, Austria-Hungary, Belgium, Brazil, Denmark, France, Germany, Italy, Peru, Portugal, Russia, Spain, Sweden and Norway, Switzerland, Ottoman Empire, USA, and Venezuela). The treaty created BIPM, an intergovernmental organization under the authority of CGPM and the supervision of CIPM, that coordinates international metrology and the development of the metric system.
 * International Bureau of Weights and Measures (BIPM; French: Bureau international des poids et mesures): intergovernmental organisation that was established by the Metre Convention, through which member states act together on matters related to measurement science and measurement standards (i.e. the SI).
 * General Conference on Weights and Measures (French: Conférence Générale des Poids et Mesures, abbreviated CGPM): supreme authority of BIPM, the inter-governmental organization established in 1875 under the terms of the Metre Convention through which Member States act together on matters related to measurement science and measurement standards. The CGPM is made up of delegates of the governments of the Member States and observers from the Associates of the CGPM. Under its authority, the International Committee for Weights and Measures (ICWM) (French: Comité international des poids et mesures (CIPM)) executes an exclusive direction and supervision of the BIPM.


 * History of the metre: starts with the scientific revolution that began with Nicolaus Copernicus's work in 1543. Increasingly accurate measurements were required, and scientists looked for measures that were universal and could be based on natural phenomena rather than royal decree or physical prototypes. Rather than the various complex systems of subdivision in use, they also preferred a decimal system to ease their calculations. With the French Revolution (1789) came a desire to replace many features of the Ancien Régime, including the traditional units of measure. As a base unit of length, many scientists initially favored the seconds pendulum (a pendulum with a half-period of one second), but this was rejected when it was discovered that it varied from place to place with local gravity. A new unit of length, the metre was introduced - defined as one ten-millionth of the distance from the North Pole to the equator. For practical purposes however, the standard metre was made available in the form of a platinum bar held in Paris. This in turn was replaced in 1889 by thirty platinum-iridium bars kept across the globe. However, using such physical objects as the standard had been something that the original definition had aimed to avoid, so in 1960 a new definition based on a specific number of wavelengths of light from a specific transition in krypton-86 allowed the standard to be universally available by measurement.
 * Anglo-French Survey (1784–1790): to measure the relative situation of Greenwich Observatory and the Paris Observatory. The English operations, executed by William Roy, consisted of the measurements of bases at Hounslow Heath (1784) and Romney Marsh (1787), the measurements of the angles of the triangles (1787–1788) and finally the calculation of all the triangles (1788–1790).
 * Ordnance Survey: national mapping agency of the United Kingdom which covers the island of Great Britain.
 * Ramsden surveying instruments (five great theodolites)


 * Troy weight: system of units of mass that originated in 15th-century England, and is primarily used in the precious metals industry. The Troy weights are the grain, the pennyweight (24 grains), the troy ounce (20 pennyweights), and the troy pound (12 troy ounces). Many aspects of the troy weight system were indirectly derived from the Roman monetary system. 1 troy ounce (oz t) = 31.1034768 g.


 * Tito Livio Burattini (Polish: Tytus Liwiusz Burattini, 1617.03.08–1681.11.17): inventor, architect, Egyptologist, scientist, instrument-maker, traveller, engineer, and nobleman, who spent his working life in Poland and Lithuania. He was born in Agordo, Italy, and studied in Padua and Venice. In 1639, he explored the Great Pyramid of Giza with English mathematician John Greaves; both Burattini and Sir Isaac Newton used measurements made by Greaves in an attempt to accurately determine the circumference of the earth. In 1641, the court of King Władysław IV invited him to Poland. In Warsaw, Burattini built a model aircraft with four fixed glider wings in 1647. He later developed an early system of measurement based on time, similar to today's International System of Units; he published it in his book Misura universale (lit. "universal measure") in 1675 at Vilnius. His system includes the metro cattolico (lit. "catholic [i.e. universal] metre"), a unit of length equivalent to the length of a free seconds pendulum; it differs from the modern metre by half a centimetre. He is considered the first to recommend the name metre for a unit of length.


 * 2019 redefinition of the SI base units: in 2019, four of the seven SI base units specified in the International System of Quantities were redefined in terms of natural physical constants, rather than human artifacts such as the standard kilogram. Effective 2019.05.20, the 144th anniversary of the Metre Convention, the kilogram, ampere, kelvin, and mole are now defined by setting exact numerical values, when expressed in SI units, for the Planck constant ($h$), the elementary electric charge ($e$), the Boltzmann constant ($k_{B}$), and the Avogadro constant ($N_{A}$), respectively. The second, metre, and candela had previously been redefined using physical constants. The four new definitions aimed to improve the SI without changing the value of any units, ensuring continuity with existing measurements.

Physical properties, Physical quantities, Chemical properties

 * Category:Chemical properties
 * Category:Physical quantities
 * Category:Mass


 * Template:Mole concepts
 * Template:Chemical solutions


 * Mole (unit): defined as the amount of a chemical substance that contains as many elementary entities, e.g., atoms, molecules, ions, electrons, or photons, as there are atoms in 12 grams of carbon-12 (12C), the isotope of carbon with relative atomic mass 12 by definition. This number is expressed by the Avogadro constant, which has a value of $6.022 mol^{-1}$. History of the mole is intertwined with that of molecular mass, atomic mass unit, Avogadro's number and related concepts.
 * Equivalent weight
 * Dalton (unit) (unified atomic mass unit; Da, u): unit of mass widely used in physics and chemistry. It is defined as $1/12$ of the mass of an unbound neutral atom of carbon-12 in its nuclear and electronic ground state and at rest. The atomic mass constant, denoted mu is defined identically, giving mu = m($12$C)/12 = 1 Da. A unit dalton is also approximately numerically equal to the molar mass of the same expressed in grams per mole ($N_{A} Da ≈ 1 g/mol$). Prior to the 2019 redefinition of the SI base units these were numerically identical by definition ($N_{A} Da = 1 g/mol$) and are still treated as such for most purposes.


 * Molar concentration (molarity, substance concentration): measure of the concentration of a solute in a solution, or of any chemical species, in terms of amount of substance in a given volume. A commonly used unit for molar concentration used in chemistry is mol/L. A solution of concentration 1 mol/L is also denoted as 1 molar (1 M).
 * Molar mass (M): physical property defined as the mass of a given substance (chemical element or chemical compound) divided by its amount of substance. The base SI unit for molar mass is kg/mol. However, for historical reasons, molar masses are almost always expressed in g/mol.
 * Molality (molal concentration): measure of the concentration of a solute in a solution in terms of amount of substance in a specified amount of mass of the solvent. This contrasts with the definition of molarity which is based on a specified volume of solution.

Time, date

 * Category:Time
 * Category:Time in science
 * Category:Time in physics
 * Category:Time travel
 * Category:Units of time

{q.v. }
 * 
 * 


 * Time: continued sequence of existence and events that occurs in an apparently irreversible succession from the past, through the present, into the future. It is a component quantity of various measurements used to sequence events, to compare the duration of events or the intervals between them, and to quantify rates of change of quantities in material reality or in the conscious experience. Time is often referred to as a fourth dimension, along with three spatial dimensions.
 * Time in physics: defined by its measurement: time is what a clock reads. In classical, non-relativistic physics, it is a scalar quantity (often denoted by the symbol $$t$$) and, like length, mass, and charge, is usually described as a fundamental quantity. Time can be combined mathematically with other physical quantities to derive other concepts such as motion, kinetic energy and time-dependent fields. Timekeeping is a complex of technological and scientific issues, and part of the foundation of recordkeeping. Conceptions of time: Regularities in nature (Mechanical clocks); Galileo: the flow of time; Newton's physics: linear time; Thermodynamics and the paradox of irreversibility; Electromagnetism and the speed of light; Einstein's physics: spacetime; Time in quantum mechanics.
 * Arrow of time (time's arrow): concept positing the "one-way direction" or "asymmetry" of time. It was developed in 1927 by the British astrophysicist Arthur Eddington, and is an unsolved general physics question. This direction, according to Eddington, could be determined by studying the organization of atoms, molecules, and bodies, and might be drawn upon a four-dimensional relativistic map of the world ("a solid block of paper"). Physical processes at the microscopic level are believed to be either entirely or mostly time-symmetric: if the direction of time were to reverse, the theoretical statements that describe them would remain true. Yet at the macroscopic level it often appears that this is not the case: there is an obvious direction (or flow) of time. In the 1928 book The Nature of the Physical World, which helped to popularize the concept, Eddington stated:

"Let us draw an arrow arbitrarily. If as we follow the arrow we find more and more of the random element in the state of the world, then the arrow is pointing towards the future; if the random element decreases the arrow points towards the past. That is the only distinction known to physics. This follows at once if our fundamental contention is admitted that the introduction of randomness is the only thing which cannot be undone. I shall use the phrase 'time's arrow' to express this one-way property of time which has no analogue in space.". Arrows: Thermodynamic arrow of time; Cosmological arrow of time; Radiative arrow of time; Causal arrow of time; Particle physics (weak) arrow of time; Quantum arrow of time; Psychological/perceptual arrow of time.


 * Year: orbital period of a planetary body, for example, the Earth, moving in its orbit around the Sun. Due to the Earth's axial tilt, the course of a year sees the passing of the seasons, marked by change in weather, the hours of daylight, and, consequently, vegetation and soil fertility. In temperate and subpolar regions around the planet, four seasons are generally recognized: spring, summer, autumn and winter. In tropical and subtropical regions, several geographical sectors do not present defined seasons; but in the seasonal tropics, the annual wet and dry seasons are recognized and tracked. A calendar year is an approximation of the number of days of the Earth's orbital period, as counted in a given calendar. The Gregorian calendar, or modern calendar, presents its calendar year to be either a common year of 365 days or a leap year of 366 days, as do the Julian calendars. For the Gregorian calendar, the average length of the calendar year (the mean year) across the complete leap cycle of 400 years is 365.2425 days.
 * Abbreviations yr and ya: kyr (kilo years) - SI: ka; myr, Myr (million years, Mega years) - SI: Ma; byr (billion years) - SI: Ga; kya (kilo years ago) - SI: ka ago; mya, Mya (million years ago, Mega years ago) - SI: Ma ago; bya, Gya (billion years ago, giga years ago) - SI: Ga ago.


 * Timeline of the far future: present understanding in various fields allows for the prediction of far future events, if only in the broadest strokes. These fields include astrophysics, which has revealed how planets and stars form, interact, and die; particle physics, which has revealed how matter behaves at the smallest scales; evolutionary biology, which predicts how life will evolve over time; and plate tectonics, which shows how continents shift over millennia. The timelines displayed here cover events from roughly eight thousand years from now to the furthest reaches of future time.


 * Adoption of the Gregorian calendar
 * Old Style and New Style dates


 * Closed timelike curve (CTC): world line in a Lorentzian manifold, of a material particle in spacetime, that is "closed", returning to its starting point. This possibility was first discovered by Willem Jacob van Stockum in 1937 and later confirmed by Kurt Gödel in 1949, who discovered a solution to the equations of general relativity (GR) allowing CTCs known as the Gödel metric; and since then other GR solutions containing CTCs have been found, such as the Tipler cylinder and traversable wormholes. If CTCs exist, their existence would seem to imply at least the theoretical possibility of time travel backwards in time, raising the spectre of the grandfather paradox, although the Novikov self-consistency principle seems to show that such paradoxes could be avoided. Some physicists speculate that the CTCs which appear in certain GR solutions might be ruled out by a future theory of quantum gravity which would replace GR, an idea which Stephen Hawking labeled the chronology protection conjecture. Others note that if every closed timelike curve in a given space-time passes through an event horizon, a property which can be called chronological censorship, then that space-time with event horizons excised would still be causally well behaved and an observer might not be able to detect the causal violation.

Timekeeping, horology

 * Category:Timekeeping
 * Category:Chronology
 * Category:Dating methods
 * Category:Units of time
 * Category:Names of units of time
 * Category:Horology


 * Horology: are or science of measuring time. Clocks, watches, clockwork, sundials, clepsydras, timers, time recorders and marine chronometers are all examples of instruments used to measure time.


 * Common Era: Internet reaction: According to a Los Angeles Times report, it was a student's use of BCE/CE notation, inspired by its use within Wikipedia, which prompted the history teacher Andrew Schlafly to found Conservapedia, a cultural conservative wiki.


 * Roman calendar
 * Julian calendar: reform of the Roman calendar introduced by Julius Caesar in 46 BC (708 AUC); took effect in 45 BC (709 AUC); was the predominant calendar in most of Europe, and in European settlements in the Americas and elsewhere. Superseded by Gregorian calendar. 365 d. = 12 months, leap day is added to February every 4 y (Julian year on average=365.25 d.) . Julian calendar is still used by the Berber people of North Africa and on Mount Athos; in the form of the Alexandrian calendar, it is the basis for the Ethiopian calendar, which is the civil calendar of Ethiopia; Eastern Orthodox Church branches.
 * Gregorian calendar (Western calendar, Christian calendar): internationally the most widely used civil calendar. It is named for Pope Gregory XIII, who introduced it in 1582. The calendar was a refinement in 1582 to the Julian calendar amounting to a 0.002% correction in the length of the year. The motivation for the reform was to bring the date for the celebration of Easter to the time of the year in which the First Council of Nicaea had agreed upon in 325. Because the celebration of Easter was tied to the spring equinox, the Roman Catholic Church considered this steady drift in the date of Easter undesirable. The Gregorian calendar therefore began by skipping 10 calendar days, to restore 21 March as the date of the vernal equinox.
 * Proleptic Gregorian calendar: is produced by extending the Gregorian calendar backward to dates preceding its official introduction in 1582.
 * Old Style and New Style dates
 * Dual dating: e.g., in "10/21 February 1750/51", the dual day of the month is due to the leap year correction of the Julian calendar by the Gregorian calendar, and the dual year is due to some countries beginning their numbered year on 1 January while others were still using another date.
 * ISO 8601 (Data elements and interchange formats – Information interchange – Representation of dates and times; 1988): international standard covering the exchange of date and time-related data. Purpose of this standard is to provide an unambiguous and well-defined method of representing dates and times, so as to avoid misinterpretation of numeric representations of dates and times, particularly when data are transferred between countries with different conventions for writing numeric dates and times.


 * 0 (year): does not exist in the Anno Domini/Common Era system usually used to number years in the Gregorian calendar and in its predecessor, the Julian calendar . In this system, the year 1 BC is followed by AD 1. However, there is a year zero in astronomical year numbering (where it coincides with the Julian year 1 BC) and in ISO 8601:2004 (where it coincides with the Gregorian year 1 BC) as well as in all Buddhist and Hindu calendars.
 * Astronomical year numbering: based on AD/CE year numbering, but follows normal decimal integer numbering more strictly. Thus, it has a year 0, the years before that are designated with negative numbers and the years after that are designated with positive numbers. Astronomers use the Julian calendar for years before 1582, including this year 0, and the Gregorian calendar for years after 1582 as exemplified by Jacques Cassini (1740), Simon Newcomb (1898) and Fred Espenak (2007).
 * Before Present (BP): years is a time scale used mainly in geology and other scientific disciplines to specify when events in the past occurred. Because the "present" time changes, standard practice is to use 1 January 1950 as commencement date of the age scale, reflecting the fact that radiocarbon dating became practicable in the 1950s. The abbreviation "BP", with the same meaning, has also been interpreted as "Before Physics" ; that is, before nuclear weapons testing artificially altered the proportion of the carbon isotopes in the atmosphere, making dating after that time likely to be unreliable.


 * Julian day: continuous count of days since the beginning of the Julian Period used primarily by astronomers; starting from noon Greenwich Mean Time, with Julian day number 0 assigned to the day starting at noon on January 1, 4713 BC, proleptic Julian calendar.


 * Names of the days of the week: time unit equal to seven days. It is the standard time period used for cycles of rest days in most parts of the world, mostly alongside—although not strictly part of—the Gregorian calendar. In many languages, the days of the week are named after classical planets or gods of a pantheon. Planetary week
 * Names of the days of the week


 * Chinese calendar:
 * History
 * Structure: Week: As early as the Bronze-Age Xia dynasty, days were grouped into nine- or ten-day weeks known as xún (旬). Months consisted of three xún. The first 10 days were the early xún (上旬), the middle 10 the mid xún (中旬), and the last nine (or 10) days were the late xún (下旬). Japan adopted this pattern, with 10-day-weeks known as jun (旬). In Korea, they were known as sun (순,旬). The structure of xún led to public holidays every five or ten days. During the Han dynasty, officials were legally required to rest every five days (twice a xún, or 5–6 times a month). The name of these breaks became huan (澣; 浣, "wash"). The seven-day week was adopted from the Hellenistic system by the 4th century CE, although its source is unclear. It was again transmitted to China in the 8th century by Manichaeans via Kangju (a Central Asian kingdom near Samarkand), and is the most-used system in modern China.
 * Chinese calendar correspondence table


 * ΔT (timekeeping) (Delta T): measure of the cumulative effect of the departure of the Earth's rotation period from the fixed-length day of International Atomic Time (86,400 seconds). Formally, ΔT is the time difference ΔT = TT − UT between Universal Time (UT, defined by Earth's rotation) and Terrestrial Time (TT, independent of Earth's rotation). The value of ΔT for the start of 1902 was approximately zero; for 2002 it was about 64 seconds.

Physical sciences

 * Category:Physical sciences
 * Category:Applied and interdisciplinary physics
 * Category:Biophysics
 * Category:Materials science
 * Category:Physical chemistry


 * Parts-per notation: ppm (parts-per-million, 10–6), ppb (parts-per-billion, 10–9), ppt (parts-per-trillion, 10–12) and ppq (parts-per-quadrillion, 10-15). ppX arises from mol/mol, kg/kg, L/L etc; dimensionless quantities.


 * Solvay Conference (Congrès Solvay): have been devoted to outstanding preeminent open problems in both physics and chemistry. They began with the historic invitation-only 1911 Solvay Conference on Physics, considered a turning point in the world of physics, and continue to the present day.



Instrumental analysis

 * Category:Instrumental analysis
 * Category:Mass spectrometry
 * Category:Spectroscopy


 * Ultraviolet–visible spectroscopy (ultraviolet-visible spectrophotometry; UV-Vis or UV/Vis): absorption spectroscopy or reflectance spectroscopy in the ultraviolet-visible spectral region. This means it uses light in the visible and adjacent (near-UV and near-infrared [NIR]) ranges. The absorption or reflectance in the visible range directly affects the perceived color of the chemicals involved. In this region of the electromagnetic spectrum, atoms and molecules undergo electronic transitions. Absorption spectroscopy is complementary to fluorescence spectroscopy, in that fluorescence deals with transitions from the excited state to the ground state, while absorption measures transitions from the ground state to the excited state.


 * Mass spectrometry: analytical technique that produces spectra of the masses of the atoms or molecules comprising a sample of material; used to determine the elemental or isotopic signature of a sample, the masses of particles and of molecules, and to elucidate the chemical structures of molecules, such as peptides and other chemical compounds. Mass spectrometry works by ionizing chemical compounds to generate charged molecules or molecule fragments and measuring their mass-to-charge ratios. The use of the term mass spectroscopy is now discouraged due to the possibility of confusion with light spectroscopy.
 * Atmospheric-pressure chemical ionization (APCI): ionization method used in mass spectrometry which utilizes gas-phase ion-molecule reactions at atmospheric pressure (10⁵ Pa), commonly coupled with HPLC. APCI is a soft ionization method similar to chemical ionization where primary ions are produced on a solvent spray. The main usage of APCI is for polar and relatively less polar thermally stable compounds with molecular weight less than 1500 Da. eluate flows at 0.2 to 2.0 mL/min into a pneumatic nebulizer which creates a mist of fine droplets. Droplets are vaporized by impact with the heated walls at 350-500℃ and carried by the nebulizer gas and an auxiliary gas into the ion molecule reaction region between the corona electrode and the exit counter-electrode. A constant current of 2-5 µA is maintained from the corona needle.  Sample ions are produced by ion-molecule reactions, and pass through a small orifice or tube into the ion transfer region leading to the mass spectrometer.
 * Ionization mechanism: sample in solution, sample vapor, and sample ions. The effluent from the HPLC is evaporated completely. The mixture of solvent and sample vapor is then ionized by ion-molecule reaction. In the positive mode, the relative proton affinities of the reactant ions and the gaseous analyte molecules allow either proton transfer or adduction of reactant gas ions to produce the ions [M+H]⁺ of the molecular species. In the negative mode, [M−H]⁻ ions are produced by either proton abstraction, or [M+X]⁻ ions are produced by anion attachment. Most work on the APCI-MS analysis has been in positive mode. Primary and secondary reagent ion formation in a nitrogen atmosphere in the presence of water:
 * N2 + e → N2+ + 2e
 * N2+* + 2N2 → N4+* + N2
 * N4+ + H2O → H2O+ + 2N2
 * H2O+ + H2O → H3O+ + OH•
 * H3O+ + H2O + N2 → H+(H2O)2 + N2
 * H+(H2O)n-1 + H2O + N2 → H+(H2O)n + N2

Ionization of product ions:
 * H+(H2O)n + M → MH+(H2O)m + (n-m)H2O

Declustering in the high vacuum of the mass analyzer:
 * MH+(H2O)m → MH+ + mH2O
 * Electrospray ionization (ESI): technique used in mass spectrometry to produce ions using an electrospray in which a high voltage is applied to a liquid to create an aerosol. It is especially useful in producing ions from macromolecules because it overcomes the propensity of these molecules to fragment when ionized. effectively extending the mass range of the analyser to accommodate the kDa-MDa orders of magnitude observed in proteins and their associated polypeptide fragments. Mass spectrometry using ESI is called electrospray ionization mass spectrometry (ESI-MS) or, less commonly, electrospray mass spectrometry (ES-MS). ESI is a so-called 'soft ionization' technique, since there is very little fragmentation.

Amorphous phase (glass)

 * Category:Glassforming liquids and melts
 * Category:Glass
 * Category:Glass types


 * Glass transition temperature
 * Vitrification
 * Ice: Phases: Atmospheric pressure=105 Pa; Ic (cubic ice), Ih (hexagonal ice).
 * Amorphous ice: Low-density amorphous ice (LDA, vapor-deposited amorphous water ice, amorphous solid water (ASW), hyperquenched glassy water (HGW)) - density=0.94 g/cm3; High-density amorphous ice (HDA) - density=1.17 g/cm3; Very-high-density amorphous ice (VHDA) - density=1.26 g/cm3.


 * Prince Rupert's drop: toughened glass beads created by dripping molten glass into cold water, which causes it to solidify into a tadpole-shaped droplet with a long, thin tail. These droplets are characterized internally by very high residual stresses, which give rise to counter-intuitive properties, such as the ability to withstand a blow from a hammer or a bullet on the bulbous end without breaking, while exhibiting explosive disintegration if the tail end is even slightly damaged. In nature, similar structures are produced under certain conditions in volcanic lava, and are known as Pele's tears. The explosive disintegration arises due to multiple crack bifurcation events when the tail is cut – a single crack is accelerated in the tensile residual stress field in the center of the tail and bifurcates after it reaches a critical velocity of 1,450–1,900 m/s. Given these high speeds, the disintegration process due to crack bifurcation can only be inferred by looking into the tail and employing high speed imaging techniques. This is perhaps why this curious property of the drops remained unexplained for centuries. The second unusual property of the drops, namely the strength of the heads, is a direct consequence of large compressive residual stresses —up to 700 megapascals (100,000 psi)— that exist in the vicinity of the head's outer surface. This stress distribution is measured by using glass's natural property of stress-induced birefringence and by employing techniques of 3D photoelasticity. The high fracture toughness due to residual compressive stresses makes Prince Rupert's drops one of the earliest examples of toughened glass.

What is life? How cells and their contents work
{q.v. }
 * User:Kazkaskazkasako/Books/All
 * User:Kazkaskazkasako/Work
 * User:Kazkaskazkasako/Work
 * User:Kazkaskazkasako/Books/EECS

Life is a learning system. Different spacetime scales for learning - evolutionary (slowest), neuronal/brain (memory, pattern recognition, reasoning, intelligence), machine learning (fastest). Media: DNA&RNA-protein-cells-cell connections-electrochemical impulses, electrical impulses-RAM-HDD&SSD-semiconductors, quantum computers-quantum states, analog computers.


 * Brownian motor: nano-scale or molecular devices by which thermally activated processes (chemical reactions) are controlled and used to generate directed motion in space and to do mechanical or electrical work
 * Fluctuation Theorem: (from statistical mechanics) relative probability that the entropy of a system which is currently away from thermodynamic equilibrium (i.e., away from maximum entropy) will increase or decrease over a given amount of time
 * Entropy and life
 * Microcanonical ensemble

Origin of life, abiogenesis

 * Category:Origin of life
 * Category:Astrobiology

{q.v. User:Kazkaskazkasako/Work}


 * Shock synthesis: process of complex organic chemical creation through high velocity impact on simple amino acids, theorized to take place when a comet strikes a planetary body, or through the shock-wave created by a thunder clap. Hyper-velocity impact shock of a typical comet ice mixture produced several amino acids after hydrolysis. These include equal amounts of D- and L-alanine, and the non-protein amino acids α-aminoisobutyric acid and isovaline as well as their precursors.

Physics

 * Category:Physics
 * Category:Concepts in physics
 * Category:Physical quantities
 * Category:Physical constants
 * Category:Fundamental constants

Template:Physical constants: easy inclusion of the latest CODATA recommended values of physical constants in articles. It gives the most recent values published, and will be updated when newer values become available, which is typically every four years.


 * Point particle (ideal particle): idealization of particles heavily used in physics. Its defining feature is that it lacks spatial extension; being dimensionless, it does not take up space. A point particle is an appropriate representation of any object whenever its size, shape, and structure are irrelevant in a given context. For example, from far enough away, any finite-size object will look and behave as a point-like object. Point masses and point charges, discussed below, are two common cases. When a point particle has an additive property, such as mass or charge, it is often represented mathematically by a Dirac delta function.

The essence:
 * Conservation law


 * Symmetry in physics
 * CP violation


 * Noether's theorem


 * Continuity equation, but what if digitalism and quanta in everything is true? Is it still possible to apply differentiation and integration?


 * Periodic tables (Template:PeriodicTablesFooter)
 * Table of nuclides, Table of nuclides (combined)


 * Natural units: physical units of measurement based only on universal physical constants. Purely natural system of units is defined in such a way that some set of selected universal physical constants are normalized to unity.


 * Dimensionless physical constant: pure number having no units attached and having a numerical value that is independent of whatever system of units may be used. Fundamental physical constant is used to refer to some universal dimensionless constants. Perhaps the best-known example is the fine-structure constant, α, which has an approximate value of $1/137.03599908$. The correct use of the term fundamental physical constant should be restricted to the dimensionless universal physical constants that currently cannot be derived from any other source. However, the term fundamental physical constant has been sometimes used to refer to certain universal dimensioned physical constants, such as the speed of light c, vacuum permittivity ε0, Planck constant h, and the gravitational constant G, that appear in the most basic theories of physics. NIST and CODATA sometimes used the term in this way in the past.
 * Characteristics: the Standard Model requires 25 physical constants, about half of them the masses of fundamental particles (which become "dimensionless" when expressed relative to the Planck mass or, alternatively, as coupling strength with the Higgs field along with the gravitational constant). Fundamental physical constants cannot be derived and have to be measured. Developments in physics may lead to either a reduction or an extension of their number: discovery of new particles, or new relationships between physical phenomena, would introduce new constants, while the development of a more fundamental theory might allow the derivation of several constants from a more fundamental constant. A long-sought goal of theoretical physics is to find first principles ("Theory of Everything") from which all of the fundamental dimensionless constants can be calculated and compared to the measured values.
 * Fine structure constant
 * Proton-to-electron mass ratio (μ or β): simply the rest mass of the proton (a baryon found in atoms) divided by that of the electron (a lepton found in atoms) μ = . Variation of μ over time.


 * Coupling constant

Theoretical physics

 * Category:Theoretical physics
 * Category:Mathematical physics
 * Category:Statistical mechanics
 * Category:Quantum field theory


 * Sign convention: choice of the physical significance of signs (plus or minus) for a set of quantities, in a case where the choice of sign is arbitrary. "Arbitrary" here means that the same physical system can be correctly described using different choices for the signs, as long as one set of definitions is used consistently. The choices made may differ between authors. In general, a sign convention is a special case of a choice of coordinate system for the case of one dimension.
 * In relativity, the metric signature can be either (+,−,−,−) or (−,+,+,+).


 * Canonical commutation relation: fundamental relation between canonical conjugate quantities (quantities which are related by definition such that one is the Fourier transform of another).

$$[\hat x,\hat p_x] = i\hbar \mathbb{I}$$, $$ \mathbb{I}$$ is the unit operator
 * Relation to classical mechanics: Derivation from Hamiltonian mechanics
 * The Weyl relations
 * Generalizations
 * Gauge invariance
 * Uncertainty relation and commutators
 * Uncertainty relation for angular momentum operators

Quantum mechanics (QM)

 * Category:Quantum mechanics
 * Category:Quantum chemistry
 * Category:Quantum electronics
 * Category:Quantum electrodynamics
 * Category:Quantum field theory: Canonical quantization {q.v. User:Kazkaskazkasako/Books/Mathematics}
 * Category:Anomalies (physics)
 * Category:Quantum chromodynamics
 * Category:Standard Model
 * Category:String theory
 * Category:Pauli exclusion principle
 * Category:Schrödinger equation
 * Category:Thought experiments in quantum mechanics


 * Template:Quantum field theory


 * Matrix mechanics: formulation of quantum mechanics created by Werner Heisenberg, Max Born, and Pascual Jordan in 1925. It was the first conceptually autonomous and logically consistent formulation of quantum mechanics. Its account of quantum jumps supplanted the Bohr model's electron orbits. It did so by interpreting the physical properties of particles as matrices that evolve in time. It is equivalent to the Schrödinger wave formulation of quantum mechanics, as manifest in Dirac's bra–ket notation.
 * Development of matrix mechanics: Epiphany at Helgoland: In 1925.06.07, after weeks of failing to alleviate his hay fever with aspirin and cocaine, Heisenberg left for the pollen-free North Sea island of Helgoland. While there, in between climbing and memorizing poems from Goethe's West-östlicher Diwan, he continued to ponder the spectral issue and eventually realised that adopting non-commuting observables might solve the problem.
 * The three fundamental papers: After Heisenberg returned to Göttingen, he showed Wolfgang Pauli his calculations, commenting at one point: "Everything is still vague and unclear to me, but it seems as if the electrons will no more move on orbits."


 * Basic concepts of quantum mechanics
 * List of quantum mechanical systems with analytical solutions a useful list


 * Quantum electrodynamics (QED): relativistic quantum field theory of electrodynamics. In essence, it describes how light and matter interact and is the first theory where full agreement between quantum mechanics and special relativity is achieved. QED mathematically describes all phenomena involving electrically charged particles interacting by means of exchange of photons and represents the quantum counterpart of classical electromagnetism giving a complete account of matter and light interaction.


 * Schrödinger equation: linear partial differential equation that governs the wave function of a quantum-mechanical system. Its discovery was a significant landmark in the development of quantum mechanics. The equation is named after Erwin Schrödinger, who postulated the equation in 1925 and published it in 1926, forming the basis for the work that resulted in his Nobel Prize in Physics in 1933.


 * Vacuum polarization: process in which a background electromagnetic field produces virtual electron–positron pairs that change the distribution of charges and currents that generated the original electromagnetic field. It is also sometimes referred to as the self-energy of the gauge boson (photon).


 * Casimir effect: physical forces arising from a quantized field. Typical example is of two uncharged metallic plates in a vacuum, placed a few nanometers apart. In a classical description, the lack of an external field also means that there is no field between the plates, and no force would be measured between them. When this field is instead studied using the QED vacuum of quantum electrodynamics, it is seen that the plates do affect the virtual photons which constitute the field, and generate a net force—either an attraction or a repulsion depending on the specific arrangement of the two plates.


 * History of string theory
 * M-theory: theory in physics that unifies all consistent versions of superstring theory. The existence of such a theory was first conjectured by Edward Witten at a string theory conference at the University of Southern California in the spring of 1995.


 * Holographic principle: property of string theories and a supposed property of quantum gravity that states that the description of a volume of space can be thought of as encoded on a boundary to the region—preferably a light-like boundary like a gravitational horizon.


 * Quantum chromodynamics (QCD): theory of strong interactions, a fundamental force describing the interactions between quarks and gluons which make up hadrons such as the proton, neutron and pion. QCD is a type of quantum field theory called a non-abelian gauge theory with symmetry group SU(3). The QCD analog of electric charge is a property called color. Gluons are the force carrier of the theory, like photons are for the electromagnetic force in quantum electrodynamics.
 * EMC effect: surprising observation that the cross section for deep inelastic scattering from an atomic nucleus is different from that of the same number of free protons and neutrons (collectively referred to as nucleons). From this observation, it can be inferred that the quark momentum distributions in nucleons bound inside nuclei are different from those of free nucleons. This effect was first observed in 1983 at CERN by the European Muon Collaboration, hence the name "EMC effect".


 * One-electron universe: postulate, proposed by John Wheeler in a telephone call to Richard Feynman in the spring of 1940, is the hypothesis that all electrons and positrons are actually manifestations of a single entity moving backwards and forwards in time. According to Feynman: I received a telephone call one day at the graduate college at Princeton from Professor Wheeler, in which he said, "Feynman, I know why all electrons have the same charge and the same mass" "Why?" "Because, they are all the same electron!"


 * CPT symmetry (Charge, parity, and time reversal symmetry): fundamental symmetry of physical laws under the simultaneous transformations of charge conjugation (C), parity transformation (P), and time reversal (T). The CPT theorem says that CPT symmetry holds for all physical phenomena, or more precisely, that any Lorentz invariant local quantum field theory with a Hermitian Hamiltonian must have CPT symmetry.


 * Anomaly (physics) (quantum anomaly): failure of a symmetry of a theory's classical action to be a symmetry of any regularization of the full quantum theory. In classical physics, a classical anomaly is the failure of a symmetry to be restored in the limit in which the symmetry-breaking parameter goes to zero. Perhaps the first known anomaly was the dissipative anomaly in turbulence: time-reversibility remains broken (and energy dissipation rate finite) at the limit of vanishing viscosity. In quantum theory, the first anomaly discovered was the Adler–Bell–Jackiw anomaly, wherein the axial vector current is conserved as a classical symmetry of electrodynamics, but is broken by the quantized theory. Global anomalies: Scaling and renormalization; Rigid symmetries; Large gauge transformations: Witten anomaly and Wang–Wen–Witten anomaly; Higher anomalies involving higher global symmetries: Pure Yang–Mills gauge theory as an example.


 * Anomalous magnetic dipole moment of a particle: contribution of effects of quantum mechanics, expressed by Feynman diagrams with loops, to the magnetic moment of that particle. (The magnetic moment, also called magnetic dipole moment, is a measure of the strength of a magnetic source.) The "Dirac" magnetic moment, corresponding to tree-level Feynman diagrams (which can be thought of as the classical result), can be calculated from the Dirac equation. It is usually expressed in terms of the g-factor; the Dirac equation predicts $$g = 2$$. For particles such as the electron, this classical result differs from the observed value by a small fraction of a percent. The difference is the anomalous magnetic moment, denoted $$a$$ and defined as

$$ a = \frac{g-2}{2} $$


 * Lamb shift: anomalous difference in energy between two electron orbitals in a hydrogen atom. The difference was not predicted by theory and it cannot be derived from the Dirac equation, which predicts identical energies. Hence the Lamb shift refers to a deviation from theory seen in the differing energies contained by the 2S1/2 and 2P1/2 orbitals of the hydrogen atom. The Lamb shift is caused by interactions between the virtual photons created through vacuum energy fluctuations and the electron as it moves around the hydrogen nucleus in each of these two orbitals. The Lamb shift has since played a significant role through vacuum energy fluctuations in theoretical prediction of Hawking radiation from black holes. This effect was first measured in 1947 in the Lamb–Retherford experiment on the hydrogen microwave spectrum and this measurement provided the stimulus for renormalization theory to handle the divergences.

a

 * Category:Quantum field theory
 * Category:Quantum gravity


 * AdS/CFT correspondence (anti-de Sitter/conformal field theory correspondence): conjectured relationship between two kinds of physical theories. On one side are anti-de Sitter spaces (AdS) which are used in theories of quantum gravity, formulated in terms of string theory or M-theory. On the other side of the correspondence are conformal field theories (CFT) which are quantum field theories, including theories similar to the Yang–Mills theories that describe elementary particles. The duality represents a major advance in the understanding of string theory and quantum gravity. This is because it provides a non-perturbative formulation of string theory with certain boundary conditions and because it is the most successful realization of the holographic principle, an idea in quantum gravity originally proposed by Gerard 't Hooft and promoted by Leonard Susskind. The AdS/CFT correspondence was first proposed by Juan Maldacena in late 1997. Important aspects of the correspondence were soon elaborated on in two articles, one by Steven Gubser, Igor Klebanov and Alexander Polyakov, and another by Edward Witten . By 2015, Maldacena's article had over 10,000 citations, becoming the most highly cited article in the field of high energy physics, reaching over 20,000 citations in 2020.
 * Background: Quantum gravity and strings; Quantum field theory.
 * Overview of the correspondence: The geometry of anti-de Sitter space; The idea of AdS/CFT.
 * Applications to quantum gravity: A non-perturbative formulation of string theory; Black hole information paradox.
 * Applications to quantum field theory: Nuclear physics (AdS/QCD); Condensed matter physics (AdS/CMT).
 * History and development: String theory and nuclear physics; Black holes and holography; Maldacena's paper.
 * Generalizations: Three-dimensional gravity; dS/CFT correspondence; Kerr/CFT correspondence; Higher spin gauge theories.

Mechanics

 * Category:Statistical mechanics
 * Category:Particle statistics
 * Category:Fermi–Dirac statistics


 * Coriolis force: inertial or fictitious force that acts on objects that are in motion within a frame of reference that rotates with respect to an inertial frame. In a reference frame with clockwise rotation, the force acts to the left of the motion of the object. In one with anticlockwise (or counterclockwise) rotation, the force acts to the right. Deflection of an object due to the Coriolis force is called the Coriolis effect. Newton's laws of motion describe the motion of an object in an inertial (non-accelerating) frame of reference. When Newton's laws are transformed to a rotating frame of reference, the Coriolis and centrifugal accelerations appear. When applied to massive objects, the respective forces are proportional to the masses of them. The Coriolis force is proportional to the rotation rate and the centrifugal force is proportional to the square of the rotation rate. The Coriolis force acts in a direction perpendicular to the rotation axis and to the velocity of the body in the rotating frame and is proportional to the object's speed in the rotating frame (more precisely, to the component of its velocity that is perpendicular to the axis of rotation). The centrifugal force acts outwards in the radial direction and is proportional to the distance of the body from the axis of the rotating frame. These additional forces are termed inertial forces, fictitious forces or pseudo forces.


 * Fermi–Dirac statistics: type of quantum statistics that applies to the physics of a system consisting of many non-interacting, identical particles that obey the Pauli exclusion principle. A result is the Fermi–Dirac distribution of particles over energy states. It is named after Enrico Fermi and Paul Dirac, each of whom derived the distribution independently in 1926 (although Fermi derived it before Dirac). Fermi–Dirac statistics is a part of the field of statistical mechanics and uses the principles of quantum mechanics.

Fluid mechanics

 * Category:Fluid mechanics


 * Tea leaf paradox: phenomenon where tea leaves in a cup of tea migrate to the center and bottom of the cup after being stirred rather than being forced to the edges of the cup, as would be expected in a spiral centrifuge. The correct physical explanation of the paradox was for the first time given by James Thomson in 1857. He correctly connected the appearance of secondary flow (both Earth atmosphere and tea cup) with ″friction on the bottom″. The formation of secondary flows in an annular channel was theoretically treated by Boussinesq as early as in 1868. The migration of near-bottom particles in river-bend flows was experimentally investigated by A. Ya. Milovich in 1913. The solution first came from Albert Einstein in a 1926 paper in which he explained the erosion of river banks, and repudiated Baer's law.


 * Rayleigh number: dimensionless number associated with buoyancy driven flow (also known as free convection or natural convection)
 * Reynolds number: dimensionless number that gives a measure of the ratio of inertial forces to viscous forces
 * Weber number: dimensionless number in fluid mechanics that is often useful in analysing fluid flows where there is an interface between two different fluids, especially for multiphase flows with strongly curved surfaces. It can be thought of as a measure of the relative importance of the fluid's inertia compared to its surface tension. The quantity is useful in analyzing thin film flows and the formation of droplets and bubbles.


 * Lattice Boltzmann methods (LBM): originated from the lattice gas automata (LGA) method (Hardy-Pomeau-Pazzis and Frisch-Hasslacher-Pomeau models), is a class of computational fluid dynamics (CFD) methods for fluid simulation. Instead of solving the Navier–Stokes equations directly, a fluid density on a lattice is simulated with streaming and collision (relaxation) processes . The method is versatile as the model fluid can straightforwardly be made to mimic common fluid behaviour like vapour/liquid coexistence, and so fluid systems such as liquid droplets can be simulated. Also, fluids in complex environments such as porous media can be straightforwardly simulated, whereas with complex boundaries other CFD methods can be hard to work with.
 * Marangoni effect: Gibbs–Marangoni effect) is the mass transfer along an interface between two fluids due to a gradient of the surface tension. In the case of temperature dependence, this phenomenon may be called thermo-capillary convection (or Bénard–Marangoni convection).
 * Tears of wine (wine legs, fingers, curtains, church windows): manifested as a ring of clear liquid, near the top of a glass of wine, from which droplets continuously form and drop back into the wine. It is most readily observed in a wine which has a high alcohol content.

Nuclear physics

 * Category:Nuclear physics


 * Magic number (physics): number of nucleons (either protons or neutrons, separately) such that they are arranged into complete shells within the atomic nucleus. As a result, atomic nuclei with a 'magic' number of protons or neutrons are much more stable than other nuclei. The seven most widely recognized magic numbers as of 2019 are: 2, 8, 20, 28, 50, 82, 126. For protons, this corresponds to the elements He, O, Ca, Ni, Sn (tin), Pb and the hypothetical unbihexium, although 126 is so far only known to be a magic number for neutrons. Atomic nuclei consisting of such a magic number of nucleons have a higher average binding energy per nucleon than one would expect based upon predictions such as the semi-empirical mass formula and are hence more stable against nuclear decay.
 * Transuranium element: chemical elements with atomic numbers greater than 92 (the atomic number of uranium). All of these elements are unstable and decay radioactively into other elements.
 * Island of stability: predicted set of isotopes of superheavy elements that may have considerably longer half-lives than known isotopes of these elements. It is predicted to appear as an "island" in the chart of nuclides, separated from known stable and long-lived primordial radionuclides. Its theoretical existence is attributed to stabilizing effects of predicted "magic numbers" of protons and neutrons in the superheavy mass region. Several predictions have been made regarding the exact location of the island of stability, though it is generally thought to center near copernicium and flerovium isotopes in the vicinity of the predicted closed neutron shell at N = 184. These models strongly suggest that the closed shell will confer further stability towards fission and alpha decay. While these effects are expected to be greatest near atomic number Z = 114 and N = 184, the region of increased stability is expected to encompass several neighboring elements, and there may also be additional islands of stability around heavier nuclei that are doubly magic (having magic numbers of both protons and neutrons). Estimates of the stability of the nuclides within the island are usually around a half-life of minutes or days; some estimates predict half-lives of millions of years.
 * Even and odd atomic nuclei: properties of a nucleus depend on evenness or oddness of its atomic number Z, neutron number N and, consequently, of their sum, the mass number A. Most notably, oddness of both Z and N tends to lower the nuclear binding energy, making odd nuclei, generally, less stable. Nuclear spin is integer for all even-A nuclei and non-integer (half-integer) for all odd-A nuclei.
 * Neutron–proton ratio


 * Neutronium: hypothetical substance composed purely of neutrons. The word was coined by scientist Andreas von Antropoff in 1926 (before the 1932 discovery of the neutron) for the hypothetical "element of atomic number zero" (with zero protons in its nucleus) that he placed at the head of the periodic table (denoted by dash, no element symbol). However, the meaning of the term has changed over time, and from the last half of the 20th century onward it has been also used to refer to extremely dense substances resembling the neutron-degenerate matter theorized to exist in the cores of neutron stars; hereinafter "degenerate neutronium" will refer to this. In the periodic table: Mononeutron (beta decay); Dineutron (unambiguously observed in 2012 in the decay of beryllium-16. It is not a bound particle, but had been proposed as an extremely short-lived resonance state produced by nuclear reactions involving tritium); Trineutron (not been detected); Tetraneutron (hypothetical particle consisting of four bound neutrons); Pentaneutron.


 * Binding energy curve - common isotopes.svg


 * Primordial nuclide (primordial isotope): in geochemistry and geonuclear physics - nuclides found on the Earth that have existed in their current form since before Earth was formed; residues from ancient supernova explosions which occurred before the formation of the solar system. 286 primordial nuclides. The longest-lived isotope not proven to be primordial is ¹⁴⁶Sm, which has a half-life of 1.03×10⁸ years, followed by ²⁴⁴Pu (8.08×10⁷ years) and ⁹²Nb (3.5×10⁷ years). ²⁴⁴Pu has been reported to exist in nature as a primordial nuclide, although a later study did not detect it. Taking into account that all these nuclides must exist for at least 4.6×10⁹ years, ¹⁴⁶Sm must survive 45 half-lives (and hence be reduced by 2⁴⁵≈4×10¹³), ²⁴⁴Pu must survive 57 (and be reduced by a factor of 2⁵⁷≈1×10¹⁷), and ⁹²Nb must survive 130 (and be reduced by 2¹³⁰≈1×10³⁹). Mathematically, considering the likely initial abundances of these nuclides, primordial ¹⁴⁶Sm and ²⁴⁴Pu should persist somewhere within the Earth today, even if they are not identifiable in the relatively minor portion of the Earth's crust available to human assays, while ⁹²Nb and all shorter-lived nuclides should not.
 * Nucleosynthesis:
 * Big Bang nucleosynthesis (BBN; primordial nucleosynthesis): production of nuclei other than those of H-1 (proton) during the early phases of the universe: H-2 (D), He-3, He-4, Li-6, Li-7.
 * Stellar nucleosynthesis: Proton–proton chain reaction; CNO cycle; Triple-alpha process; Alpha process


 * r-process (rapid neutron-capture process): set of nuclear reactions that is responsible for the creation of approximately half of the atomic nuclei heavier than iron, the "heavy elements", with the other half produced by the p-process and s-process. The r-process usually synthesizes the most neutron-rich stable isotopes of each heavy element. The r-process can typically synthesize the heaviest four isotopes of every heavy element, and the two heaviest isotopes, which are referred to as r-only nuclei, can be created via the r-process only. Abundance peaks for the r-process occur near mass numbers A = 82 (elements Se, Br, and Kr), A = 130 (elements Te, I, and Xe) and A = 196 (elements Os, Ir, and Pt).
 * P-process (p for proton): used in two ways in the scientific literature concerning the astrophysical origin of the elements (nucleosynthesis). Originally it referred to a proton capture process which is the source of certain, naturally occurring, neutron-deficient isotopes of the elements from selenium to mercury. These nuclides are called p-nuclei and their origin is still not completely understood. Although it was shown that the originally suggested process cannot produce the p-nuclei, later on the term p-process was sometimes used to generally refer to any nucleosynthesis process supposed to be responsible for the p-nuclei.
 * Rp-process (rapid proton capture process): consecutive proton captures onto seed nuclei to produce heavier elements. It is a nucleosynthesis process and, along with the s-process and the r-process, may be responsible for the generation of many of the heavy elements present in the universe. However, it is notably different from the other processes mentioned in that it occurs on the proton-rich side of stability as opposed to on the neutron-rich side of stability. The end point of the rp-process (the highest-mass element it can create) is not yet well established, but recent research has indicated that in neutron stars it cannot progress beyond tellurium.
 * s-process (slow neutron-capture process): series of reactions in nuclear astrophysics that occur in stars, particularly asymptotic giant branch stars. The s-process is responsible for the creation (nucleosynthesis) of approximately half the atomic nuclei heavier than iron.


 * Template:Actinides vs fission products
 * Fission product
 * Decay series
 * Uranium: Enriched uranium. Uranium enrichment methods: Zippe-type centrifuge → from USSR nuclear program and Gernot Zippe to Abdul Qadeer Khan and Pakistan, Iran, North Korea and Libya having this nuclear enrichment design as well: Science vs. politics, atoms for piece vs. atoms for war.
 * Long-lived fission product (LLFP): Short-term, Medium-lived fission products (MLFP). LLFP: 1. 99Tc, 2. 126Sn, <...>, 3. 135Cs.
 * Primordial nuclide (primordial isotopes): nuclides found on the Earth that have existed in their current form since before Earth was formed. All of the known 254 stable nuclides occur as primordial nuclides, plus another 34 nuclides that have half-lives long enough to have survived from the formation of the Earth. The shortest-lived primordial nuclides (i.e. nuclides with shortest half-lives) are:

<...>,, , , , and. Because primordial chemical elements often consist of more than one primordial isotope, there are only 84 distinct primordial chemical elements. Of these, 80 have at least one observationally stable isotope and four only have radioactive isotopes.
 * Stable nuclide: atomic species that are not radioactive - that is, they do not spontaneously undergo radioactive decay


 * Nuclear isomer: metastable state of an atomic nucleus, in which one or more nucleons (protons or neutrons) occupy higher energy levels than in the ground state of the same nucleus. "Metastable" describes nuclei whose excited states have half-lives 100 to 1000 times longer than the half-lives of the excited nuclear states that decay with a "prompt" half life (ordinarily on the order of 10⁻¹² seconds). The term "metastable" is usually restricted to isomers with half-lives of 10⁻⁹ seconds or longer. Some references recommend 5 × 10⁻⁹ seconds to distinguish the metastable half life from the normal "prompt" gamma-emission half-life. Occasionally the half-lives are far longer than this and can last minutes, hours, or years. nuclear isomer survives so long (at least 1015 years) that it has never been observed to decay spontaneously. The half-life of a nuclear isomer can even exceed that of the ground state of the same nuclide, as shown by, ,  and multiple holmium isomers. The longer lives of nuclear isomers' metastable states are often due to the larger degree of nuclear spin change which must be involved in their gamma emission to reach the ground state. This high spin change causes these decays to be forbidden transitions and delayed. Delays in emission are caused by low or high available decay energy.


 * Nuclear drip line: boundary beyond which atomic nuclei are unbound with respect to the emission of a proton or neutron. An arbitrary combination of protons and neutrons does not necessarily yield a stable nucleus. One can think of moving up or to the right across the table of nuclides by adding a proton or a neutron, respectively, to a given nucleus. However, adding nucleons one at a time to a given nucleus will eventually lead to a newly formed nucleus that immediately decays by emitting a proton (or neutron). Colloquially speaking, the nucleon has leaked or dripped out of the nucleus, hence giving rise to the term drip line. Drip lines are defined for protons and neutrons at the extreme of the proton-to-neutron ratio; at p:n ratios at or beyond the drip lines, no bound nuclei can exist. While the location of the proton drip line is well known for many elements, the location of the neutron drip line is only known for elements up to neon.


 * Energy storage:
 * Atomic battery: efficiency of 0.1–5%; high efficiency betavoltaics have 6–8%
 * Radioisotope thermoelectric generator: long term battery (10-60 years); used in spaceships (1950s - 2011)


 * Prompt critical: if for each nuclear fission event, one or more of the immediate or prompt neutrons released causes an additional fission event. This causes a rapid, exponential increase in the number of fission events. Prompt criticality is a special case of supercriticality.


 * Decay chain: series of radioactive decays of different radioactive decay products as a sequential series of transformations. It is also known as a "radioactive cascade". Most radioisotopes do not decay directly to a stable state, but rather undergo a series of decays until eventually a stable isotope is reached.



History and present

 * MIT Nuclear Research Reactor (First Criticality: 1958.07.21): serves the research purposes of MIT. It is a tank-type 6 MW reactor that is moderated and cooled by light water and uses heavy water as a reflector. It is the second largest university-based research reactor in the U.S. (after the University of Missouri Research Reactor Center). It is the fourth-oldest operating reactor in USA.


 * Sellafield: history of UK nuclear industry for the military and civil needs. Nuclear reprocessing plant. Kraftwerk mentions "Sellafield".
 * COGEMA La Hague site (FR): nearly half of the world's light water reactor spent nuclear fuel reprocessing capacity. Treats fuel from FR, DE, Belgium, Swiss, Italy, JP, NL, ES.


 * CANDU reactor (CANada Deuterium Uranium): Canadian-invented, pressurized heavy water reactor used for generating electric power.


 * Thorium fuel cycle: uses an isotope of thorium,, as the fertile material. In the reactor, is transmuted into the fissile artificial uranium isotope  which is the nuclear fuel. Unlike natural uranium, natural thorium contains only trace amounts of fissile material (such as ), which are insufficient to initiate a nuclear chain reaction. Additional fissile material or another neutron source is necessary to initiate the fuel cycle. In a thorium-fuelled reactor,  absorbs neutrons to produce . This parallels the process in uranium breeder reactors whereby fertile  absorbs neutrons to form fissile . Depending on the design of the reactor and fuel cycle, the generated  either fissions in situ or is chemically separated from the used nuclear fuel and formed into new nuclear fuel. The thorium fuel cycle has several potential advantages over a uranium fuel cycle, including thorium's greater abundance, superior physical and nuclear properties, reduced plutonium and actinide production, and better resistance to nuclear weapons proliferation when used in a traditional light water reactor though not in a molten salt reactor.
 * Advanced heavy-water reactor


 * Thorium-based nuclear power: generation is fueled primarily by the nuclear fission of the isotope U-233 produced from the fertile element thorium. A thorium fuel cycle can offer several potential advantages over a uranium fuel cycle — including the much greater abundance of thorium found on Earth, superior physical and nuclear fuel properties, and reduced nuclear waste production. After studying the feasibility of using thorium, nuclear scientists Ralph W. Moir and Edward Teller suggested that thorium nuclear research should be restarted after a three-decade shutdown and that a small prototype plant should be built. Between 1999 and 2021, the number of operational thorium reactors in the world has risen from zero, to a handful of research reactors, to commercial plans for producing full-scale thorium-based reactors for use as power plants on a national scale.
 * Liquid fluoride thorium reactor: type of molten salt reactor. LFTRs use the thorium fuel cycle with a fluoride-based, molten, liquid salt for fuel.

Nuclear power plants:
 * USA:
 * Browns Ferry Nuclear Plant (Commission date: Unit 1: 1974.08.01; Unit 2: 1975.03.01; Unit 3: 1977.03.01): located on the Tennessee River near Decatur and Athens, Alabama, on the north side (right bank) of Wheeler Lake. The site has three General Electric BWR nuclear generating units and is owned entirely by the Tennessee Valley Authority (TVA). With a generating capacity of nearly 3.8 GW, it is the second most powerful nuclear plant in USA.
 * EU:
 * Nuclear power in Finland: in 2008: 4 nuclear reactors in 2 power plants. The 5th reactor is still under construction [2013]. The Finnish public is among the most nuclear power-friendly nations in the EU: in a 2008 survey, production of electricity by means of nuclear power was supported by 61%, clearly above the EU average of 44%.
 * Olkiluoto Nuclear Power Plant: one of Finland's two nuclear power plants. The Olkiluoto plant consists of two BWRs, each with a capacity of 890 MW, and one EPR type reactor (unit 3) with a capacity of 1,600 MW. This makes unit 3 currently the most powerful nuclear power plant unit in Europe and the third most powerful globally. Construction of unit 3 began in 2005. Commercial operation began in 2023.05.01, after being originally scheduled for 2009.05. Cost: The main contractor, Areva, is building the unit for a fixed price of €3 billion, so in principle, any construction costs above that price fall on Areva. In October 2013, TVO's demand for compensation from Areva had risen to €1.8 billion, and Areva's from TVO to €2.6 billion. In December 2013, Areva increased its demand to €2.7 billion. On 10 March 2018 French newspaper Le Monde announced that Areva and TVO had reached an agreement. A day later, TVO confirmed that Areva would pay it €450 million in compensation over the delays and lost income. The agreement would settle all legal actions between the two companies. With the settlement, TVO disclosed its total investment to be around €5.5 billion. Areva had accumulated losses of €5.5 billion. The total cost of the project, therefore, is estimated to be €11 billion.

History of nuclear weapons

 * Weapons-grade nuclear material: any fissionable nuclear material that is pure enough to make a nuclear weapon or has properties that make it particularly suitable for nuclear weapons use. Pu and U in grades normally used in nuclear weapons are the most common examples. (These nuclear materials have other categorizations (SNM) based on their purity.) The concentration of fissile isotopes U-235 and Pu-239 in the element used must be sufficiently high. U from natural sources is enriched by isotope separation, and Pu is produced in a suitable nuclear reactor. Experiments have been conducted with U-233 (the fissile material at the heart of the thorium fuel cycle). Neptunium-237 and some isotopes of americium might be usable, but it is not clear that this has ever been implemented.
 * Special nuclear material (SNM): term used by the Nuclear Regulatory Commission of USA to classify fissile materials. The NRC divides special nuclear material into three main categories, according to the risk and potential for its direct use in a clandestine nuclear weapon or for its use in the production of nuclear material for use in a nuclear weapon.
 * Category I: ≥5 kg U-235 (contained in U enriched to 20% or more in the U-235 isotope); ≥2 kg Pu-239; ≥2 kg U-233; ≥5 kg in any combination computed by the equation grams = (grams contained U-235) + 2.5 (grams U-233 + grams Pu-239)
 * Category II: Less than a formula quantity of strategic special nuclear material but >1,000 grams of U-235 (contained in U enriched to 20 percent or more in the U-235 isotope) or >500 grams of U-233 or Pu-239, or in a combined quantity of more than 1,000 grams (2.2 pounds) when computed by the equation grams; ≥10,000 g U-235 (contained in U enriched to ≥10% but <20% in the U-235 isotope).
 * Category III: special nuclear material of low strategic significance
 * U-235: different rules because it often is not in a pure form . Pu-239 is made in nuclear reactors by irradiating U-238 with neutrons, and U-233 is made the same way using Th-232. Since they are different elements than the source material, they can be separated relatively easily through chemical differences. However, U-235 is produced from U ore, which contains 0.7% U-235 with most of the rest consisting of U-238. Since they are the same element, they behave in similar ways and must be separated by their slightly different atomic masses. This is far more difficult than chemical separation, so varying levels of U-238 may remain after the first enrichment. If U is highly enriched, it can be used to make a nuclear weapon.

Hiroshima and Nagasaki


 * Nuclear weapons testing
 * Semipalatinsk Test Site: was the primary testing venue for USSR's nuclear weapons. It is located on the steppe in northeast Kazakhstan (then the Kazakh SSR), south of the valley of the Irtysh River. The Soviet Union conducted 456 nuclear tests at Semipalatinsk from 1949 until 1989 with little regard for their effect on the local people or environment. The full impact of radiation exposure was hidden for many years by Soviet authorities and has only come to light since the test site closed in 1991.

Nuclear power in space

 * Category:Nuclear power in space


 * List of nuclear power systems in space: 80 nuclear power systems that were flown to space, or at least launched in an attempt to reach space. Such used nuclear power systems include: radioisotope heater units (RHU); radioisotope thermoelectric generators (RTG); miniaturized fission reactors.


 * TOPAZ nuclear reactor: lightweight nuclear reactor developed for long term space use by USSR. Cooled by liquid metal, it uses a high-temperature moderator containing hydrogen and highly enriched fuel and produces electricity using a thermionic converter.
 * BES-5: Soviet thermoelectric generator that was used to power 31 satellites in the US-A (RORSAT) project. The heat source was a U-235 fast fission nuclear reactor (FNR). The BES-5 reactor was used in more than 31 satellite missions to power the radar units of the US-A surveillance satellites. The reactor was designed to be boosted to a high orbit at the end of its operational life, to prevent the radioactive fuel from re-entering earth's atmosphere.


 * Systems for Nuclear Auxiliary Power (SNAP): program of experimental radioisotope thermoelectric generators (RTGs) and space nuclear reactors flown during the 1960s by NASA.
 * Odd-numbered SNAPs: radioisotope thermoelectric generators: SNAP-3 was the first RTG used in a space mission (1961). Launched aboard U.S. Navy Transit 4A and 4B navigation satellites. The electrical output of this RTG was 2.5 W.
 * Even-numbered SNAPs: compact nuclear reactors
 * SNAP-10A: USA experimental nuclear powered satellite launched into space in 1965 as part of the SNAPSHOT program. The test marked both the world's first operation of a nuclear reactor in orbit, and the first operation of an ion thruster system in orbit. It is the only fission reactor power system launched into space by USA. The reactor stopped working after just 43 days due to a non-nuclear electrical component failure.


 * GPHS-RTG (general-purpose heat source — radioisotope thermoelectric generator): specific design of the radioisotope thermoelectric generator (RTG) used on USA space missions. The GPHS-RTG was used on Ulysses (1), Galileo (2), Cassini-Huygens (3), and New Horizons (1).
 * Multi-mission radioisotope thermoelectric generator (MMRTG): type of RTG developed for NASA space missions such as the Mars Science Laboratory (MSL), under the jurisdiction of USA DoE's Office of Space and Defense Power Systems within the Office of Nuclear Energy. The MMRTG was developed by an industry team of Aerojet Rocketdyne and Teledyne Energy Systems.

Optics

 * Category:Optics
 * Category:Nonlinear optics
 * Category:Optical quantities
 * Category:Physical optics
 * Category:Diffraction


 * Transmission coefficient: used in physics and electrical engineering when wave propagation in a medium containing discontinuities is considered. A transmission coefficient describes the amplitude, intensity, or total power of a transmitted wave relative to an incident wave. Different fields have different definitions for the term.
 * Reflectivity: the fraction of incident radiation reflected by a surface. Must be treated as a directional property that is a function of the reflected direction, the incident direction, and the incident wavelength. Commonly averaged over the reflected hemisphere to give the hemispherical spectral reflectivity
 * Speed of light: always c=299,792,458 m/s, but due to the interaction of the light and the medium (matter), the apparent average speed of light in the medium (matter) is smaller than the speed of light, because some time is needed between the excitation of the electron by the photon and the emission of the photon from the excited electron.
 * Template:Velocities of Waves:
 * Front velocity: wave discontinuity, called the front, propagates at a speed less than or equal to the speed of light c in any medium
 * Group velocity: velocity with which the overall shape of the wave's amplitudes — known as the modulation or envelope of the wave — propagates through space
 * Phase velocity: rate at which the phase of the wave propagates in space. This is the speed at which the phase of any one frequency component of the wave travels. Can be greater than the speed of light c


 * Numerical aperture (NA) of an optical system: dimensionless number that characterizes the range of angles over which the system can accept or emit light. By incorporating index of refraction in its definition, NA has the property that it is constant for a beam as it goes from one material to another, provided there is no refractive power at the interface. $$\mathrm{NA} = n \sin \theta$$


 * Newton's rings: phenomenon in which an interference pattern is created by the reflection of light between two surfaces—a spherical surface and an adjacent touching flat surface. It is named for Isaac Newton, who first studied the effect in 1717. When viewed with monochromatic light, Newton's rings appear as a series of concentric, alternating bright and dark rings centered at the point of contact between the two surfaces. When viewed with white light, it forms a concentric ring pattern of rainbow colors, because the different wavelengths of light interfere at different thicknesses of the air layer between the surfaces.


 * Kerr effect (quadratic electro-optic (QEO) effect): change in the refractive index of a material in response to an applied electric field. Induced index change is directly proportional to the square of the electric field. All materials show a Kerr effect, but certain liquids display it more strongly than others.
 * Faraday effect: magneto-optical phenomenon, an interaction between light and a magnetic field in a medium. The Faraday effect causes a rotation of the plane of polarization which is linearly proportional to the component of the magnetic field in the direction of propagation. Discovered by Michael Faraday in 1845, the Faraday effect was the first experimental evidence that light and electromagnetism are related.

Kramers–Kronig relation, Dispersion relation, Reciprocal lattice, Cardinal point (optics), Ray transfer matrix analysis


 * Diffraction-limited system: in optics, any optical instrument or system – a microscope, telescope, or camera  – has a principal limit to its resolution due to the physics of diffraction. An optical instrument is said to be diffraction-limited if it has reached this limit of resolution performance. Other factors may affect an optical system's performance, such as lens imperfections or aberrations, but these are caused by errors in the manufacture or calculation of a lens, whereas the diffraction limit is the maximum resolution possible for a theoretically perfect, or ideal, optical system.


 * F-number (f/; focal ratio, f-ratio): measure of the light-gathering ability of an optical system such as a camera lens. It is calculated by dividing the system's focal length by the diameter of the entrance pupil ("clear aperture"). It is key in determining the depth of field, diffraction, and exposure of a photograph. The f-number is dimensionless and is usually expressed using a lower-case hooked f with the format f/N, where N is the f-number.

Quantum Wave optics (diffraction) vs. particle scattering

 * Fraunhofer distance
 * Dynamical theory of diffraction: lots of red links and lots of citation from X-ray field
 * Eikonal equation: provides a link between physical (wave) optics and geometric (ray) optics
 * Optical aberration

Microscopes

 * Category:Electron microscopy
 * Category:Electron microscopy techniques
 * Category:Electron microscopy stains


 * Microscope: instrument used to see objects that are too small for the naked eye. Light, electron microscopes; scanning probe microscopes.

Photon, electron, atoms/ions: gallium, helium; mixed:
 * Scanning helium microscope
 * Transmission electron microscopy: Three-dimensional imaging: "tilt series", tomography
 * High-resolution transmission electron microscopy (HRTEM)
 * Transmission Electron Aberration-Corrected Microscope (TEAM): a project between FEI and CEOS with the support of United States Department of Energy (DOE) and 4 US laboratories.
 * Transmission Electron Aberration-corrected Microscope
 * Scanning transmission electron microscopy
 * Energy filtered transmission electron microscopy (EFTEM)
 * Cryo-electron microscopy (cryo-EM; electron cryomicroscopy)
 * Single particle analysis
 * Electron crystallography
 * Low Voltage Electron Microscopy
 * Scanning electron microscope
 * Electron diffraction
 * Electron beam induced deposition
 * X-ray microscope: see also Synchrotron X-ray tomographic microscopy (CT)


 * Detectors for transmission electron microscopy: variety of technologies available for detecting and recording the images, diffraction patterns, and electron energy loss spectra produced using TEM. CCD cameras. CMOS cameras. Direct electron detectors. Detectors for Scanning TEM (STEM).


 * Staining: auxiliary technique used in microscopy to enhance contrast in the microscopic image. Stains and dyes are frequently used in biology and medicine to highlight structures in biological tissues for viewing, often with the aid of different microscopes. In vivo vs In vitro staining. Common biological stains: Acridine orange, Bismarck brown, Carmine, Coomassie blue, Cresyl violet, Crystal violet, DAPI, Eosin, Ethidium bromide, Acid fuchsine, Haematoxylin, Hoechst stains, Iodine, Malachite green, Methyl green, Methylene blue, Neutral red, Nile blue, Nile red, Rhodamine, Safranin.
 * Negative stain: contrasting a thin specimen with an optically opaque fluid; background is stained, leaving the actual specimen untouched, and thus visible. TEM: opaqueness to electrons is related to the atomic number; stains: ammonium molybdate, uranyl acetate, uranyl formate, phosphotungstic acid, osmium tetroxide, osmium ferricyanide and auroglucothionate.
 * Uranyl formate: UO2(CHO2)2·H2O salt that exists as a fine yellow free-flowing powder occasionally used in TEM.
 * Uranyl acetate: UO2(CH3CO2)2(H2O)&middot;H2O
 * Uranyl nitrate: water-soluble yellow uranium salt with the formula UO2(NO3)2 * n H2O. The hexa-, tri-, and dihydrates are known. The compound is mainly of interest because it is an intermediate in the preparation of nuclear fuels. Stain for microscopy: Along with uranyl acetate it is used as a negative stain for viruses in electron microscopy; in tissue samples it stabilizes nucleic acids and cell membranes.

Hardware
{q.v. }
 * User:Kazkaskazkasako/Books/EECS


 * Camera (the "eye:retina"): Active pixel sensor vs. Charge-coupled device

Transfer functions and other blurs; their modeling

 * MTF: Modulation transfer function (infrared imaging), Optical transfer function
 * CTF: Contrast transfer function

Particle physics

 * Category:Particle physics
 * Category:Quantum field theory
 * Category:Standard Model


 * Template:Particles: the current model


 * Fermion (a name coined by Paul Dirac from the surname of Enrico Fermi): any particle characterized by Fermi–Dirac statistics and obeying the Pauli exclusion principle. Fermions include all quarks and leptons, as well as any composite particle made of an odd number of these, such as all baryons and many atoms and nuclei.
 * Boson (coined by Paul Dirac to commemorate the contribution of the Indian physicist Satyendra Nath Bose): Examples of bosons include fundamental particles such as photons, gluons, and W and Z bosons (the four force-carrying gauge bosons of the Standard Model), the Higgs boson, and the still-theoretical graviton of quantum gravity; composite particles (e.g. mesons and stable nuclei of even mass number such as deuterium (2H, with one proton and one neutron, mass number = 2), 4He, or 208Pb); and some quasiparticles (e.g. Cooper pairs, plasmons, and phonons).
 * Baryon: type of composite subatomic particle which contains an odd number of valence quarks (at least 3). Baryons belong to the hadron family of particles; hadrons are composed of quarks. Baryons are also classified as fermions because they have half-integer spin. The name "baryon", introduced by Abraham Pais, comes from the Greek word for "heavy" (βαρύς, barýs), because, at the time of their naming, most known elementary particles had lower masses than the baryons. Each baryon has a corresponding antiparticle (antibaryon) where their corresponding antiquarks replace quarks. For example, a proton is made of two up quarks and one down quark; and its corresponding antiparticle, the antiproton, is made of two up antiquarks and one down antiquark. Because they are composed of quarks, baryons participate in the strong interaction, which is mediated by particles known as gluons. The most familiar baryons are protons and neutrons, both of which contain three quarks, and for this reason they are sometimes called triquarks. These particles make up most of the mass of the visible matter in the universe and compose the nucleus of every atom.


 * Generation (particle physics): division of the elementary particles. Between generations, particles differ by their (flavour) quantum number and mass, but their interactions are identical. According to the results of the statistical analysis by researchers from CERN, and Humboldt University of Berlin, the existence of further fermions can be excluded with a probability of 99.99999% (5.3 sigma).


 * Barn (unit) (b): metric unit]of area equal to $m2$ (100 fm²). Originally used in nuclear physics for expressing the cross sectional area of nuclei and nuclear reactions, today it is also used in all fields of high-energy physics to express the cross sections of any scattering process, and is best understood as a measure of the probability of interaction between small particles. A barn is approximately the cross-sectional area of a uranium nucleus. The barn is also the unit of area used in nuclear quadrupole resonance and NMR to quantify the interaction of a nucleus with an electric field gradient.


 * Koide formula: $$Q = \frac{m_e + m_{\mu} + m_{\tau}}{(\sqrt{m_e}+\sqrt{m_{\mu}}+\sqrt{m_{\tau}})^2} = 0.666659|(10) \approx \frac{2}{3}.$$ Unexplained empirical equation discovered by Yoshio Koide in 1981. Running of particle masses: in quantum field theory, quantities like coupling constant and mass "run" with the energy scale - their value depends on the energy scale at which the observation occurs, in a way described by a renormalization group equation (RGE); it is expected that relationships between such quantities to be simple at high energies (where some symmetry is unbroken) but not at low energies, where the RG flow will have produced complicated deviations from the high energy relation.


 * Quark weak interactions.svg
 * Top quark (t; truth quark): most massive of all observed elementary particles (173.34 ± 0.27 (stat) ± 0.71 (syst)$GeV/c2$). Top quark interacts primarily by the strong interaction but can only decay through the weak force. Decays almost exclusively to a W boson and a bottom quark, but it can decay also into a strange quark, and on the rarest of occasions, into a down quark. All other quarks (except t) hadronize, meaning they combine with other quarks to form hadrons, and can only be observed as such.
 * Higgs boson (Higgs particle): elementary particle in the Standard Model of Particle physics. Main relevance is that it is the smallest possible excitation of the Higgs field – a field that unlike the more familiar electromagnetic field cannot be "turned off", but instead takes a constant value almost everywhere. The presence of this field explains why some fundamental particles have mass while the symmetries controlling their interactions should require them to be massless, and why the weak force has a much shorter range than the electromagnetic force.
 * W and Z bosons: W and Z bosons decay to fermion–antifermion pairs but neither the W nor the Z bosons can decay into the higher-mass top quark.


 * [[File:Standard Model of Elementary Particles.svg|thumb|600px|right|Standard model of elementary particles: the 12 fundamental fermions and 4 fundamental bosons. Brown loops indicate which bosons (red) couple to which fermions (purple and green) [2008].]]
 * Standard Model: The local SU(3)×SU(2)×U(1) gauge symmetry is an internal symmetry that essentially defines the Standard Model; discoveries of the top quark (1995), the tau neutrino (2000), and the Higgs boson (2012) have given further credence to the Standard Model.
 * Physics beyond the Standard Model

Particle physics experiments, laboratories

 * Template:CERN (European Organization for Nuclear Research):
 * Large Electron–Positron Collider (LEP): was one of the largest particle accelerators ever constructed; used from 1989 until 2000; to date, LEP is the most powerful accelerator of leptons ever built (to be replaced by ILC [13/05/23]).
 * International Linear Collider (ILC): proposed linear particle accelerator. Planned to have a collision energy of 500 GeV initially; one of the roles of the ILC would be making precision measurements of the properties of particles discovered at the LHC. The host to be chosen between: Japan, Europe (CERN) and the USA (Fermilab). Japan - the most likely candidate; construction could begin in 2015 or 2016 and will not be completed before 2026.


 * Facility for Rare Isotope Beams (FRIB): DOE Office of Science (DOE-SC) national user facility supporting the mission of the Office of Nuclear Physics; will produce large quantities of a wide variety of rare isotopes by breaking stable nuclei into rare isotopes. Funded by DOE-SC, Michigan State University, and the State of Michigan, and is being designed and established by MSU, with construction expected to begin on campus in 2013.


 * Joint Dark Energy Mission (JDEM): was an Einstein probe that planned to focus on investigating dark energy. Superseded by WFIRST.
 * Wide Field Infrared Survey Telescope (WFIRST): proposed infrared space observatory which was selected by National Research Council committee as the top priority for the next decade of astronomy. WFIRST adds some extra capabilities to the original JDEM proposal, including a search for extra-solar planets using gravitational microlensing; attempt to detect the nature of dark energy.


 * Template:Fusion experiments


 * Deep Underground Science and Engineering Laboratory (DUSEL): series of large laboratories, caverns, and cleanrooms serving the field of underground science; main impetus for DUSEL is the study of extremely rare nuclear physics processes, like neutrino scattering, dark matter interactions, and neutrinoless double beta decay, which can only be studied in the absence of cosmic rays. Double Beta Decay Underground Detector.
 * Neutrino oscillation: quantum mechanical phenomenon whereby a neutrino created with a specific lepton flavour (, μ, τ) can later be measured to have a different flavour. The probability of measuring a particular flavour for a neutrino varies periodically as it propagates through space.
 * KATRIN (Karlsruhe Tritium Neutrino Experiment) for an undertaking to measure the mass of the electron antineutrino with sub-eV precision by examining the spectrum of electrons emitted from the beta decay of tritium. The experiment is a recognized CERN experiment (RE14). The core of the apparatus is a 200-ton spectrometer.


 * Template:DOE agencies (Agencies under the United States Department of Energy)
 * United States Department of Energy national laboratories: 16 of the 17 DOE national laboratories are federally funded research and development centers administered, managed, operated and staffed by private sector organizations under a Management and Operating (M&O) contract to DOE; system of centralized national laboratories grew out of the massive scientific endeavors of WWII. Though the United States government had begun seriously investing in scientific research for national security since WWI, it was only in late 1930s and 1940s that monumental amounts of resources were committed or coordinated to wartime scientific problems, under the auspices first of the National Defense Research Committee, and later the Office of Scientific Research and Development, organized and administered by the MIT engineer Vannevar Bush. The 17 labs are:
 * Brookhaven National Laboratory (BNL; 1947): USA national laboratory
 * Relativistic Heavy Ion Collider (RHIC): the only spin-polarized proton collider ever built
 * National Synchrotron Light Source (NSLS; VUV ring: 1982- ; X-ray ring: 1984-): second generation synchrotron
 * National Synchrotron Light Source II (NSLS-II): 1000× brighter than NSLS
 * Advanced Light Source (ALS): one of the world's brightest sources of UV and soft X-ray light, the first "third-generation" synchrotron light source in its energy range, providing multiple extremely bright sources of intense and coherent short-wavelength light.
 * Argonne National Laboratory (outside Chicago): the 1st national laboratory
 * Advanced Photon Source: national synchrotron-radiation light source research facility; high-brilliance X-ray beams.
 * Oak Ridge National Laboratory (ORNL):
 * Spallation Neutron Source (SNS): accelerator-based neutron source facility that provides the most intense pulsed neutron beams in the world for scientific research and industrial development.
 * High Flux Isotope Reactor (HFIR): nuclear research reactor; operating at 85 MW, one of the highest flux reactor-based sources of neutrons for condensed matter research in USA; provides one of the highest steady-state neutron fluxes of any research reactor in the world; thermal and cold neutrons are produced by HFIR.
 * Center for Nanophase Materials Sciences (CNMS): synthesis, characterization, theory/modeling/simulation, and design of nanoscale materials.
 * SLAC National Accelerator Laboratory (originally: Stanford Linear Accelerator Center): DOE National Laboratory operated by Stanford University under the programmatic direction of the DOE-SC. RF linear accelerator; Stanford Linear Collider; SLAC Large Detector; PEP-II; Stanford Synchrotron Radiation Lightsource (SSRL); Fermi Gamma-ray Space Telescope; Kavli Institute for Particle Astrophysics and Cosmology; Linac Coherent Light Source (LCLS) - free electron laser facility.
 * Los Alamos National Laboratory (LANL; previously: Project Y, Los Alamos Laboratory, and Los Alamos Scientific Laboratory): one of two laboratories in the United States where classified work towards the design of nuclear weapons is undertaken
 * Los Alamos National Security, LLC (LANS LLC): formed by the University of California, Bechtel, Babcock & Wilcox Technical Services, and URS Energy and Construction.
 * Thomas Jefferson National Accelerator Facility (TJNAF; Jefferson Lab or JLab; until 1996: Continuous Electron Beam Accelerator Facility (CEBAF) {still commonly used for the main accelerator}): CEBAF accelerator, which consists of a polarized electron source and injector and a pair of superconducting RF linear accelerators 7/8 mile (1400 m) in length, connected to each other by two arc sections which contain steering magnets. Superconducting RF (SRF) technology uses liquid He to cool niobium to approximately 4 K, removing electrical resistance and allowing the most efficient transfer of energy to an electron. JLab houses the world's largest liquid helium refrigerator [13/05/23], and was one of the first large-scale implementators of SRF technology. Each hall (A, B, C) contains a unique spectrometer to record the results of collision between the electron beam and a stationary target. 12 GeV upgrade (double the energy): hall D. JLab houses the world's most powerful tunable free electron laser, with an output of over 14 kW [13/05/23]. CEBAF Online Data Acquisition system (CODA).
 * Sandia National Laboratories (SNL): managed and operated by the National Technology and Engineering Solutions of Sandia (a wholly owned subsidiary of Honeywell International), is one of three National Nuclear Security Administration research and development laboratories. In December 2016, it was announced that National Technology and Engineering Solutions of Sandia, under the direction of Honeywell International, will take over the management of Sandia National Laboratories starting 2017.05.01. Their primary mission is to develop, engineer, and test the non-nuclear components of nuclear weapons. The primary campus is located on Kirtland Air Force Base in Albuquerque, New Mexico and the other is in Livermore, California, next to Lawrence Livermore National Laboratory. There is also a test facility in Waimea, Kauai, Hawaii. In addition, Sandia is home to a wide variety of research including computational biology, mathematics (through its Computer Science Research Institute), materials science, alternative energy, psychology, MEMS, and cognitive science initiatives. SNL/NM is headquarters and the largest laboratory, employing more than 6,600 employees, while SNL/CA is a smaller laboratory, with about 850 employees. Tonopah and Kauai are occupied on a "campaign" basis, as test schedules dictate. Self-guided bullet
 * Z Pulsed Power Facility (Z machine): largest high frequency electromagnetic wave generator in the world and is designed to test materials in conditions of extreme temperature and pressure. Since its refurbishment in 1996.10 it has been used primarily as an inertial confinement fusion (ICF) research facility.

Atom physics

 * Category:Atomic physics


 * Heavy fermion: 4f or 5f electrons


 * Matter wave: central part of the theory of quantum mechanics, being half of wave–particle duality. All matter exhibits wave-like behavior. For example, a beam of electrons can be diffracted just like a beam of light or a water wave. The concept that matter behaves like a wave was proposed by French physicist Louis de Broglie (/dəˈbrɔɪ/) in 1924, and so matter waves are also known as de Broglie waves. $$ \lambda = \frac{h}{p}$$
 * Compton wavelength: quantum mechanical property of a particle, defined as the wavelength of a photon whose energy is the same as the rest energy of that particle (see mass–energy equivalence). $$ \lambda = \frac{h}{m c}$$

Plasma physics

 * MHD generator (magnetohydrodynamic): transforms thermal energy and kinetic energy directly into electricity.

Electricity, electrification, all energy forms are interconvertible with electrical energy (electricity)

 * Category:Electricity
 * Category:Electric power
 * Category:Electrification

{q.v. User:Kazkaskazkasako/Books/EECS}


 * Electrical energy: energy derived as a result of movement of electrons. When used loosely, electrical energy refers to energy that has been converted from electric potential energy. This energy is supplied by the combination of electric current and electric potential that is delivered by an electrical circuit (e.g., provided by an electric power utility). At the point that this electric potential energy has been converted to another type of energy, it ceases to be electric potential energy. Thus, all electrical energy is potential energy before it is delivered to the end-use.
 * Electricity meter (lt: Elektros skaitiklis; de: Stromzähler; ru: Счётчик электрической энергии)


 * Electrification: process of powering by electricity and, in many contexts, the introduction of such power by changing over from an earlier power source. The broad meaning of the term, such as in the history of technology, economic history, and economic development, usually applies to a region or national economy. Broadly speaking, electrification was the build-out of the electricity generation and electric power distribution systems that occurred in Britain, the United States, and other now-developed countries from the mid-1880s until around 1950 and is still in progress in rural areas in some developing countries. This included the transition in manufacturing from line shaft and belt drive using steam engines and water power to electric motors.


 * Corona discharge: electrical discharge brought on by the ionization of a fluid surrounding a conductor that is electrically energized; discharge will occur when the strength (potential gradient) of the electric field around the conductor is high enough to form a conductive region, but not high enough to cause electrical breakdown or arcing to nearby objects.

Superconductivity

 * Category:Superconductivity


 * Unconventional superconductor: materials that display superconductivity which does not conform to either the conventional BCS theory or the Nikolay Bogolyubov's theory or its extensions. At present it is considered unlikely that cuprate perovskite materials will achieve room-temperature superconductivity.
 * High-temperature superconductivity (high-Tc, HTS): materials that behave as superconductors at unusually high temperatures. Until 2008, only certain compounds of copper and oxygen (so-called "cuprates") were believed to have HTS properties, however, several iron-based compounds are now known to be superconducting at high temperatures. "Ordinary" or metallic superconductors usually have transition temperatures below 30 K (−243.2 °C), HTS have been observed with transition temperatures as high as 138 K (−135 °C).
 * Iron-based superconductor (ferropnictides): chemical compounds (containing iron) whosesuperconducting properties have been discovered in 2006.

Electricity generation and distribution

 * High-voltage direct current (HVDC): electric power transmission system uses direct current for the bulk transmission of electrical power. Advantages of HVDC over AC: more economic for transmitting large amounts of power point-to-point over long distances (HVDC losses are ~3.5%/1000 km), HVDC powerflow between separate AC systems can be automatically controlled to provide support for either network during transient conditions, but without the risk that a major power system collapse in one network will lead to a collapse in the second; power transmission and stabilization between unsynchronised AC networks; cable systems (underground, undersea). Disadvantages of HVDC over AC: conversion (availability of ~98.5%, converter stations are expensive), switching, control, availability, maintenance, new technology which is fast changing (spare parts are kept for the specific lines, because there is no standardization), realizing multiterminal systems is complex, HVDC circuit breakers are difficult to build (ABB made one in 2012 which switches off the current in 5 ms).
 * List of HVDC projects:
 * Tres Amigas SuperStation: focuses on uniting North America’s two major power grids (the Eastern Interconnection and the Western Interconnection) and one minor grid (the Texas Interconnection); 5 GW superconductive high-voltage direct current power transmission lines.
 * Lithuania and neighbors: NordBalt (SwedLit) - planned submarine power cable between Klaipėda (LT) and Nybro (SE); LitPol Link - planned 1000 MW electricity link between the Baltic transmission system (part of the IPS/UPS system (CIS)) and the synchronous grid of Continental Europe.

Grids:
 * Wide area synchronous grid: three-phase electric power grid that has regional scale or greater that operates at a synchronized utility frequency and is electrically tied together during normal system conditions. Also known as synchronous zones, the most powerful is the synchronous grid of Continental Europe (ENTSO-E) with 859 GW of generation, while the widest region served is that of the IPS/UPS system serving most countries of the former USSR. Synchronous grids with ample capacity facilitate electricity trading across wide areas. In the ENTSO-E in 2008, over 350,000 megawatt hours were sold per day on the European Energy Exchange (EEX). The benefits of synchronous zones include pooling of generation, resulting in lower generation costs; pooling of load, resulting in significant equalizing effects; common provisioning of reserves, resulting in cheaper primary and secondary reserve power costs; opening of the market, resulting in possibility of long term contracts and short term power exchanges; and mutual assistance in the event of disturbances. One disadvantage of a wide-area synchronous grid is that problems in one part can have repercussions across the whole grid.
 * Super grid ("mega grid"): wide area transmission network that makes it possible to trade high volumes of electricity across great distances.
 * European super grid: possible future super grid that would ultimately interconnect the various European countries and the regions around Europe's borders.
 * SuperSmart Grid (SSG): hypothetical wide area electricity network connecting Europe with northern Africa, the Middle East, Turkey and the IPS/UPS system of CIS countries.
 * Synchronous grid of Continental Europe (Continental Synchronous Area, UCTE grid): largest synchronous electrical grid (by connected power) in the world; interconnected a single phase-locked 50 Hz mains frequency electricity grid that supplies over 400 million customers in 24 countries (most of EU); 2009 - 667 GW of production capacity.
 * European Network of Transmission System Operators for Electricity (ENTSO-E; Predecessor: ETSO, UCTE, NORDEL, ATSOI, UKTSOA, BALTSO): represents 39 electricity transmission system operators (TSOs) from 35 countries across Europe, thus extending beyond EU borders. ENTSO-E was established and given legal mandates by the EU's Third Package for the Internal energy market in 2009, which aims at further liberalising the gas and electricity markets in the EU. ENTSO-E contained 42 TSOs from 35 countries as of 2021-01-08, and 39 Members from 35 countries as of 2022-01-21, as due to Brexit three Great Britain based operators left and only Northern Ireland's SONI remained from the UK. Ukrenergo and Moldelectrica were added during the 2022 Russian invasion of Ukraine on an emergency timetable.

Energy

 * Category:Energy
 * Category:Energy consumption
 * Category:Energy conversion
 * Category:Energy development
 * Category:Energy policy
 * Category:Energy sources
 * Category:Energy technology
 * Category:Gas technologies
 * Category:Energy (physics)
 * Category:Industrial gases {q.v. }

{q.v. User:Kazkaskazkasako/Books/EECS}




 * Template:Fuel cells & Fuel cell
 * By electrolyte:
 * Molten carbonate fuel cell (MCFC): high-temperature fuel cells, that operate at temperatures of 600 °C and above. Disadvantage of current MCFC technology is durability; high temperatures at which these cells operate and the corrosive electrolyte used accelerate component breakdown and corrosion, decreasing cell life.


 * Energy density: Uranium (in breeder) > Diesel / Fuel oil > Fat (animal/vegetable) > Coal > Protein


 * History of manufactured fuel gases: important for lighting, heating, and cooking purposes throughout most of the 19th century and the first half of the 20th century, began with the development of analytical and pneumatic chemistry in the 18th century. The manufacturing process for "synthetic fuel gases" (also known as "manufactured fuel gas", "manufactured gas" or simply "gas") typically consisted of the gasification of combustible materials, usually coal, but also wood and oil. The coal was gasified by heating the coal in enclosed ovens with an oxygen-poor atmosphere. The fuel gases generated were mixtures of many chemical substances, including hydrogen, methane, carbon monoxide and ethylene, and could be burnt for heating and lighting purposes. Manufactured gas utilities were founded first in England, and then in the rest of Europe and North America in the 1820s. The technology increased in scale. The ownership of the companies varied from outright municipal ownership, such as in Manchester, to completely private corporations, such as in London and most North American cities. The most important use of manufactured gas in the early 19th century was for gas lighting, as a convenient substitute for candles and oil lamps in the home. In the second half of the 19th century, the manufactured fuel gas industry diversified out of lighting and into heat and cooking. The threat from electrical light in the later 1870s and 1880s drove this trend strongly.


 * Supercapacitors chart.svg
 * Supercapacitors-vs-batteries-chart.png
 * Ragone chart: performance comparison of various energy-storing devices. On such a chart the values of energy density (in W·h/kg) are plotted versus power density (in W/kg). Both axes are logarithmic.
 * Supercapacitor (ultracapacitor): high-capacity electrochemical capacitor with capacitance values up to 10,000 farads at 1.2 volt that bridge the gap between electrolytic capacitors and rechargeable batteries. They typically store 10 to 100 times more energy per unit volume or mass than electrolytic capacitors, can accept and deliver charge much faster than batteries, and tolerate many more charge and discharge cycles than rechargeable batteries. They are however 10 times larger than conventional batteries for a given charge.
 * Electrolytic capacitor: polarized capacitors whose anode electrode (+) are made of a special metal on which an insulating oxide layer originates by anodization (forming), which acts as the dielectric of the electrolytic capacitor. A non-solid or solid electrolyte which covers the surface of the oxide layer in principle serves as the second electrode (cathode) (-) of the capacitor.

Energy (physics)

 * Category:Energy (physics)
 * Category:Dark energy


 * Dark energy: unknown form of energy that affects the universe on the largest scales. The first observational evidence for its existence came from measurements of supernovas, which showed that the universe does not expand at a constant rate; rather, the universe's expansion is accelerating. Measurements of CMB suggest the universe began in a hot Big Bang, from which general relativity explains its evolution and the subsequent large-scale motion. Without introducing a new form of energy, there was no way to explain how scientists could measure an accelerating universe. Assuming that the lambda-CDM model of cosmology is correct, as of 2013, the best current measurements indicate that dark energy contributes 68% of the total energy in the present-day observable universe. The mass–energy of dark matter and ordinary (baryonic) matter contributes 26% and 5%, respectively, and other components such as neutrinos and photons contribute a very small amount. Dark energy's density is very low (~$$7\times10^{-30}$$ g/cm3), much less than the density of ordinary matter or dark matter within galaxies. However, it dominates the universe's mass-energy content because it is uniform across space. Two proposed forms of dark energy are the cosmological constant (representing a constant energy density filling space homogeneously) and scalar fields — such as quintessence or moduli — (dynamic quantities having energy densities that vary in time and space). Contributions from scalar fields that are constant in space are usually also included in the cosmological constant. The cosmological constant can be formulated to be equivalent to the zero-point radiation of space, i.e., the vacuum energy.


 * Lambda-CDM model (ΛCDM (Lambda cold dark matter)): parameterization of the Big Bang cosmological model in which the universe contains three major components: first, a cosmological constant denoted by Lambda (Greek Λ) associated with dark energy; second, the postulated cold dark matter (abbreviated CDM); and third, ordinary matter. It is frequently referred to as the standard model of Big Bang cosmology.
 * Cold dark matter (CDM): hypothetical type of dark matter. According to the current standard model of cosmology, Lambda-CDM model, approximately 27% of the universe is dark matter and 68% is dark energy, with only a small fraction being the ordinary baryonic matter that composes stars, planets, and living organisms. Cold refers to the fact that the dark matter moves slowly compared to the speed of light, while dark indicates that it interacts very weakly with ordinary matter and electromagnetic radiation.

Energy sources, fuels

 * Category:Energy sources
 * Category:Chemical energy sources
 * Category:Fuels
 * Category:Fossil fuels
 * Category:Nuclear fuels
 * Category:Nuclear fuel infrastructure
 * Category:Wind power
 * Category:Windmills
 * Category:Energy development
 * Category:Energy economics
 * Category:Fuel production
 * Category:Uranium mining

{q.v. }
 * 
 * 
 * User:Kazkaskazkasako/Books/All
 * Fossil fuels: coal, oil, gas


 * World energy resources: fossil fuel, nuclear fuel and renewable resources.


 * Tower mill: type of vertical windmill consisting of a brick or stone tower, on which sits a wooden 'cap' or roof, which can rotate to bring the sails into the wind. This rotating cap on a firm masonry base gave tower mills great advantages over earlier post mills, as they could stand much higher, bear larger sails, and thus afford greater reach into the wind. Windmills in general had been known to civilization for centuries, but the tower mill represented an improvement on traditional western-style windmills. The tower mill was an important source of power for Europe for nearly 600 years from 1300 to 1900, contributing to 25% of the industrial power of all wind machines before the advent of the steam engine and coal power.
 * Smock mill: type of windmill that consists of a sloping, horizontally weatherboarded, thatched, or shingled tower, usually with six or eight sides. It is topped with a roof or cap that rotates to bring the sails into the wind. This type of windmill got its name from its resemblance to smocks worn by farmers in an earlier period. They reached their heyday in the earlier part of the 19th century, after which the advent of steam power started the decline of the windmill.


 * Energy development: making available sufficient primary energy sources and secondary energy forms to meet the needs of society; energy conservation and energy efficiency;
 * Economics of nuclear power plants: controversial subject, since there are diverging views on this topic, and multi-billion dollar investments ride on the choice of an energy source. Nuclear power plants typically have high capital costs for construction and for decommissioning as well as the ongoing and future costs of storing nuclear waste. Current benefits of nuclear energy include low fuel costs and low greenhouse gas emissions .
 * Nuclear power debate: long-running controversy about the risks and benefits of using nuclear reactors to generate electricity for civilian purposes. The debate about nuclear power peaked during the 1970s and 1980s, as more and more reactors were built and came online, and "reached an intensity unprecedented in the history of technology controversies" in some countries. Thereafter, the nuclear industry created jobs, focused on safety, and public concerns mostly waned. In the 2010+ decade, with growing public awareness about climate change and the critical role that carbon dioxide and methane emissions plays in causing the heating of the earth's atmosphere, there was a resurgence in the intensity of the nuclear power debate. Nuclear power advocates and those most concerned about climate change point to nuclear power's reliable, emission-free, high-density energy, alongside a generation of young physicists and engineers working to bring a new generation of nuclear technology into existence to replace fossil fuels Proponents advance the notion that nuclear power produces virtually no air pollution, in contrast to the massive amount of pollution and carbon emission generated from burning fossil fuels like coal, oil and natural gas. Modern society demands always-on energy to power communications, computer networks, transportation, industry and residences at all times of day and night. In the absence of nuclear power, utilities need to burn fossil fuels to keep the energy grid reliable, even with access to solar and wind energy, because those sources are intermittent. Proponents also believe that nuclear power is the only viable course for a country to achieve energy independence while also meeting their "ambitious" Nationally Determined Contributions (NDCs) to reduce carbon emissions in accordance with the Paris Agreement signed by 195 nations. Reliability. Economics: New nuclear plants; Cost of decommissioning nuclear plants; Subsidies: Indirect nuclear insurance subsidy. Environmental effects: EU Taxonomy; Effect on greenhouse gas emissions; High-level radioactive waste; Prevented mortality.


 * Nuclear fuel cycle (nuclear fuel chain): progression of nuclear fuel through a series of differing stages. It consists of steps in the front end, which are the preparation of the fuel, steps in the service period in which the fuel is used during reactor operation, and steps in the back end, which are necessary to safely manage, contain, and either reprocess or dispose of spent nuclear fuel. If spent fuel is not reprocessed, the fuel cycle is referred to as an open fuel cycle (or a once-through fuel cycle); if the spent fuel is reprocessed, it is referred to as a closed fuel cycle.
 * Uranium mining: process of extraction of uranium ore from the ground. Over 50 thousand tons of uranium were produced in 2019. Kazakhstan, Canada, and Australia were the top three uranium producers, respectively, and together account for 68% of world production. Other countries producing more than 1,000 tons per year included Namibia, Niger, Russia, Uzbekistan, the United States, and China. Nearly all of the world's mined uranium is used to power nuclear power plants. Historically uranium was also used in applications such as uranium glass or ferrouranium but those applications have declined due to the radioactivity of uranium and are nowadays mostly supplied with a plentiful cheap supply of depleted uranium which is also used in uranium ammunition . Uranium is mined by in-situ leaching (57% of world production) or by conventional underground or open-pit mining of ores (43% of production). During in-situ mining, a leaching solution is pumped down drill holes into the uranium ore deposit where it dissolves the ore minerals. The uranium-rich fluid is then pumped back to the surface and processed to extract the uranium compounds from solution. In conventional mining, ores are processed by grinding the ore materials to a uniform particle size and then treating the ore to extract the uranium by chemical leaching. The milling process commonly yields dry powder-form material consisting of natural uranium, "yellowcake," which is nowadays commonly sold on the uranium market as U₃O₈.


 * Merit order: way of ranking available sources of energy, especially electrical generation, based on ascending order of price (which may reflect the order of their short-run marginal costs of production) together with amount of energy that will be generated. In a centralized management, the ranking is so that those with the lowest marginal costs are the first ones to be brought online to meet demand, and the plants with the highest marginal costs are the last to be brought on line. Increasing the supply of renewable energy tends to lower the average price per unit of electricity because wind energy and solar energy have very low marginal costs: they do not have to pay for fuel, and the sole contributor to their marginal cost is operational cost. As a result, their electricity, this costs fully covered by the FIT revenue, is, on the spot market, less costly than that from coal or natural gas, and transmission companies buy from them first. Moreover, solar energy is typically most abundant in the middle of the day, coinciding closely with peak demand, so that it is in the best position to displace coal and natural gas electricity when those sources are charging the highest premium . Study by the Fraunhofer Institute found that this "merit order effect" had allowed solar power to reduce the price of electricity on the German energy exchange by 10% on average, and by as much as 40% in the early afternoon, in 2007; as more solar electricity is fed into the grid, peak prices will come down even further.


 * Shale gas by country: unconventional natural gas produced from shale, a type of sedimentary rock. Shale gas has become an increasingly important source of natural gas in USA over the past decade, and interest has spread to potential gas shales in Canada, Europe, Asia, and Australia. One analyst expects shale gas to supply as much as half the natural gas production in North America by 2020.


 * Compressed natural gas (CNG): fuel gas mainly composed of methane (CH₄), compressed to less than 1% of the volume it occupies at standard atmospheric pressure. It is stored and distributed in hard containers at a pressure of 20–25 megapascals (2,900–3,600 psi), usually in cylindrical or spherical shapes.
 * Energy density: CNG's energy density is the same as liquefied natural gas at 53.6 MJ/kg. Its volumetric energy density, 9 MJ/L, is 42 % of that of LNG (22 MJ/L) because it is not liquefied, and is 25% that of diesel fuel.
 * Liquefied natural gas (LNG): natural gas (predominantly methane, CH₄, with some mixture of ethane, C₂H₆) that has been cooled down to liquid form for ease and safety of non-pressurized storage or transport. It takes up about 1/600th the volume of natural gas in the gaseous state (at standard conditions for temperature and pressure). LNG is odorless, colorless, non-toxic and non-corrosive. Hazards include flammability after vaporization into a gaseous state, freezing and asphyxia. The liquefaction process involves removal of certain components, such as dust, acid gases, helium, water, and heavy hydrocarbons, which could cause difficulty downstream. The natural gas is then condensed into a liquid at close to atmospheric pressure by cooling it to approximately −162 °C; maximum transport pressure is set at around 25 kPa (gauge pressure), which is about one-fourth times atmospheric pressure at sea level. The "acidic" elements such as hydrogen sulphide (H₂S) and carbon dioxide (CO₂), together with oil, mud, water, and mercury, are removed from the gas to deliver a clean sweetened stream of gas. Failure to remove much or all of such acidic molecules, mercury, and other impurities could result in damage to the equipment. Corrosion of steel pipes and amalgamization of mercury to aluminum within cryogenic heat exchangers could cause expensive damage.
 * Liquefied petroleum gas (LPG): fuel gas which contains a flammable mixture of hydrocarbon gases, specifically propane, propylene, butylene, isobutane and n-butane. LPG is used as a fuel gas in heating appliances, cooking equipment, and vehicles. It is increasingly used as an aerosol propellant and a refrigerant, replacing chlorofluorocarbons in an effort to reduce damage to the ozone layer. When specifically used as a vehicle fuel, it is often referred to as autogas or even just as gas.

Sustainable energy

 * Category:Sustainable energy
 * Category:Renewable energy
 * Category:Renewable electricity
 * Category:Solar power


 * Renewable energy in the European Union
 * Renewable energy in Germany: 2012: ~25% electricity; 2014: 30%. 2011 renewable distribution: 40% wind, 30% biomass, 16% photovoltaics, 14% hydropower, (0.015% geothermal).
 * Wind power in Germany: ~10% of energy needs by 2010-2011.


 * Duck curve: graph of power production over the course of a day that shows the timing imbalance between peak demand and renewable energy production. In many energy markets the peak demand occurs after sunset, when solar power is no longer available. In locations where a substantial amount of solar electric capacity has been installed, the amount of power that must be generated from sources other than solar or wind displays a rapid increase around sunset and peaks in the mid-evening hours, producing a graph that resembles the silhouette of a duck. Without any form of energy storage, after times of high solar generation generating companies must rapidly increase power output around the time of sunset to compensate for the loss of solar generation, a major concern for grid operators where there is rapid growth of photovoltaics. Storage can fix these issues if it can be implemented. Flywheels have shown to provide excellent frequency regulation. Short term use batteries, at a large enough scale of use, can help to flatten the duck curve and prevent generator use fluctuation and can help to maintain voltage profile. However, cost is a major limiting factor for energy storage as each technique is expensive to produce at scale and comparatively not energy dense compared to liquid fossil fuels. [hydrogen?]

Solar energy

 * Category:Solar power
 * Category:Photovoltaics
 * Category:Photovoltaics manufacturers
 * Category:Solar cells
 * Category:Silicon solar cells
 * Category:Thin-film cells


 * Sunshine duration: climatological indicator, measuring duration of sunshine in given period (usually, a day or a year) for a given location on Earth, typically expressed as an averaged value over several years. It is a general indicator of cloudiness of a location, and thus differs from insolation, which measures the total energy delivered by sunlight over a given period.


 * Polycrystalline silicon (multicrystalline silicon, polysilicon): high purity, polycrystalline form of silicon, used as a raw material by the solar photovoltaic and electronics industry. Polysilicon is produced from metallurgical grade silicon by a chemical purification process, called the Siemens process. This process involves distillation of volatile silicon compounds, and their decomposition into silicon at high temperatures. An emerging, alternative process of refinement uses a fluidized bed reactor. The photovoltaic industry also produces upgraded metallurgical-grade silicon (UMG-Si), using metallurgical instead of chemical purification processes. When produced for the electronics industry, polysilicon contains impurity levels <1 ppb, while polycrystalline solar grade silicon (SoG-Si) is generally less pure.


 * Perovskite solar cell: type of solar cell that includes a perovskite-structured compound, most commonly a hybrid organic–inorganic lead or tin halide-based material as the light-harvesting active layer. Perovskite materials, such as methylammonium lead halides and all-inorganic caesium lead halide, are cheap to produce and simple to manufacture. Efficiencies of laboratory-scale devices using these materials have increased from 3.8% in 2009 to 25.7% in 2021 in single-junction architectures, and, in silicon-based tandem cells, to 29.8%, exceeding the maximum efficiency achieved in single-junction silicon solar cells. Perovskite solar cells have therefore been the fastest-advancing solar technology as of 2016.


 * Cadmium telluride photovoltaics: PV technology that is based on the use of cadmium telluride, a thin semiconductor layer designed to absorb and convert sunlight into electricity. Cadmium telluride PV is the only thin film technology with lower costs than conventional solar cells made of crystalline silicon in multi-kilowatt systems. On a lifecycle basis, CdTe PV has the smallest carbon footprint, lowest water use and shortest energy payback time of all solar technologies. CdTe's energy payback time of less than a year allows for faster carbon reductions without short-term energy deficits. Solar tracking; Cadmium - waste byproduct of zinc refining therefore its production does not depend on PV market demand; Tellurium production and reserves estimates are subject to uncertainty and vary considerably.


 * First Solar: USA photovoltaic (PV) manufacturer of rigid thin film modules, or solar panels, and a provider of utility-scale PV power plants and supporting services that include finance, construction, maintenance and end-of-life panel recycling. First Solar uses cadmium telluride (CdTe) as a semiconductor to produce CdTe-panels, that are competing successfully with conventional crystalline silicon technology.


 * Solar power in Germany: consists almost exclusively of PV and accounted for an estimated 6.2%-6.9% of the country's net-electricity generation in 2014.

Nuclear fission

 * Category:Background radiation

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 * Template:Nuclear technology: molten salt reactor, integral fast reactor
 * SCRAM: emergency shutdown of a nuclear reactor: insert neutron-absorbing control rods into the core
 * Spent fuel pool: storage pools for spent fuel from nuclear reactors
 * Traveling wave reactor
 * Terrapower: nuclear reactor design company headquartered in Bellevue, Washington, in the United States. TerraPower is a class of nuclear fast reactors called the traveling wave reactor (TWR). Unlike standard light water reactors such as PWRs or BWRs that operate by using enriched uranium as fuel, TWR uses depleted uranium instead, with an estimated operation period from 40 to 60 years. The byproduct of the U-235 fission can be re-used for other TWR reactors.
 * Micro nuclear reactor
 * Toshiba 4S: micro sodium reactor design.
 * Passive nuclear safety (1) no moving working fluid; (2) no moving mechanical part; (3) no signal inputs of 'intelligence'; (4) no external power input or forces


 * Natural nuclear fission reactor: uranium deposit where self-sustaining nuclear chain reactions have occurred. This can be examined by analysis of isotope ratios. The conditions under which a natural nuclear reactor could exist had been predicted in 1956 by Paul Kazuo Kuroda. The phenomenon was discovered in 1972 in Oklo, Gabon by French physicist Francis Perrin under conditions very similar to what was predicted. Oklo is the only known location for this in the world and consists of 16 sites with patches of centimeter-sized ore layers. Here self-sustaining nuclear fission reactions are thought to have taken place approximately 1.7 billion years ago, and ran for a few hundred thousand years, averaging probably less than 100 kW of thermal power during that time.


 * Burnup (fuel utilization): measure of how much energy is extracted from a primary nuclear fuel source. It is measured both as the fraction of fuel atoms that underwent fission in %FIMA (fissions per initial metal atom) and as the actual energy released per mass of initial fuel in gigawatt-days/metric ton of heavy metal (GWd/tHM).


 * Plutonium-239 (Pu-239, 239Pu): primary fissile isotope used for the production of nuclear weapons, although U-235 is also used for that purpose. Pu-239 is also one of the three main isotopes demonstrated usable as fuel in thermal spectrum nuclear reactors, along with U-235 and U-233. Pu-239 has a half-life of 24,110 years.


 * Pebble-bed reactor (PBR): design for a graphite-moderated, gas-cooled nuclear reactor. It is a type of very-high-temperature reactor (VHTR), one of the six classes of nuclear reactors in the Generation IV initiative. The basic design of pebble-bed reactors features spherical fuel elements called pebbles. These tennis ball-sized pebbles (approx. 6.7 cm or 2.6 in in diameter) are made of pyrolytic graphite (which acts as the moderator), and they contain thousands of micro-fuel particles called tristructural-isotropic (TRISO) particles. These TRISO fuel particles consist of a fissile material (such as U-235) surrounded by a ceramic layer coating of silicon carbide for structural integrity and fission product containment. In the PBR, thousands of pebbles are amassed to create a reactor core, and are cooled by a gas, such as helium, nitrogen or carbon dioxide, that does not react chemically with the fuel elements. Other coolants such as FLiBe (molten fluoride, lithium, beryllium salt) ) have also been suggested for implementation with pebble fuelled reactors. Some examples of this type of reactor are claimed to be passively safe.
 * Project Pele: project of the US DoD to build a deployable nuclear power reactor for use in USA Armed Forces remote operating bases. In 2020 the project was listed as relevant to lunar and Mars missions presumably for surface operations rather than rocket propulsion.
 * BWX Technologies: supplier of nuclear components and fuel to the U.S. 2015.07.01, BWX Technologies Inc. began trading separately from its former subsidiary Babcock & Wilcox Enterprises Inc. after a spinoff.
 * BWXT mPower, Inc. (2012-): develop, license, and deploy the B&W mPower reactor, a small modular nuclear reactor. The BWXT mPower reactor – no longer in development as of 2017 – was a scalable, modular reactor with the capacity to provide output in increments of 180 MWe for a four-year operating cycle without refueling. BWXT announced in 2009 plans to design, develop, license and deploy a small modular nuclear reactor (SMR) called the BWXT mPower reactor.
 * Westinghouse Electric Company: USA nuclear power company formed in 1999 from the nuclear power division of the original Westinghouse Electric Corporation. It offers nuclear products and services to utilities internationally, including nuclear fuel, service and maintenance, instrumentation, control and design of nuclear power plants. 2017.03.24, parent company Toshiba announced that Westinghouse Electric Company would file for Chapter 11 bankruptcy because of US$9 bln. of losses from nuclear reactor construction projects. In 2018, Westinghouse was acquired by Brookfield Business Partners and some partners.
 * X-energy: USA private nuclear reactor and fuel design engineering company. It is developing a Generation IV high-temperature gas-cooled pebble-bed nuclear reactor design.


 * Low-background steel (pre-war steel): any steel produced prior to the detonation of the first nuclear bombs in the 1940s and 1950s. Typically sourced from ships (either as part of regular scrapping or shipwrecks) and other steel artifacts of this era, it is often used for modern particle detectors because more modern steel is contaminated with traces of nuclear fallout.

Nuclear fusion

 * Category:Nuclear fusion
 * Category:Fusion power

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 * Nuclear fusion: reaction in which two or more atomic nuclei are combined to form one or more different atomic nuclei and subatomic particles (neutrons or protons). The difference in mass between the reactants and products is manifested as either the release or absorption of energy. This difference in mass arises due to the difference in nuclear binding energy between the atomic nuclei before and after the reaction. Nuclear fusion is the process that powers active or main sequence stars and other high-magnitude stars, where large amounts of energy are released. A nuclear fusion process that produces atomic nuclei lighter than iron-56 or nickel-62 will generally release energy. These elements have a relatively small mass and a relatively large binding energy per nucleon. Fusion of nuclei lighter than these releases energy (an exothermic process), while the fusion of heavier nuclei results in energy retained by the product nucleons, and the resulting reaction is endothermic. The opposite is true for the reverse process, called nuclear fission. Nuclear fusion uses lighter elements, such as hydrogen and helium, which are in general more fusible; while the heavier elements, such as uranium, thorium and plutonium, are more fissionable. The extreme astrophysical event of a supernova can produce enough energy to fuse nuclei into elements heavier than iron.


 * ITER (originally an acronym: International Thermonuclear Experimental Reactor): international nuclear fusion research and engineering megaproject, which is currently building the world's largest experimental tokamak nuclear fusion reactor adjacent to the Cadarache facility in the south of France. The ITER project aims to make the long-awaited transition from experimental studies of plasma physics to full-scale electricity-producing fusion power plants. The project is funded and run by seven member entities — the European Union, India, Japan, China, Russia, South Korea and the United States. The EU, as host party for the ITER complex, is contributing about 45%, with the other six parties contributing approximately 9% each.
 * DEMOnstration Power Plant: proposed class of nuclear fusion experimental reactors that are intended to demonstrate the net production of electric power from nuclear fusion. Most of the ITER partners have plans for their own DEMO-class reactors. With the possible exception of the EU and Japan, there are no plans for international collaboration as there was with ITER.


 * Stellarator: device used to confine a hot plasma with magnetic fields in order to sustain a controlled nuclear fusion reaction. Stellarators were popular in the 1950s and 60s, but the much better results from tokamak designs led to them falling from favor in the 1970s. More recently, in the 1990s, problems with the tokamak concept have led to renewed interest in the stellarator design, and a number of new devices have been built.
 * Wendelstein 7-X: experimental stellarator built in Greifswald, Germany by the Max-Planck-Institut für Plasmaphysik, and completed in October 2015.
 * Helically Symmetric Experiment: experimental plasma confinement device at the University of Wisconsin-Madison, which design principles are hoped to be incorporated into a fusion reactor.
 * Large Helical Device: fusion research device in Toki, Gifu, Japan and is the second largest superconducting stellarator in the world, employing a heliotron magnetic field originally developed in Japan.


 * History of the Teller–Ulam design: technical concept behind modern thermonuclear weapons, also known as hydrogen bombs. This design, the details of which are military secrets known to only a handful of major nations, is believed to be used in virtually all modern nuclear weapons which make up the arsenals of the major nuclear powers. Teller's "Super". The Teller–Ulam design was for many years considered one of the top nuclear secrets, and even today it is not discussed in any detail by official publications with origins "behind the fence" of classification. USA DOE policy has been, and continues to be, that they do not acknowledge when "leaks" occur, because doing such would acknowledge the accuracy of the supposed leaked information.
 * Tsar Bomba (1961.10.30; Blast yield: 50–58 megatons of TNT (210–240 PJ)): thermonuclear aerial bomb, and the most powerful nuclear weapon ever created and tested. The Soviet physicist Andrei Sakharov oversaw the project at Arzamas-16, while the main work of design was by Sakharov, Viktor Adamsky, Yuri Babayev, Yuri Smirnov, and Yuri Trutnev. The project was ordered by Nikita Khrushchev in July 1961 as part of the Soviet resumption of nuclear testing after the Test Ban Moratorium, with the detonation timed to coincide with the 22nd Congress of the Communist Party of USSR.

Liquid fuels, Petroleum products

 * Category:Liquid fuels
 * Category:Aviation fuels
 * Category:Petroleum technology
 * Category:Oil refining
 * Category:Petroleum production
 * Category:Petroleum products
 * Category:Aviation fuels


 * Octane rating (octane number): standard measure of the performance of an engine or aviation fuel. The higher the octane number, the more compression the fuel can withstand before detonating (igniting). In broad terms, fuels with a higher octane rating are used in high-performance gasoline engines that require higher compression ratios. In contrast, fuels with lower octane numbers (but higher cetane numbers) are ideal for diesel engines, because diesel engines (also referred to as compression-ignition engines) do not compress the fuel, but rather compress only air and then inject fuel into the air which was heated by compression. Gasoline engines rely on ignition of air and fuel compressed together as a mixture, which is ignited at the end of the compression stroke using spark plugs. Therefore, high compressibility of the fuel matters mainly for gasoline engines. Use of gasoline with lower octane numbers may lead to the problem of engine knocking. Research Octane Number (RON): 91, 92, 93, 95, 96, 98, 99, 100.


 * Avgas (aviation gasoline): aviation fuel used in spark-ignited internal-combustion engines to propel aircraft. Avgas is distinguished from mogas (motor gasoline), which is the everyday gasoline used in motor vehicles and some light aircraft. Unlike mogas, which has been formulated since the 1970s to allow the use of platinum-content catalytic converters for pollution reduction, the most commonly used grades of avgas still contain tetraethyllead (TEL), a toxic substance used to prevent engine knocking (detonation), with ongoing experiments aimed at eventually reducing or eliminating the use of TEL in aviation gasoline.


 * Saudi Aramco (Saudi Arabian Oil Company (formerly Arabian-American Oil Company)): Saudi Arabian national petroleum and natural gas company based in Dhahran, Saudi Arabia. 2019.12.11 the company's shares commenced trading on the Tadawul stock exchange. The shares rose to 35.2 riyals, giving it a market capitalisation of about $1.88 trillion. 2019.12, Saudi Aramco became worth $2.1 trillion dollars surpassing Apple. This made it the most 'valuable' company of the world.

Materials science, phases of matter

 * Category:Materials science
 * Category:Condensed matter physics
 * Category:Soft matter
 * Category:Solid state engineering
 * Category:Metallurgy
 * Category:Microtechnology: 10−4 to 10−7 m
 * Category:Nanotechnology
 * Category:Supramolecular chemistry
 * Category:Clathrates
 * Category:Clathrate hydrates
 * Category:Molecular machines
 * Category:Polymer chemistry
 * Category:Superconductivity {q.v. User:Kazkaskazkasako/Books/EECS}
 * Category:Phases of matter
 * Category:Bubbles (physics)
 * Category:Particle detectors
 * Category:Nanotechnology templates
 * Category:Applied and interdisciplinary physics
 * Category:Materials science

{q.v. User:Kazkaskazkasako/Books/EECS}


 * Materials science: Materials in industry (Ceramics and glasses, Composite materials, Polymers, Metal alloys)
 * Template:Nanotechnology (Template:Nanotech footer is the same) R
 * List of nanotechnology organizations: MRS (Materials Research Society)
 * Mechanosynthesis: chemical synthesis in which reaction outcomes are determined by the use of mechanical constraints to direct reactive molecules to specific molecular sites. In biology, the ribosome provides an example of a programmable mechanosynthetic device; diamond mechanosynthesis
 * Template:Molecular nanotechnology & Molecular nanotechnology (MNT): build structures to complex, atomic specifications by means of mechanosynthesis (reaction outcomes are determined by the use of mechanical constraints to direct reactive molecules to specific molecular sites). Combines physics, chemistry, life molecular machinery, and systems engineering of macroscale factories. Hard vs soft nanotech: hard would use vacuum and ~0 K to engineer stuff while the soft nanotech talks about wetness, stickness, brownian motion, high viscosity - biomimetic nanontech.
 * Molecular assembler: defined by K. Eric Drexler, is a "proposed device able to guide chemical reactions by positioning reactive molecules with atomic precision" (e.g. ribosome is a real molecular assembler in the liquids of the cell where the instruction is mRNA and the output in protein, while aa-tRNAs are used up). Nanofactories, self-replication. One molecular assembler, like a single ribosome, are slow, but when you have many of them, then you can produce in quantity (that's why cell produces ~2× ribosomes compared to the just-after-the-division point and only then divides into 2 daughter cells).
 * Drexler–Smalley debate on molecular nanotechnology: from wet/soft MNT (to bootstrap) to hard MNT? Quantum mechanics? Smalley argued that nearly all of modern chemistry involves reactions that take place in a solvent (usually water), because the small molecules of a solvent contribute many things, such as lowering binding energies for transition states. Since nearly all known chemistry requires a solvent, Smalley felt that Drexler's proposal to use a high vacuum environment was not feasible; "fat fingers problem" and the "sticky fingers problem".
 * Molecular engineering: companies:
 * Zyvex → Zyvex Technologies (Zyvex Marine): works with carbon nanotubes embedded into resins to make several times lighter than alloys but as strong as alloys materials.


 * Density of states: number of states per interval of energy at each energy level that are available to be occupied.


 * Condensed matter physics


 * Soft matter: variety of physical states that are easily deformed by thermal stresses or thermal fluctuations. They include liquids, colloids, polymers, foams, gels, granular materials, liquid crystals, and a number of biological materials.


 * Nucleation: first step in the formation of either a new thermodynamic phase or a new structure via self-assembly or self-organization. Nucleation is typically defined to be the process that determines how long an observer has to wait before the new phase or self-organized structure appears. For example, if a volume of water is cooled (at atmospheric pressure) below 0 °C, it will tend to freeze into ice, but volumes of water cooled only a few degrees below 0 °C often stay completely free of ice for long periods. At these conditions, nucleation of ice is either slow or does not occur at all. However, at lower temperatures ice crystals appear after little or no delay. At these conditions ice nucleation is fast . Nucleation is commonly how first-order phase transitions start, and then it is the start of the process of forming a new thermodynamic phase . In contrast, new phases at continuous phase transitions start to form immediately.


 * Flory–Huggins solution theory: lattice model of the thermodynamics of polymer solutions which takes account of the great dissimilarity in molecular sizes in adapting the usual expression for the entropy of mixing. The result is an equation for the Gibbs free energy change $$\Delta G_m$$ for mixing a polymer with a solvent. Although it makes simplifying assumptions, it generates useful results for interpreting experiments.


 * Spinodal decomposition: one thermodynamic phase decomposing into two phases, when there is no nucleation barrier to this decomposition. Thus at least some fluctuations in the system spontaneously grow as they reduce the free energy, and so there is no waiting, as there typically is when there is a nucleation barrier. Spinodal decomposition can occur, for example, when mixtures of polymers are unstable as a mixture and separate into two coexisting phases, each one rich in one polymer, and poor in the other. It can also occur in metal alloys.


 * Molecular self-assembly: process by which molecules adopt a defined arrangement without guidance or management from an outside source. There are two types of self-assembly. These are intramolecular self-assembly and intermolecular self-assembly. Commonly, the term molecular self-assembly refers to intermolecular self-assembly, while the intramolecular analog is more commonly called folding. Supramolecular systems. Biological systems: Protein multimers. Nanotechnology: DNA nanotechnology. Two-dimensional monolayers.


 * Friability: condition of being friable, describes the tendency of a solid substance to break into smaller pieces under duress or contact, especially by rubbing. The opposite of friable is indurate. Substances that are designated hazardous, such as asbestos or crystalline silica, are often said to be friable if small particles are easily dislodged and become airborne, and hence respirable (able to enter human lungs), thereby posing a health hazard. Tougher substances, such as concrete, may also be mechanically ground down and reduced to finely divided mineral dust. However, such substances are not generally considered friable because of the degree of difficulty involved in breaking the substance's chemical bonds through mechanical means. Some substances, such as polyurethane foams, show an increase in friability with exposure to ultraviolet radiation, as in sunlight.


 * Clathrate hydrate (gas hydrates, clathrates, hydrates): crystalline water-based solids physically resembling ice, in which small non-polar molecules (typically gases) or polar molecules with large hydrophobic moieties are trapped inside "cages" of hydrogen bonded, frozen water molecules. Most low molecular weight gases, including O₂, H₂, N₂, CO₂, CH₄, H₂S, Ar, Kr, and Xe, as well as some higher hydrocarbons and freons, will form hydrates at suitable temperatures and pressures. The formation and decomposition of clathrate hydrates are first order phase transitions, not chemical reactions. Their detailed formation and decomposition mechanisms on a molecular level are still not well understood. Hydrocarbon clathrates cause problems for the petroleum industry, because they can form inside gas pipelines, often resulting in obstructions. Deep sea deposition of carbon dioxide clathrate has been proposed as a method to remove this greenhouse gas from the atmosphere and control climate change. Clathrates are suspected to occur in large quantities on some outer planets, moons and trans-Neptunian objects, binding gas at fairly high temperatures.
 * Methane clathrate (CH₄·5.75H₂O or 8CH₄·46H₂O): solid clathrate compound (more specifically, a clathrate hydrate) in which a large amount of methane is trapped within a crystal structure of water, forming a solid similar to ice. Originally thought to occur only in the outer regions of the Solar System, where temperatures are low and water ice is common, significant deposits of methane clathrate have been found under sediments on the ocean floors of the Earth. Methane hydrate is formed when hydrogen-bonded water and methane gas come into contact at high pressures and low temperatures in oceans. In 2008, research on Antarctic Vostok Station and EPICA Dome C ice cores revealed that methane clathrates were also present in deep Antarctic ice cores and record a history of atmospheric methane concentrations, dating to 800,000 years ago. The ice-core methane clathrate record is a primary source of data for global warming research, along with oxygen and carbon dioxide. Some active seeps instead act as a minor carbon sink, because with the majority of methane dissolved underwater and encouraging methanotroph communities, the area around the seep also becomes more suitable for phytoplankton. As the result, methane hydrates are no longer considered one of the tipping points in the climate system, and according to the IPCC Sixth Assessment Report, no "detectable" impact on the global temperatures will occur in this century through this mechanism.

Metallurgy

 * Category:Metallurgy
 * Category:History of metallurgy
 * Category:Metallurgical processes
 * Category:Alloys
 * Category:Precious metal alloys


 * Beneficiation (@Mineral processing): any process that improves (benefits) the economic value of the ore by removing the gangue minerals, which results in a higher grade product (ore concentrate) and a waste stream (tailings). Types of separation: Disaggregation: Dense media separation (DMS) is used to further separate the desired ore from rocks and gangue minerals. This will stratify the crushed aggregate by density making separation easier. Physical separation: gravity separation, flotation, and magnetic separation, DMS. Chemical separation: froth flotation, leaching, and electrowinning are the most common types; Hydrophobic particles will rise to the top of the solution to be skimmed off; Changes to pH in the solution.
 * Gangue (/ɡæŋ/): commercially worthless material that surrounds, or is closely mixed with, a wanted mineral in an ore deposit. It is thus distinct from overburden, which is the waste rock or materials overlying an ore or mineral body that are displaced during mining without being processed, and from tailings, which is rock already stripped of valuable minerals. The separation of valuable mineral from gangue minerals is known as mineral processing, mineral dressing, or ore dressing.


 * Brass: alloy of copper (Cu) and zinc (Zn), in proportions which can be varied to achieve different colours and mechanical, electrical, and chemical properties, but copper typically has the larger proportion. In use since prehistoric times, it is a substitutional alloy: atoms of the two constituents may replace each other within the same crystal structure. Brass is similar to bronze, another copper alloy that uses tin instead of zinc. Both bronze and brass may include small proportions of a range of other elements including arsenic (As), lead (Pb), phosphorus (P), aluminium (Al), manganese (Mn), and silicon (Si). Historically, the distinction between the two alloys has been less consistent and clear, and increasingly museums use the more general term "copper alloy" . Properties: Brass is more malleable than bronze or zinc. The relatively low melting point of brass (900 to 940 °C) and its flow characteristics make it a relatively easy material to cast. By varying the proportions of copper and zinc, the properties of the brass can be changed, allowing hard and soft brasses. The density of brass is 8.4 to 8.73 g/cm³. Germicidal and antimicrobial applications. History: Early copper-zinc alloys, Roman world, Medieval period, Africa, Renaissance and post-medieval Europe.


 * Bloomery: type of metallurgical furnace once used widely for smelting iron from its oxides. The bloomery was the earliest form of smelter capable of smelting iron. Bloomeries produce a porous mass of iron and slag called a bloom. The mix of slag and iron in the bloom, termed sponge iron, is usually consolidated and further forged into wrought iron. Blast furnaces, which produce pig iron, have largely superseded bloomeries.


 * Patina: thin layer that variously forms on the surface of copper, brass, bronze and similar metals and metal alloys (tarnish produced by oxidation or other chemical processes) or certain stones and wooden furniture (sheen produced by age, wear, and polishing), or any similar acquired change of a surface through age and exposure. Additionally, the term is used to describe the aging of high-quality leather. Patinas can provide a protective covering to materials that would otherwise be damaged by corrosion or weathering. They may also be aesthetically appealing.


 * Colored gold: name given to any gold that has been treated using techniques to change its natural color. Pure gold is slightly reddish yellow in color, but colored gold can come in a variety of different colors by alloying it with different elements.
 * Alloys with silver and copper in various proportions, producing white, yellow, green and red golds. These are typically malleable alloys.
 * Intermetallic compounds, producing blue and purple golds, as well as other colors. These are typically brittle, but can be used as gems and inlays.
 * Surface treatments, such as oxide layers.
 * Electrum: naturally occurring alloy of gold and silver, with trace amounts of copper and other metals. Its color ranges from pale to bright yellow, depending on the proportions of gold and silver. It has been produced artificially, and is also known as "green gold". Electrum was used as early as the third millennium BC in Old Kingdom of Egypt, sometimes as an exterior coating to the pyramidions atop ancient Egyptian pyramids and obelisks. It was also used in the making of ancient drinking vessels. The first known metal coins made were of electrum, dating back to the end of the 7th century or the beginning of the 6th century BC.


 * Riotinto-Nerva mining basin: Spanish mining area located in the northeast of the province of Huelva (Andalusia), which has its main population centers in the municipalities of El Campillo, Minas de Riotinto and Nerva, in the region of the Cuenca Minera. It is also part of the Iberian Pyrite Belt. Although there is evidence of this type of activity in the area during protohistoric times, it was not until Roman times when an organized exploitation of its deposits took place. After the activity of the mines was resumed in the Modern Age, the Riotinto basin experienced its peak between the end of the 19th century and the middle of the 20th century under the management of the British Rio Tinto Company Limited. A significant industrial and demographic boom took place during those years. Nowadays, the mineral extraction activity continues, mainly in the Cerro Colorado, although without reaching the production levels it had in the past.

Polymers

 * Category:Polymer chemistry

{q.v. }


 * Copolymer: polymer derived from more than one species of monomer. The polymerization of monomers into copolymers is called copolymerization. Copolymers obtained by copolymerization of two monomer species are sometimes called bipolymers. Those obtained from three and four monomers are called terpolymers and quaterpolymers, respectively. Commercial copolymers include acrylonitrile butadiene styrene (ABS), styrene/butadiene co-polymer (SBR), nitrile rubber, styrene-acrylonitrile, styrene-isoprene-styrene (SIS) and ethylene-vinyl acetate, all formed by chain-growth polymerization. Another production mechanism is step-growth polymerization, used to produce the nylon-12/6/66 copolymer of nylon 12, nylon 6 and nylon 66, as well as the copolyester family. Linear copolymers consist of a single main chain, and include alternating copolymers, statistical copolymers and block copolymers. Branched copolymers consist of a single main chain with one or more polymeric side chains, and can be grafted, star shaped or have other architectures.


 * Polyethylene (PE; polyethene): most common plastic in use today; primarily used for packaging (plastic bags, plastic films, geomembranes, containers including bottles, etc.). As of 2017, over 100 million tonnes of polyethylene resins are being produced annually, accounting for 34% of the total plastics market.
 * Polypropylene (PP): thermoplastic polymer used in a wide variety of applications. It is produced via chain-growth polymerization from the monomer propylene. Polypropylene belongs to the group of polyolefins and is partially crystalline and non-polar. Its properties are similar to polyethylene, but it is slightly harder and more heat resistant. It is a white, mechanically rugged material and has a high chemical resistance. Polypropylene is the second-most widely produced commodity plastic (after polyethylene). Many plastic items for medical or laboratory use can be made from polypropylene because it can withstand the heat in an autoclave.
 * Polycarbonate (PC): group of thermoplastic polymers containing carbonate groups in their chemical structures. Polycarbonates used in engineering are strong, tough materials, and some grades are optically transparent. They are easily worked, molded, and thermoformed.


 * High-performance plastics: meet higher requirements than standard or engineering plastics. They are more expensive and used in smaller amounts. There are many synonyms for the term high-performance plastics, such as: high temperature plastics, high-performance polymers, high performance thermoplastics or high-tech plastics. The name high temperature plastics is in use due to their continuous service temperature (CST), which is always higher than 150°C by definition.


 * Polysulfone: family of high performance thermoplastics. These polymers are known for their toughness and stability at high temperatures. Technically used polysulfones contain an aryl-SO₂-aryl subunit. Due to the high cost of raw materials and processing, polysulfones are used in specialty applications and often are a superior replacement for polycarbonates. Polysulfone (PSU), polyethersulfone (PES) and polyphenylene sulfone (PPSU). They can be used in the temperature range from -100 to +200 °C and are used for electrical equipment, in vehicle construction and medical technology.
 * Polyvinylidene fluoride (polyvinylidene difluoride; PVDF): highly non-reactive thermoplastic fluoropolymer produced by the polymerization of vinylidene difluoride. PVDF is a specialty plastic used in applications requiring the highest purity, as well as resistance to solvents, acids and hydrocarbons.

Materials

 * Category:Materials
 * Category:Refractory materials
 * Category:Refractory metals


 * Refractory metals: class of metals that are extraordinarily resistant to heat and wear. The expression is mostly used in the context of materials science, metallurgy and engineering. The definition of which elements belong to this group differs. The most common definition includes five elements: two of the fifth period (niobium and molybdenum) and three of the sixth period (tantalum, tungsten, and rhenium). They all share some properties, including a melting point above 2000 °C and high hardness at room temperature. They are chemically inert and have a relatively high density. Their high melting points make powder metallurgy the method of choice for fabricating components from these metals.

Nanotechnology, microtechnology

 * Template:Microtechnology
 * Microelectromechanical systems (MEMS): technology of very small devices; merges at the nano-scale into nanoelectromechanical systems (NEMS) and nanotechnology. MEMS are also referred to as micromachines (in Japan), or micro systems technology – MST (in Europe). Components between 1 to 100 µm in size; MEMS devices generally range in size from 20 µm to ~1 mm; usually consist of the microprocessor and several components that interact with the surroundings such as microsensors. Because of the large surface area to volume ratio of MEMS, surface effects such as electrostatics and wetting dominate over volume effects such as inertia or thermal mass. Materials for MEMS manufacturing: silicon, polymers, metals, ceramics (nitrides of silicon, aluminium and titanium, silicon carbide...). MEMS basic processes: Deposition processes (Physical vapor deposition ("PVD"): Sputtering; chemical vapor deposition ("CVD")), Patterning (Lithography), Photolithography (Electron beam lithography, Diamond patterning), Etching processes (Wet etching (Isotropic etching, Anisotropic etching, HF etching, Electrochemical etching), Dry etching, Vapor etching (Xenon difluoride etching), Plasma etching (Sputtering, Reactive ion etching (RIE)), Die preparation). MEMS manufacturing technologies: Bulk micromachining, Surface micromachining, High aspect ratio (HAR) silicon micromachining.
 * Microtechnology: ~1 µm. While electronics now provide the ‘brains’ for today’s advanced systems and products, micromechanical devices can provide the sensors and actuators — the eyes and ears, hands and feet — which interface to the outside world.
 * LIGA (de: Lithographie, Galvanoformung, Abformung = "Lithography, Electroplating, and Molding"): fabrication technology used to create high-aspect-ratio microstructures. X-Ray LIGA uses X-rays produced by a synchrotron to create high-aspect ratio structures. UV LIGA is a more accessible method which uses ultraviolet light to create structures with relatively low aspect ratios.
 * Deep reactive-ion etching: Bosch process (Robert Bosch GmbH).
 * Nanoelectromechanical system (NEMS): devices integrating electrical and mechanical functionality on the nanoscale; typically integrate transistor-like nanoelectronics with mechanical actuators, pumps, or motors, and may thereby form physical, biological, and chemical sensors. Materials: Carbon allotropes (diamond, carbon nanotubes, graphene).


 * Micro-Opto-Electro-Mechanical Systems (MOEMS): MEMS merged with Micro-optics which involves sensing or manipulating optical signals on a very small size scale using integrated mechanical, optical, and electrical systems
 * Bio-MEMS (biomedical (or biological) microelectromechanical systems):science and technology of operating at the microscale for biological and biomedical applications, which may or may not include any electronic or mechanical functions. Bio-MEMS is more focused on mechanical parts and microfabrication technologies made suitable for biological applications; lab-on-a-chip is concerned with miniaturization and integration of laboratory processes and experiments into single (often microfluidic) chips; micro total analysis systems may not have biological applications in mind, and are usually dedicated to chemical analysis. Approaches: Materials (Silicon and glass, Plastics and polymers, Biological materials, Paper), Electrokinetics, Microfluidics. Bio-MEMS as Miniaturized Biosensors: Micromechanical sensors, Electrical and electrochemical sensors, Optical sensors. Bio-MEMS for diagnostics: Genomic and proteomic microarrays, Oligonucleotide chips, cDNA microarray, Peptide and protein microarrays, PCR chips, Point-of-care-diagnostic devices (Sample conditioning, Sample fractionation). Bio-MEMS in tissue engineering: Cell culture, Stem-cell engineering (Biochemical factors, Fluid shear stress, Cell–ECM interactions, Cell–cell interactionsEmbryoid body formation and organization), Assisted reproductive technologies. Bio-MEMS in medical implants and surgery: Implantable microelectrodes, Microtools for surgery, Drug delivery.
 * Lab-on-a-chip
 * Total analysis system (TAS)


 * History of nanotechnology: early 2000s also saw the beginnings of commercial applications of nanotechnology, although these were limited to bulk applications of nanomaterials rather than the transformative applications envisioned by the field. There's Plenty of Room at the Bottom; K. Eric Drexler; Invention of scanning probe microscopy. Fullerenes were discovered in 1985. The National Nanotechnology Initiative is USA federal nanotechnology research and development program. Initial commercial applications: titanium dioxide and zinc oxide nanoparticles in sunscreen, cosmetics and some food products; silver nanoparticles in food packaging, clothing, disinfectants and household appliances such as Silver Nano; carbon nanotubes for stain-resistant textiles; and cerium oxide as a fuel catalyst.
 * There's Plenty of Room at the Bottom: An Invitation to Enter a New Field of Physics: lecture given by physicist Richard Feynman at the annual American Physical Society meeting at Caltech in 1959.12.29. Feynman considered the possibility of direct manipulation of individual atoms as a more powerful form of synthetic chemistry than those used at the time. Although versions of the talk were reprinted in a few popular magazines, it went largely unnoticed and did not inspire the conceptual beginnings of the field of nanotechnology. Beginning in the 1980s, nanotechnology advocates cited it to establish the scientific credibility of their work.


 * Impact of nanotechnology: extends from its medical, ethical, mental, legal and environmental applications, to fields such as engineering, biology, chemistry, computing, materials science, and communications. Major benefits of nanotechnology include improved manufacturing methods, water purification systems, energy systems, physical enhancement, nanomedicine, better food production methods, nutrition and large-scale infrastructure auto-fabrication. Regulatory bodies such as the United States Environmental Protection Agency and the Health and Consumer Protection Directorate of the European Commission have started dealing with the potential risks of nanoparticles. Nanotoxicology: extremely small size of nanomaterials also means that they are much more readily taken up by the human body than larger sized particles.


 * Nanobiotechnology (bionanotechnology, nanobiology): intersection of nanotechnology and biology. Given that the subject is one that has only emerged very recently, bionanotechnology and nanobiotechnology serve as blanket terms for various related technologies. Concepts that are enhanced through nanobiology include: nanodevices, nanoparticles, and nanoscale phenomena that occurs within the discipline of nanotechnology; imagine and create systems that can be used for biological research. Biologically inspired nanotechnology uses biological systems as the inspirations for technologies not yet created; learn from eons of evolution that have resulted in elegant systems that are naturally created; applying nanotools to relevant medical/biological problems and refining these applications. Developing new tools for the medical and biological fields is another primary objective in nanotechnology. The imaging of native biomolecules, biological membranes, and tissues is also a major topic for the nanobiology researchers; use of cantilever array sensors and the application of nanophotonics for manipulating molecular processes in living cells. Use of microorganisms to synthesize functional nanoparticles; microorganisms can change the oxidation state of metals; explore novel applications, for example, the biosynthesis of metal nanomaterials . In contrast to chemical and physical methods, microbial processes for synthesizing nanomaterials can be achieved in aqueous phase under gentle and environmentally benign conditions; focus in current green bionanotechnology research towards sustainable development. Nanobiotechnology is essentially miniaturized biotechnology, whereas bionanotechnology is a specific application of nanotechnology
 * DNA nanotechnology: design and manufacture of artificial nucleic acid structures for technological uses.
 * Nanomotor: molecular or nanoscale device capable of converting energy into movement. It can typically generate forces on the order of piconewtons. Nanomotors are the focus of research for their ability to overcome microfluidic dynamics present at low Reynold's numbers. Scallop Theory explains that nanomotors must break symmetry to produce motion at low Reynold's numbers. In addition, Brownian motion must be considered because particle-solvent interaction can dramatically impact the ability of a nanomotor to traverse through a liquid. This can pose a significant problem when designing new nanomotors. Nanotube and nanowire motors. Enzymatic nanomotors. Helical nanomotors. Current-driven nanomotors (Classical). Quantum effects in current-driven nanomotors.


 * Nanometrology: subfield of metrology, concerned with the science of measurement at the nanoscale level.
 * Nanomanufacturing: both the production of nanoscaled materials, which can be powders or fluids, and the manufacturing of parts "bottom up" from nanoscaled materials or "top down" in smallest steps for high precision, used in several technologies such as laser ablation, etching and others.


 * Template:Nanotechnology implications
 * Template:Nanomaterials
 * Template:Nanoelectronics


 * Dynamic random access memory


 * DNA origami: 2D/3D structures from DNA, the more complex the structure - the longer it takes to fold.


 * Nanoparticle tracking analysis (NTA): visualizing and analyzing particles in liquids that relates the rate of Brownian motion to particle size; rate of movement is related only to the viscosity and temperature of the liquid; determination of a size distribution profile of small particles with a diameter of approximately 10-1000 nm in liquid suspension; technique is used in conjunction with an ultramicroscope and a laser illumination unit that together allow small particles in liquid suspension to be visualized moving under Brownian motion. Analysis of particles at the lowest end of this range is possible only for particles composed of materials with a high refractive index, such gold and silver.


 * Chemical & Engineering News (C&EN): weekly magazine published by the American Chemical Society, providing professional and technical information in the fields of chemistry and chemical engineering; information on recent news and research in these fields, career and employment information, business and industry news, government and policy news, funding in these fields, and special reports

Research & design, companies
{q.v. User:Kazkaskazkasako/Books/EECS}
 * Infineon Technologies
 * National Physical Laboratory (United Kingdom)

Crystallography, X-ray crystallography

 * Category:Condensed matter physics
 * Category:Crystallography
 * Category:X-ray crystallography

{q.v. }
 * User:Kazkaskazkasako/Books/Mathematics
 * User:Kazkaskazkasako/Books/Mathematics Topology; Symmetry


 * X-ray crystallography
 * Crystal structure: Unit cell (Within the unit cell is the asymmetric unit, smallest unit the crystal can be divided into using the crystallographic symmetry operations of the space group. The asymmetric unit is also what is generally solved when solving a structure of a molecule or protein by X-ray crystallography.)
 * : smallest unit of volume that contains all of the structural and symmetry information and that by translation can reproduce a pattern in all of space.
 * , : smallest unit of volume that contains all of the structural information and that by application of the symmetry operations can reproduce the unit cell.
 * Biological unit (also, @Proteopedia: biological assembly, @PDB wiki: functional unit): smallest number of protein molecules which form a biologically active (e.g. catalytically active) unit (or biologically relevant as found in the cells). Functional form of the protein.


 * Structure solution methods:
 * Maximum entropy method


 * Crystallographic restriction theorem: rotational symmetries of a (3D) crystal are limited to 2-fold, 3-fold, 4-fold, and 6-fold (crystallography forbids 5 fold, 7 fold, and higher rotational symmetries).


 * But a phase in between the glass and crystal does exist:
 * Quasicrystal
 * Aperiodic tiling
 * Modified Bragg diffraction in quasicrystals


 * Crystal system: In crystallography, the terms crystal system, crystal family, and lattice system each refer to one of several classes of space groups, lattices, point groups, or crystals. Crystal systems, crystal families, and lattice systems are similar but slightly different, and there is widespread confusion between them: in particular the trigonal crystal system is often confused with the rhombohedral lattice system, and the term "crystal system" is sometimes used to mean "lattice system" or "crystal family". Space groups and crystals are divided into 7 crystal systems according to their point groups, and into 7 lattice systems according to their Bravais lattices. Five of the crystal systems are essentially the same as five of the lattice systems, but the hexagonal and trigonal crystal systems differ from the hexagonal and rhombohedral lattice systems . The six crystal families are formed by combining the hexagonal and trigonal crystal systems into one hexagonal family, to eliminate this confusion. See the table where "crystal system" from the left and "lattice system" from the right go into "point groups" on the left and into "bravais lattices" on the right and they meet as "space groups": see how "space groups" are split into 3 groups by this meeting from the left (trigonal/hexagonal crystal systems) and the right (rhombohedral/hexagonal lattice systems).
 * Crystal system: Crystal classes=32 (table of 32 point groups); Lattice systems=7 (subdivided into 14 Bravais lattices). Crystallographic symmetries forbid quite some of the molecular symmetries and only 230 remain (in 3D) (i.e., although molecules have many possible symmetries, they can crystallize only in very few symmetries; everything else is not crystals).


 * Space group (in crystallography: crystallographic or Fedorov groups; in dimensions other than 3: Bieberbach groups):
 * Notation for space groups: number (in IUCr tables), International symbol or Hermann–Mauguin notation, Hall notation, Schoenflies notation, Shubnikov symbol, 2D:Orbifold notation and 3D:Fibrifold notation, Coxeter notation
 * Classification systems for space groups: see the table explaining how space groups are classified into classes (reminds of biological classification into species (correspond to crystallographic space groups), genuses, classes, families...) in 3D: (Crystallographic) space group types [230] ⇒ Affine space group types [219] ⇒ Arithmetic crystal classes [73] ⇒ ((geometric) Crystal classes [32] ⇒ Crystal systems [7] OR Bravais flocks [14] ⇒ Lattice systems [7]) ⇒ Crystal families [6]. Other classifications: Conway, Delgado Friedrichs, and Huson et al. (2001)::
 * Space groups in other dimensions: table of dimension, # lattice types (OEIS: A004030), # crystallographic point groups (OEIS: A004028), # crystallographic space group types (OEIS: A006227), # affine space group types (OEIS: A004029)
 * Table of space groups in 3 dimensions: table of: groupings international notation numbers, crystal systems [7], point groups (in international and Schoenflies notations) [32], crystallographic space groups (international short symbol) [230]. Also explanation how to obtain lattice systems from crystal systems (some of space group of the trigonal crystal systems have names beginning with "R" and are rhombohedral lattice systems; the other trigonal crystal systems belong to the hexagonal lattice system); Bravais lattices.


 * Molecular symmetry in chemistry: symmetry present in molecules and the classification of these molecules according to their symmetry. Molecular symmetry is a fundamental concept in chemistry, as it can be used to predict or explain many of a molecule's chemical properties, such as its dipole moment and its allowed spectroscopic transitions. To do this it is necessary to classify the states of the molecule using the irreducible representations from the character table of the symmetry group of the molecule. Many university level textbooks on physical chemistry, quantum chemistry, spectroscopy and inorganic chemistry devote a chapter to symmetry. The framework for the study of molecular symmetry is provided by group theory, and in particular irreducible representation theory. Symmetry is useful in the study of molecular orbitals, with applications such as Hückel method, ligand field theory, and the Woodward-Hoffmann rules. Another framework on a larger scale is the use of crystal systems to describe crystallographic symmetry in bulk materials. Common point groups: C1, Cs, Ci, C∞v, D∞h, C2, C3, C2h, C3h, C2v, C3v, C4v, C5v, D2, D3, D2h, D3h, D4h, D5h, D6h, D7h, D8h, D2d, D3d, D4d, D5d, S4, Td,  Th, Oh, Ih,

Electromagnetism

 * Category:Electromagnetism
 * Category:Magnetism
 * Category:Magnetic ordering


 * Vacuum permittivity ($ε_{0}$ (pronounced "epsilon nought" or "epsilon zero"); permittivity of free space, electric constant, distributed capacitance of the vacuum): value of the absolute dielectric permittivity of classical vacuum. CODATA value
 * (farads per meter), with a relative uncertainty of

The value of ε0 is defined by the formula
 * $$ \varepsilon_0 =\frac {1}{\mu_0 c^2}$$, μ0 is the parameter that international Standards Organizations call the "magnetic constant" (commonly called vacuum permeability or the permeability of free space).
 * Vacuum permeability (vacuum permeability, permeability of free space, permeability of vacuum, magnetic constant): magnetic permeability in a classical vacuum. It is a physical constant, conventionally written as  μ0. CODATA value
 * , with a relative uncertainty of
 * Terminology: Standards organizations have recently moved to magnetic constant as the preferred name for μ0.


 * Magnetic susceptibility: measure of how much a material will become magnetized in an applied magnetic field. It is the ratio of magnetization $M$ (magnetic moment per unit volume) to the applied magnetizing field intensity $H$. This allows a simple classification, into two categories, of most materials' responses to an applied magnetic field: an alignment with the magnetic field, $χ > 0$, called paramagnetism, or an alignment against the field, $χ < 0$, called diamagnetism.
 * Ferromagnetism: basic mechanism by which certain materials (such as iron) form permanent magnets, or are attracted to magnets. In physics, several different types of magnetism are distinguished. Ferromagnetism (along with the similar effect ferrimagnetism) is the strongest type and is responsible for the common phenomenon of magnetism in magnets encountered in everyday life. Substances respond weakly to magnetic fields with three other types of magnetism—paramagnetism, diamagnetism, and antiferromagnetism—but the forces are usually so weak that they can be detected only by sensitive instruments in a laboratory. The attraction between a magnet and ferromagnetic material is "the quality of magnetism first apparent to the ancient world, and to us today".
 * Paramagnetism: form of magnetism whereby certain materials are weakly attracted by an externally applied magnetic field, and form internal, induced magnetic fields in the direction of the applied magnetic field. In contrast with this behavior, diamagnetic materials are repelled by magnetic fields and form induced magnetic fields in the direction opposite to that of the applied magnetic field.
 * Superparamagnetism: form of magnetism, which appears in small ferromagnetic or ferrimagnetic nanoparticles. In sufficiently small nanoparticles, magnetization can randomly flip direction under the influence of temperature. The typical time between two flips is called the Néel relaxation time.
 * Iron oxide nanoparticles: diameters between about 1 and 100 nm. They have attracted extensive interest due to their superparamagnetic properties and their potential applications in many fields.
 * Curie temperature (Curie point): temperature above which certain materials lose their permanent magnetic properties, which can (in most cases) be replaced by induced magnetism.


 * Magnetite (Iron(II,III) oxide (Fe2+Fe3+2O4), Fe3O4): mineral and one of the main iron ores. One of the oxides of iron, and is ferrimagnetic; it is attracted to a magnet and can be magnetized to become a permanent magnet itself. It is the most magnetic of all the naturally occurring minerals on Earth. Naturally magnetized pieces of magnetite, called lodestone, will attract small pieces of iron, which is how ancient peoples first discovered the property of magnetism.
 * Ferrite (magnet): ceramic material made by mixing and firing large proportions of iron(III) oxide (Fe2O3, rust) blended with small proportions of one or more additional metallic elements, such as strontium, barium, manganese, nickel, and zinc. They are ferrimagnetic, meaning they can be magnetized or attracted to a magnet. Unlike other ferromagnetic materials, most ferrites are not electrically conductive, making them useful in applications like magnetic cores for transformers to suppress eddy currents. Hard ferrites have high coercivity, so are difficult to demagnetize. They are used to make permanent magnets for applications such as refrigerator magnets, loudspeakers, and small electric motors. Soft ferrites have low coercivity, so they easily change their magnetization and act as conductors of magnetic fields. They are used in the electronics industry to make efficient magnetic cores called ferrite cores for high-frequency inductors, transformers and antennas, and in various microwave components.

Electrodynamics, electromagnetic radiation

 * Category:Electromagnetism
 * Category:Electrodynamics
 * Category:Electromagnetic radiation
 * Category:Optical metrology
 * Category:Radiometry


 * Poynting vector: represents the directional energy flux (the energy transfer per unit area per unit time) or power flow of an electromagnetic field. The SI unit of the Poynting vector is the watt per square metre (W/m²). The Poynting vector is used throughout electromagnetics in conjunction with Poynting's theorem, the continuity equation expressing conservation of electromagnetic energy, to calculate the power flow in electromagnetic fields.


 * Attenuation coefficient (linear attenuation coefficient, narrow-beam attenuation coefficient; old term: Extinction coefficient): how easily a volume of material can be penetrated by a beam of light, sound, particles, or other energy or matter. The SI unit of attenuation coefficient is the reciprocal metre (m⁻¹). Most commonly, the quantity measures the value of downward e-folding distance of the original intensity as the energy of the intensity passes through a unit (e.g. one meter) thickness of material, so that an attenuation coefficient of 1 m⁻¹ means that after passing through 1 metre, the radiation will be reduced by a factor of e, and for material with a coefficient of 2 m⁻¹, it will be reduced twice by e, or e².

Biophysics, physical chemistry

 * Category:Biophysics
 * Category:Physical chemistry
 * Category:Atomic, molecular, and optical physics
 * Category:Chemical kinetics
 * Category:Electrochemistry
 * Category:Equilibrium chemistry
 * Category:Molecular physics
 * Category:Intermolecular forces
 * Category:Quantum chemistry
 * Category:Surface chemistry
 * Category:Thermodynamics
 * Category:Stochastic processes
 * Category:Stochastic simulation
 * Category:Theoretical chemistry
 * Category:Computational chemistry


 * Force field (chemistry):
 * $$\ E_{\text{bonded}} = E_{\text{bond}} + E_{\text{angle}} + E_{\text{dihedral}}$$
 * $$\ E_{\text{nonbonded}} = E_{\text{electrostatic}} + E_{\text{van der Waals}} $$


 * Lennard-Jones potential is an approximation:
 * $$V(r) = 4\epsilon \left[ \left(\frac{\sigma}{r}\right)^{12} - \left(\frac{\sigma}{r}\right)^{6} \right],$$
 * Van der Waals force (London dispersion force is part of Van der Waals): r−6


 * Phase rule: proposed by Josiah Willard Gibbs in his landmark paper titled On the Equilibrium of Heterogeneous Substances, published from 1875 to 1878.
 * $$F\;=\;C\;-\;P\;+\;2$$
 * F is the number of degrees of freedom, C is the number of components and P is the number of phases in thermodynamic equilibrium with each other.


 * Triple point: of a substance is the temperature and pressure at which the three phases (gas, liquid, and solid) of that substance coexist in thermodynamic equilibrium. It is that temperature and pressure at which the sublimation, fusion, and vaporisation curves meet. Helium-4 is unusual in that it has no sublimation/deposition curve and therefore no triple points where its solid phase meets its gas phase. Instead, it has a vapor-liquid-superfluid point, a solid-liquid-superfluid point, a solid-solid-liquid point, and a solid-solid-superfluid point. The triple point of water was used to define the kelvin, the base unit of thermodynamic temperature in the International System of Units (SI). The value of the triple point of water was fixed by definition, rather than by measurement, but that changed with the 2019 redefinition of SI base units.
 * Critical point (thermodynamics)


 * Lambda point: temperature at which normal fluid helium (helium I) makes the transition to superfluid helium II (approximately 2.17 K at 1 atm). The lowest pressure at which He-I and He-II can coexist is the vapor−He-I−He-II triple point at 2.1768 K (−270.9732 °C) and 5.0418 kPa (0.049759 atm), which is the "saturated vapor pressure" at that temperature (pure helium gas in thermal equilibrium over the liquid surface, in a hermetic container). The highest pressure at which He-I and He-II can coexist is the bcc−He-I−He-II triple point with a helium solid at 1.762 K (−271.388 °C), 29.725 atm (3,011.9 kPa).


 * Macromolecular crowding: alters the properties of molecules in a solution when high concentrations of macromolecules are present. Such conditions occur routinely in living cells, e.g., the cytosol of Escherichia coli contains about 300–400 mg/mL of macromolecules; these high concentrations of macromolecules reduce the volume of solvent available for other molecules in the solution, which has the result of increasing their effective concentrations


 * Photofragment-ion imaging (Product Imaging): experimental technique for making measurements of the velocity of product molecules or particles following a chemical reaction or the photodissociation of a parent molecule. The method uses a two-dimensional detector, usually a microchannel plate, to record the arrival positions of state-selected ions created by resonantly enhanced multi-photon ionization (REMPI). Improvements to the Product Imaging Technique:
 * Velocity Map Imaging
 * Three-Dimensional (3D) Ion Imaging
 * Centroiding
 * DC Slice Imaging
 * Electron Imaging
 * Photoelectron photoion coincidence spectroscopy (PEPICO): combination of photoionization mass spectrometry and photoelectron spectroscopy. Free molecules from a gas-phase sample are ionized by incident vacuum ultraviolet (VUV) radiation. In the ensuing photoionization, a cation and a photoelectron are formed for each sample molecule. The mass of the photoion is determined by time-of-flight mass spectrometry, whereas, in current setups, photoelectrons are typically detected by velocity map imaging.
 * Resonance-enhanced multiphoton ionization (REMPI): technique applied to the spectroscopy of atoms and small molecules. In practice, a tunable laser can be used to access an excited intermediate state. The selection rules associated with a two-photon or other multiphoton photoabsorption are different from the selection rules for a single photon transition. The REMPI technique typically involves a resonant single or multiple photon absorption to an electronically excited intermediate state followed by another photon which ionizes the atom or molecule. The light intensity to achieve a typical multiphoton transition is generally significantly larger than the light intensity to achieve a single photon photoabsorption. Because of this, a subsequent photoabsorption is often very likely.


 * Gillespie algorithm: generates a statistically correct trajectory (possible solution) of a stochastic equation. It was created by Joseph L. Doob and others (circa 1945), presented by Dan Gillespie in 1976, and popularized in 1977 in a paper where he uses it to simulate chemical or biochemical systems of reactions efficiently and accurately using limited computational power (see stochastic simulation). As computers have become faster, the algorithm has been used to simulate increasingly complex systems. The algorithm is particularly useful for simulating reactions within cells, where the number of reagents is low and keeping track of the position and behaviour of individual molecules is computationally feasible. Mathematically, it is a variant of a dynamic Monte Carlo method and similar to the kinetic Monte Carlo methods. It is used heavily in computational systems biology.


 * Dry ice: solid form of carbon dioxide. It is commonly used as it does not have a liquid state and sublimates directly from the solid state to the gas state. It is used primarily as a cooling agent, but is also used in fog machines at theatres for dramatic effects. Its advantages include lower temperature than that of water ice and not leaving any residue (other than incidental frost from moisture in the atmosphere). It is useful for preserving frozen foods (such as ice cream) where mechanical cooling is unavailable. Dry ice sublimates at 194.7 K (−78.5 °C) at Earth atmospheric pressure . This extreme cold makes the solid dangerous to handle without protection from frostbite injury. While generally not very toxic, the outgassing from it can cause hypercapnia (abnormally elevated carbon dioxide levels in the blood) due to buildup in confined locations.

Thermodynamics

 * Category:Thermodynamics
 * Category:Chemical engineering thermodynamics

{q.v. User:Kazkaskazkasako/Books/All}


 * Conjugate variables (thermodynamics): such as temperature and entropy or pressure and volume. In fact, all thermodynamic potentials are expressed in terms of conjugate pairs. The product of two quantities that are conjugate has units of energy or sometimes power.
 * Thermodynamic potential: scalar quantity used to represent the thermodynamic state of a system. The concept of thermodynamic potentials was introduced by Pierre Duhem in 1886. Josiah Willard Gibbs in his papers used the term fundamental functions. One main thermodynamic potential that has a physical interpretation is the internal energy U. It is the energy of configuration of a given system of conservative forces (that is why it is a potential) and only has meaning with respect to a defined set of references (or data).


 * Principle of minimum energy:
 * The maximum entropy principle: For a closed system with fixed internal energy (i.e. an isolated system ), the entropy' is maximized at equilibrium.
 * The minimum energy principle: For a closed system with fixed entropy, the total energy is minimized at equilibrium.


 * Zeotropic mixture: mixture with components that have different boiling points. For example, nitrogen, methane, ethane, propane, and isobutane constitute a zeotropic mixture. Individual substances within the mixture do not evaporate or condense at the same temperature as one substance. In other words, the mixture has a temperature glide, as the phase change occurs in a temperature range of about four to seven degrees Celsius, rather than at a constant temperature. On temperature-composition graphs, this temperature glide can be seen as the temperature difference between the bubble point and dew point. For zeotropic mixtures, the temperatures on the bubble (boiling) curve are between the individual component's boiling temperatures. When a zeotropic mixture is boiled or condensed, the composition of the liquid and the vapor changes according to the mixtures's temperature-composition diagram.
 * Azeotrope (constant boiling point mixture): mixture of two or more liquids whose proportions cannot be altered or changed by simple distillation. This happens because when an azeotrope is boiled, the vapour has the same proportions of constituents as the unboiled mixture.
 * Azeotrope tables: various binary and ternary mixtures of solvents. The data include the composition of a mixture by weight (in binary azeotropes, when only one fraction is given, it is the fraction of the second component), the boiling point (b.p.) of a component, the boiling point of a mixture, and the specific gravity (relative density) of the mixture. Boiling points are reported at a pressure of 760 mm Hg unless otherwise stated. Where the mixture separates into layers, values are shown for upper (U) and lower (L) layers. The data were obtained from Lange's 10th edition and CRC Handbook of Chemistry and Physics 44th edition unless otherwise noted (see color code table). Binary azeotropes: water, ethanol, methanol (MeOH), n-propanol, isopropyl alcohol (IPA), acetic acid, formic acid, ethylene glycol, acetone, benzene, glycerol, Miscellaneous azeotrope pairs.

HVAC: heating, ventilation, and air conditioning

 * Category:Heating, ventilation, and air conditioning
 * Category:Heating
 * Category:Heat pumps


 * Thermoacoustic heat engine: thermoacoustic devices which use high-amplitude sound waves to pump heat from one place to another (this requires work, which is provided by the loudspeaker) or use a heat difference to produce work in the form of sound waves (these waves can then be converted into electrical current the same way as a microphone does).

Electrochemistry

 * Category:Electrochemistry
 * Category:Electroanalytical chemistry
 * Category:Electroanalytical methods
 * Category:Electrophoresis
 * Category:Electrochemical cells
 * Category:Electrolysis
 * Category:Electrolytes


 * Template:Galvanic cells
 * Electrochemical cell: device capable of either generating electrical energy from chemical reactions or using electrical energy to cause chemical reactions. The electrochemical cells which generate an electric current are called voltaic or galvanic cells and those that generate chemical reactions, via electrolysis for example, are called electrolytic cells.
 * Lead–acid battery: type of rechargeable battery first invented in 1859 by French physicist Gaston Planté. It is the first type of rechargeable battery ever created. Compared to modern rechargeable batteries, lead–acid batteries have relatively low energy density. Despite this, their ability to supply high surge currents means that the cells have a relatively large power-to-weight ratio. These features, along with their low cost, make them attractive for use in motor vehicles to provide the high current required by starter motors. Lead-acid batteries suffer from relatively short cycle lifespan (usually less than 500 deep cycles) and overall lifespan (due to the "double sulfation" in the discharged state).
 * Lithium polymer battery: rechargeable battery of lithium-ion technology using a polymer electrolyte instead of a liquid electrolyte. High conductivity semisolid (gel) polymers form this electrolyte. These batteries provide higher specific energy than other lithium battery types and are used in applications where weight is a critical feature, such as mobile devices, radio-controlled aircraft and some electric vehicles.
 * Lithium iron phosphate battery (LFP; lithium ferro-phosphate): type of lithium-ion battery using lithium iron phosphate (LiFePO₄) as the cathode material, and a graphitic carbon electrode with a metallic backing as the anode. Because of their lower cost, high safety, low toxicity, long cycle life and other factors, LFP batteries are finding a number of roles in vehicle use, utility-scale stationary applications, and backup power. LFP batteries are cobalt-free. As of September 2022, LFP type battery market share for EV's reached 31%, and of that, 68% was from Tesla and Chinese EV maker BYD production alone. Chinese manufacturers currently hold a near monopoly of LFP battery type production, however, with patents having started to expire in 2022 and the increased demand for cheaper EV batteries, LFP type production is expected to rise further to surpass NMC type batteries in 2028.
 * Sodium-ion battery: working principle and cell construction are almost identical with those of lithium-ion battery (LIB) types, but replace lithium with sodium. Sodium-ion batteries are a potential alternative to lithium-based battery technologies, largely due to sodium's lower cost and greater availability. Since SIBs use abundant and cheap materials, they are expected to be less expensive than LIBs. The environmental impacts of SIBs are also lower. Although SIBs are heavier and larger than LIBs, they are feasible for stationary energy storage systems where the weight and volume are less crucial.


 * Gel electrophoresis: method for separation and analysis of macromolecules (DNA, RNA and proteins) and their fragments, based on their size and charge.


 * Voltammetry: information about an analyte is obtained by measuring the current as the potential is varied. Three electrodes: (1) working electrode; (2) auxiliary electrode; (3) reference electrode.


 * Electro-osmosis (lectroosmotic flow; electroendosmosis): motion of liquid induced by an applied potential across a porous material, capillary tube, membrane, microchannel, or any other fluid conduit. Because electroosmotic velocities are independent of conduit size, as long as the electrical double layer is much smaller than the characteristic length scale of the channel, electroosmotic flow is most significant when in small channels. Electroosmotic flow is an essential component in chemical separation techniques, notably capillary electrophoresis.

Physics literature

 * Category:Physics literature
 * Category:Historical physics publications
 * Category:Physics books
 * Category:Physics textbooks


 * List of important publications in physics: Applied physics: Accelerator physics, Biophysics (Cell, Mathematical, Medical, Molecular, Neurophysics, Plant), Geophysics, Physics of computation, Plasma physics; Astronomy and astrophysics: Astrophysics, Cosmology; Atomic and molecular physics; Classical mechanics: Fluid dynamics; Computational physics; Condensed matter physics: Polymer physics; Electromagnetism; General physics; Mathematical physics: Pre-Modern (Classical) mathematical physics, Nonlinear dynamics and chaos; Optics; Nuclear and particle physics: Nuclear physics, Particle physics; Quantum mechanics: Quantum field theory; Relativity: Special, General; Statistical mechanics and thermodynamics

Isaac Newton:
 * Philosophiæ Naturalis Principia Mathematica (The Mathematical Principles of Natural Philosophy; Latin: 1687.07.05; English: 1728): book by Isaac Newton that expounds Newton's laws of motion and his law of universal gravitation. After Newton's death in 1727, the relatively accessible character of its writing encouraged the publication of an English translation in 1728 (by persons still unknown, not authorised by Newton's heirs). It appeared under the English title A Treatise of the System of the World. This had some amendments relative to Newton's manuscript of 1685, mostly to remove cross-references that used obsolete numbering to cite the propositions of an early draft of Book 1 of the Principia.
 * Opticks: or, A Treatise of the Reflexions, Refractions, Inflexions and Colours of Light (English: 1704; Latin: 1706): Opticks differs in many respects from the Principia. It was first published in English rather than in the Latin used by European philosophers, contributing to the development of a vernacular science literature . This marks a significant transition in the history of the English Language.

Werner Heisenberg:
 * Über quantentheoretische Umdeutung kinematischer und mechanischer Beziehungen ("Quantum theoretical re-interpretation of kinematic and mechanical relations"; 1925) was a breakthrough article in quantum mechanics written by Werner Heisenberg, which appeared in Zeitschrift für Physik in September 1925.

Paul Dirac:
 * The Principles of Quantum Mechanics (1930): influential monograph on quantum mechanics first published by Oxford University Press. Dirac gives an account of quantum mechanics by "demonstrating how to construct a completely new theoretical framework from scratch"; "problems were tackled top-down, by working on the great principles, with the details left to look after themselves". It leaves classical physics behind after the first chapter, presenting the subject with a logical structure. Its 82 sections contain 785 equations with no diagrams . Dirac is credited with developing the subject "particularly in Cambridge and Göttingen between 1925–1927" (Farmelo).


 * What Is Life? The Physical Aspect of the Living Cell (1944): book written for the lay reader by physicist Erwin Schrödinger.

Obsolete theories in physics

 * Category:Obsolete theories in physics


 * Cubical atom: early atomic model in which electrons were positioned at the eight corners of a cube in a non-polar atom or molecule. This theory was developed in 1902 by Gilbert N. Lewis and published in 1916 in the article "The Atom and the Molecule" and used to account for the phenomenon of valency. Lewis' theory was based on Abegg's rule. It was further developed in 1919 by Irving Langmuir as the cubical octet atom.



Chemistry

 * Category:Chemistry
 * Category:Geochemistry {q.v. }


 * List of important publications in chemistry: Foundations: The Sceptical Chymist (Robert Boyle, 1661); Traité Élémentaire de Chimie (Antoine Lavoisier, 1789); Méthode de Nomenclature Chimique (Guyton de Morveau, L. B.; Lavoisier, A. L.; Berthollet, C. L.; de Fourcroy, A. F., 1787); A New System of Chemical Philosophy (John Dalton, 1808–1827); The Dependence Between the Properties of the Atomic Weights of the Elements (Dmitri Mendeleev, 1869). Organic chemistry. Inorganic chemistry. Inorganic chemistry. Physical Chemistry: Physical Chemistry (P. W. Atkins 1st Ed 1978, 10th Ed 2014 (with Julio de Paula from 7th Ed 2002)), Physical Chemistry (Berry, Rice and Ross; 1st Ed 1980, 2nd Ed 2000), Methods in Physical Chemistry (Schäfer, Schmidt, 2012). Biochemistry. Analytical chemistry. Polymer chemistry. Environmental chemistry. Chemical thermodynamics. Chemical thermodynamics: On the Equilibrium of Heterogeneous Substances (Willard Gibbs; Trans. Conn. Acad., Vol. III, pp. 108–248, 1876; pp. 343–524, 1878). Electrochemistry. Theoretical chemistry, quantum chemistry and computational chemistry. Supramolecular chemistry. Medicinal chemistry.


 * Syneresis (chemistry): extraction or expulsion of a liquid from a gel, as when serum drains from a contracting clot of blood. Another example of syneresis is the collection of whey on the surface of yogurt. Syneresis can also be observed when the amount of diluent in a swollen polymer exceeds the solubility limit as the temperature changes. A household example of this is the counter intuitive expulsion of water from dry gelatin when the temperature increases.

Periodic table
{q.v. }


 * Template:Periodic table (metalloid) & Metalloid: chemical element with properties that are in between or a mixture of those of metals and nonmetals, and which is considered to be difficult to classify unambiguously as either a metal or a nonmetal; no standard definition of a metalloid nor is there agreement as to which elements are appropriately classified as such. Main metalloids: B, Si, Ge, As, Sb, Te; less commonly recognized metalloids: C, Al, Se, Po, At. On a standard periodic table all of these elements can be found in or near a diagonal region of the p-block, having its main axis anchored by boron at one end and astatine at the other. Metalloids and their compounds instead find common use in glasses, alloys and semiconductors.
 * Template:Periodic table (metalloid border) & Dividing line between metals and nonmetals (amphoteric line, metal-nonmetal line, metalloid line, semimetal line, staircase, Zintl border/line): can be found, in varying configurations, on some representations of the periodic table of the elements. Elements to the lower left of the line generally display increasing metallic behavior; elements to the upper right display increasing nonmetallic behavior.


 * Periodic table blocks spdf (32 column).svg
 * Block (periodic table): of the periodic table is a set of elements unified by the orbitals their valence electrons or vacancies lie in. The term appears to have been first used by Charles Janet. Each block is named after its characteristic orbital: s-block, p-block, d-block, and f-block. Characteristics: There is an approximate correspondence between this nomenclature of blocks, based on electronic configuration, and sets of elements based on chemical properties. The s-block and p-block together are usually considered main-group elements, the d-block corresponds to the transition metals, and the f-block encompasses nearly all of the lanthanides (like lanthanum) and the actinides (like actinium). Not everyone agrees on the exact membership of each set of elements. For example, the group 12 elements zinc, cadmium, and mercury are often regarded as main group, rather than transition group, because they are chemically and physically more similar to the p-block elements than the other d-block elements. The group 3 elements are sometimes considered main group elements due to their similarities to the s-block elements. Groups (columns) in the f-block (between groups 2 and 3) are not numbered. f-block: f-block elements are unified by mostly having one or more electrons in an inner f-orbital. Of the f-orbitals, six have six lobes each, and the seventh looks like a dumbbell with a donut with two rings. They can contain up to seven pairs of electrons hence the block occupies fourteen columns in the periodic table. They are not assigned group numbers, since vertical periodic trends cannot be discerned in a "group" of two elements.

Sets of chemical elements

 * Category:Sets of chemical elements


 * Names for sets of chemical elements
 * Alkali metals – The metals of group 1: Li, Na, K, Rb, Cs, Fr.
 * Alkaline earth metals – The metals of group 2: Be, Mg, Ca, Sr, Ba, Ra.
 * Transition elements (transition metals) – Elements in groups 3 to 11 or 3 to 12 (the latter equalling the d-block).
 * Pnictogens – The elements of group 15: N, P, As, Sb, Bi. (Mc had not yet been named when the 2005 IUPAC Red Book was published, and its chemical properties are not yet experimentally known.)
 * Chalcogens – The elements of group 16: O, S, Se, Te, Po. (Lv had not yet been named when the 2005 IUPAC Red Book was published, and its chemical properties are not yet experimentally known.)
 * Halogens – The elements of group 17: F, Cl, Br, I, At. (Ts had not yet been named when the 2005 IUPAC Red Book was published, and its chemical properties are not yet experimentally known.)
 * Noble gases – The elements of group 18: He, Ne, Ar, Kr, Xe, Rn. (Og had not yet been named when the 2005 IUPAC Red Book was published, and its chemical properties are not yet experimentally known.)
 * Lanthanides (lanthanoids) – Elements 57–71: La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu.
 * Actinides (actinoids) – Elements 89–103: Ac, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md, No, Lr.
 * Rare-earth metals – Sc, Y, plus the lanthanides.
 * Inner transition elements – f-block elements.
 * Main group elements – Elements in groups 1–2 or 13–18, except hydrogen.


 * Category:Halogens
 * Pseudohalogen: polyatomic analogues of halogens, whose chemistry, resembling that of the true halogens, allows them to substitute for halogens in several classes of chemical compounds.

Nomenclature of chemistry

 * International Union of Pure and Applied Chemistry (IUPAC; HQ=Research Triangle Park, NC, USA; registered in Zürich, CH): international federation of National Adhering Organizations that represents chemists in individual countries; member of ICSU/ISC.
 * National Adhering Organizations: organizations that work as the authoritative power over chemistry in an individual country. Their importance can be seen by their involvement in IUPAC. Currently: 57 [2013].
 * IUPAC books: IUPAC publishes many books, which contain its complete list of definitions.
 * Blue Book (Nomenclature of Organic Chemistry; A Guide to IUPAC Nomenclature of Organic Compounds): collection of recommendations on organic chemical nomenclature
 * Gold Book (Compendium of Chemical Terminology): containing internationally accepted definitions for terms in chemistry; initiated by Victor Gold
 * Green Book (Quantities, Units and Symbols in Physical Chemistry): compilation of terms and symbols widely used in the field of physical chemistry; table of physical constants, tables listing the properties of elementary particles, chemical elements, and nuclides, and information about conversion factors that are commonly used in physical chemistry
 * Orange Book (Compendium of Analytical Nomenclature): internationally accepted definitions for terms in analytical chemistry. It has traditionally been published in an orange cover.
 * Purple Book (Compendium of Macromolecular Terminology and Nomenclature): about the nomenclature of polymers
 * Red Book (Nomenclature of Inorganic Chemistry): collection of recommendations on inorganic chemical nomenclature.
 * Silver Book (Compendium of Terminology and Nomenclature of Properties in Clinical Laboratory Sciences)
 * White Book (Biochemical Nomenclature and Related Documents (1992)): definitions pertaining to biochemical research compiled jointly by IUPAC and the International Union of Biochemistry and Molecular Biology


 * Chemical Abstracts Service (CAS): division of the American Chemical Society. It is a source of chemical information.
 * CAS Registry Number (CASRN or CAS Number): unique numerical identifier assigned by CAS to every chemical substance described in the open scientific literature (currently including those described from at least 1957 through the present), including organic and inorganic compounds, minerals, isotopes, alloys and nonstructurable materials (UVCBs, of unknown, variable composition, or biological origin). The Registry is updated with an approximate 15,000 additional new substances daily [2016].

Chemical structures, chemical formulas

 * Category:Chemical structures
 * Category:Chemical formulas


 * Chemical formula: way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as parentheses, dashes, brackets, commas and plus (+) and minus (−) signs. These are limited to a single typographic line of symbols, which may include subscripts and superscripts. A chemical formula is not a chemical name, and it contains no words. Although a chemical formula may imply certain simple chemical structures, it is not the same as a full chemical structural formula. Chemical formulae can fully specify the structure of only the simplest of molecules and chemical substances, and are generally more limited in power than chemical names and structural formulae. Molecular formulae indicate the simple numbers of each type of atom in a molecule, with no information on structure.
 * Types: Empirical formula, Molecular formula, Structural formula, Condensed formula
 * Law of composition: Chemical names in answer to limitations of chemical formulae (Chemical nomenclature), Polymers in condensed formulae, Ions in condensed formulae
 * Isotopes
 * Trapped atoms: @ buckminsterfullerene (C₆₀)
 * Non-stoichiometric chemical formulae
 * General forms for organic compounds
 * oHill system: system of writing empirical chemical formulae, molecular chemical formulae and components of a condensed formula such that the number of carbon atoms in a molecule is indicated first, the number of hydrogen atoms next, and then the number of all other chemical elements subsequently, in alphabetical order of the chemical symbols. When the formula contains no carbon, all the elements, including hydrogen, are listed alphabetically.


 * Skeletal formula (line-angle formula, shorthand formula): of an organic compound is a type of molecular structural formula that serves as a shorthand representation of a molecule's bonding and some details of its molecular geometry. A skeletal formula shows the skeletal structure or skeleton of a molecule, which is composed of the skeletal atoms that make up the molecule. An early form of this representation was first developed by organic chemist August Kekulé, while the modern form is closely related to and influenced by the Lewis structure of molecules and their valence electrons. Hence they are sometimes termed Kekulé structures or Lewis–Kekulé structures. Skeletal formulae have become ubiquitous in organic chemistry, partly because they are relatively quick and simple to draw, and also because the curved arrow notation used for discussions of reaction mechanisms and electron delocalization can be readily superimposed. Other types of representation, such as Newman projection, Haworth projection or Fischer projection, also look somewhat similar to skeletal formulae. However, there are slight differences in the conventions used, and the reader needs to be aware of them in order to understand the structural details encoded in the depiction. While skeletal and conformational structures are also used in organometallic and inorganic chemistry, the conventions employed also differ somewhat.
 * Implicit carbon and hydrogen atoms: The linear geometry at sp hybridized atoms is normally depicted by line segments meeting at 180°. Where this involves two double bonds meeting (an allene or cumulene), the bonds are separated by a dot.
 * Explicit heteroatoms and hydrogen atoms
 * Pseudoelement symbols:
 * General symbols: X, L / Ln, M / Met, E / El, Nu, Z, D, T
 * Alkyl groups: R, Me, Et, Pr / n-Pr, i-Pr, All, Bu / n-Bu, i-Bu, s-Bu, t-Bu, Pn, Np, Cy, Ad (1-adamantyl), Tr / Trt (trityl)
 * Aromatic and unsaturated substituents: Ar, Het, Bn / Bzl (benzyl), Dipp, Mes, Ph / Φ / or φ (phenyl)
 * Functional groups: Ac, Bz, OBz, Piv, Bt, Im, NPhth
 * Sulfonyl/sulfonate groups: Bs, Ms, Ns, Tf, Nf, Ts
 * Protecting groups: Boc (t-butoxycarbonyl); Cbz / Z (carboxybenzyl); Fmoc (fluorenylmethoxycarbonyl); Alloc (allyloxycarbonyl); Troc (trichloroethoxycarbonyl); TMS, TBDMS, TES, TBDPS, TIPS (various silyl ether groups), PMB, MOM, THP
 * Multiple bonds
 * Benzene rings
 * Stereochemistry
 * Hydrogen bonds

Theoretical chemistry

 * Category:Chemistry
 * Category:Theoretical chemistry
 * Category:Quantum chemistry
 * Category:Medicinal chemistry
 * Category:Stereochemistry]
 * Category:Molecules

{q.v. User:Kazkaskazkasako/Books/Mathematics} Topology; Symmetry


 * Molecular_symmetry, all symmetry elements applying to the molecules (only a subset of all 3D symmetries), infinite possibilities, limited only by (covalent) bond (number? and) strength, or there is no limitation of number of atoms bonded, as it could branch out more and more from the symmetry core to change the symmetry? Chiral: $$C_n, D_n, T, O, I$$.


 * Isostere. Classical isosteres : molecules or ions with the same number of atoms or the same number of valence electrons or both; later revised to include compounds with similarly reactive electron shells (e.g. H+ and F-; H+ and Na+; CO2 and N2O; Si and C). Non-Classical isosteres : do not obey the above classifications, but they still produce similar biological effects in vivo; may be made up of similar atoms, but their structures do not follow an easily-definable set of rules (e.g. methyl, amide, hydroxyl groups)
 * Bioisostere: substituents or groups with similar physical or chemical properties which produce broadly similar biological properties to a chemical compound; in drug design and pharmaceutical sciences, the purpose of exchanging one bioisostere for another is to enhance the desired biological or physical properties of a compound without making significant changes in chemical structure; used to reduce toxicity or modify the activity of the lead compound, and may alter the metabolism of the lead.


 * Isoelectronicity: several molecular entities (atoms, molecules, ions) are described as being isoelectronic with each other if they have the same number of electrons or a similar electron configuration and the same structure (number and connectivity of atoms), regardless of the nature of the elements involved. Valence isoelectronic: molecular entities have the same number of valence electrons or a similar electron configuration, but may have a different number of atoms or a different bonding. Amino acids selenocysteine, cysteine and serine are also considered (at least valence) isoelectronic.


 * Category:Molecular geometry


 * Isostructural chemical compounds have similar chemical structures; isomorphous when used in relation to crystal structures is essentially synonymous. E.g. benzene ~ borazine ("inorganic benzene"; BH and NH alternate in (BH)3(NH)3); indium(I) bromide ~ β-thallium(I) iodide: both have distorted rock salt structure; I-gold(I) bromide ~ gold(I) chloride.

Chemical bond

 * Category:Chemical bonding
 * Category:Binding energy


 * Chemical bond: lasting attraction between atoms, ions or molecules that enables the formation of chemical compounds. The bond may result from the electrostatic force between oppositely charged ions as in ionic bonds or through the sharing of electrons as in covalent bonds. The strength of chemical bonds varies considerably; there are "strong bonds" or "primary bonds" such as covalent, ionic and metallic bonds, and "weak bonds" or "secondary bonds" such as dipole–dipole interactions, the London dispersion force and hydrogen bonding. Strong chemical bonds: Ionic bond, Covalent bond (Single and multiple bonds, Coordinate covalent bond (dipolar bond)), Metallic bonding. Intermolecular bonding. Theories of chemical bonding.


 * Covalent bond classification method (CBC, LXZ notation): published by M. L. H. Green in 1995 as a solution for the need to describe covalent compounds such as organometallic complexes in a way that is not prone to limitations resulting from the definition of oxidation state. Instead of simply assigning a charge to an atom in the molecule (i.e. the oxidation state), the covalent bond classification method analyzes the nature of the ligands surrounding the atom of interest, which is often a transition metal. According to this method, there are three basic types of interactions that allow for coordination of the ligand. The three types of interaction are classified according to whether the ligating group donates two, one, or zero electrons. These three classes of ligands are respectively given the symbols L, X, and Z.


 * Bond-dissociation energy (BDE): one measure of the strength of a chemical bond A−B. It can be defined as the standard enthalpy change when A−B is cleaved by homolysis to give fragments A and B, which are usually radical species. The enthalpy change is temperature-dependent, and the bond-dissociation energy is often defined to be the enthalpy change of the homolysis at 0 K, although the enthalpy change at 298 K (standard conditions) is also a frequently encountered parameter. Nevertheless, bond dissociation energy measurements are challenging and are subject to considerable error. The majority of currently known values are accurate to within ±1 or 2 kcal/mol (4–10 kJ/mol). Moreover, values measured in the past, especially before the 1970s, can be especially unreliable and have been subject to revisions on the order of 10 kcal/mol (e.g., benzene C–H bonds, from 103 kcal/mol in 1965 to the modern accepted value of 112.9(5) kcal/mol). To convert a molar BDE to the energy needed to dissociate the bond per molecule, the conversion factor 23.060 kcal/mol (96.485 kJ/mol) for each eV can be used. Bond energy. Strongest bonds and weakest bonds: strongest single bonds are Si−F bonds. The BDE for H₃Si−F is 152 kcal/mol, almost 50% stronger than the H₃C−F bond (110 kcal/mol). The BDE for F₃Si−F is even larger, at 166 kcal/mol. One consequence to these data are that many reactions generate silicon fluorides, such as glass etching, deprotection in organic synthesis, and volcanic emissions. The strength of the bond is attributed to the substantial electronegativity difference between silicon and fluorine, which leads to a substantial contribution from both ionic and covalent bonding to the overall strength of the bond. The C−C single bond of diacetylene (HC≡C−C≡CH) linking two sp-hybridized carbon atoms is also among the strongest, at 160 kcal/mol. The strongest bond for a neutral compound, including multiple bonds, is found in carbon monoxide at 257 kcal/mol.

Stereochemistry

 * Category:Stereochemistry
 * Category:Isomerism


 * Meso compound (meso isomer): non-optically active member of a set of stereoisomers, at least two of which are optically active. This means that despite containing two or more stereogenic centers, the molecule is not chiral. A meso compound is "superposable" on its mirror image. Two objects can be superposed if all aspects of the objects coincide and it does not produce a "(+)" or "(-)" reading when analyzed with a polarimeter.
 * Tartaric acid: white, crystalline organic acid that occurs naturally in many fruits, most notably in grapes, but also in bananas, tamarinds, and citrus. Its salt, potassium bitartrate, commonly known as cream of tartar, develops naturally in the process of fermentation. It is commonly mixed with sodium bicarbonate and is sold as baking powder used as a leavening agent in food preparation. Tartaric acid has been known to winemakers for centuries. Tartaric acid played an important role in the discovery of chemical chirality. This property of tartaric acid was first observed in 1832 by Jean Baptiste Biot, who observed its ability to rotate polarized light. Louis Pasteur continued this research in 1847 by investigating the shapes of sodium ammonium tartrate crystals, which he found to be chiral. By manually sorting the differently shaped crystals, Pasteur was the first to produce a pure sample of levotartaric acid . Forms of tartaric acid: Levotartaric acid ((2S,3S)-tartaric acid), Dextrotartaric acid ((2R,3R)-tartaric acid), Mesotartaric acid, Mesotartaric acid ((2R,3S)-tartaric acid).


 * Tautomer: structural isomers (constitutional isomers) of chemical compounds that readily interconvert. This reaction commonly results in the relocation of a hydrogen atom. Tautomerism is for example relevant to the behavior of amino acids and nucleic acids, two of the fundamental building blocks of life. The concept of tautomerizations is called tautomerism. The chemical reaction interconverting the two is called tautomerization. Care should be taken not to confuse tautomers with depictions of "contributing structures" in chemical resonance . Tautomers are distinct chemical species that can be distinguished by their differing atomic connectivities, molecular geometries, and physicochemical and spectroscopic properties, whereas resonance forms are merely alternative Lewis structure (valence bond theory) depictions of a single chemical species, whose true structure is best described as the "average" of the idealized, hypothetical geometries implied by these resonance forms. Prototropy: the most common form of tautomerism and refers to the relocation of a hydrogen atom. Prototropic tautomerism may be considered a subset of acid-base behavior. Prototropic tautomers are sets of isomeric protonation states with the same empirical formula and total charge. Valence tautomerism: type of tautomerism in which single and/or double bonds are rapidly formed and ruptured, without migration of atoms or groups. It is distinct from prototropic tautomerism, and involves processes with rapid reorganisation of bonding electrons.

Quantum chemistry, exclusion principles

 * Category:Quantum chemistry
 * Category:Pauli exclusion principle


 * Pauli exclusion principle: states that two or more identical particles with half-integer spins (i.e. fermions) cannot occupy the same quantum state within a quantum system simultaneously. This principle was formulated by Austrian physicist Wolfgang Pauli in 1925 for electrons, and later extended to all fermions with his spin–statistics theorem of 1940. In the case of electrons in atoms, it can be stated as follows: it is impossible for two electrons of a poly-electron atom to have the same values of the four quantum numbers: n, the principal quantum number; $\ell$, the azimuthal quantum number; mℓ, the magnetic quantum number; and ms, the spin quantum number. For example, if two electrons reside in the same atomic orbital, then their n, ℓ, and mℓ values are the same; therefore their ms must be different, and thus the electrons must have opposite half-integer spin projections of 1/2 and −1/2.


 * Spherical harmonics ($$Y_\ell^m$$): the angular portion of a set of solutions to Laplace's equation.


 * Molecular orbital theory (MO theory): method for determining molecular structure in which electrons are not assigned to individual bonds between atoms, but are treated as moving under the influence of the nuclei in the whole molecule
 * HOMO/LUMO: HOMO: highest occupied molecular orbital, LUMO: lowest unoccupied molecular orbital
 * Frontier molecular orbital theory: application of MO theory describing HOMO / LUMO interactions.


 * Exchange interaction, aka Pauli repulsion


 * Electron configuration: distribution of electrons of an atom or molecule (or other physical structure) in atomic or molecular orbitals. E.g. Ne 1s2 2s2 2p6. Electronic configurations describe each electron as moving independently in an orbital, in an average field created by all other orbitals. Knowledge of the electron configuration of different atoms is useful in understanding the structure of the periodic table of elements. This is also useful for describing the chemical bonds that hold atoms together. In bulk materials, this same idea helps explain the peculiar properties of lasers and semiconductors. Atoms: Aufbau principle and Madelung rule: Periodic table; Shortcomings of the aufbau principle; Ionization of the transition metal; Other exceptions to Madelung's rule.
 * Relativistic quantum chemistry: combines relativistic mechanics with quantum chemistry to explain elemental properties and structure, especially for the heavier elements of the periodic table. A prominent example of such an explanation is the color of gold: due to relativistic effects, it is not silvery like most other metals. Relativistic effects in chemistry can be considered to be perturbations, or small corrections, to the non-relativistic theory of chemistry, which is developed from the solutions of the Schrödinger equation. Periodic table deviations: Mercury (Hg); Color of gold (Au) and caesium; Lead-acid battery; Inert pair effect.

Acid-base chemistry

 * Category:Acid-base chemistry
 * Category:Acids
 * Category:Superacids
 * Category:Bases
 * Category:Buffer solutions


 * Acid–base reaction: Several concepts exist that provide alternative definitions for the reaction mechanisms involved and their application in solving related problems. Historic acid–base theories: Lavoisier's oxygen theory of acids, Liebig's hydrogen theory of acids. Common acid–base theories:
 * Arrhenius definition: an Arrhenius acid is a substance that dissociates in water to form H+; an Arrhenius base is a substance that dissociates in water to form OH−.
 * Solvent system definition: limitations of the Arrhenius definition is its reliance on water solutions . Albert F. O. Germann, working with liquid, formulated the solvent-based theory in 1925, thereby generalizing the Arrhenius definition to cover aprotic solvents . Germann pointed out that in many solutions, there are ions in equilibrium with the neutral solvent molecules: solvonium: generic name for a positive ion. solvate: generic name for a negative ion.
 * Brønsted–Lowry acid–base theory: Brønsted acid is defined as being able to lose, or "donate" proton (H+) while a Brønsted base is defined as a species with the ability to gain, or "accept," a proton.
 * Lewis acids and bases: molecular entity (and the corresponding chemical species) that is an electron-pair acceptor and therefore able to react with a Lewis base to form a Lewis adduct, by sharing the electron pair furnished by the Lewis base.


 * Acid dissociation constant (Ka, acidity constant, acid-ionization constant): quantitative measure of the strength of an acid in solution
 * Acid strength: strong acid is one that completely ionizes (dissociates) in a solution; weak acid only partially dissociates in a solution.
 * Extremely strong acids (as protonators):
 * Magic acid: FSO3H-SbF5
 * Fluoroantimonic acid : protonates nearly all organic compounds.
 * Superacid: classical definition: acid with an acidity greater than that of 100% pure sulfuric acid


 * Amphoterism: amphoteric compound is a molecule or ion that can react both as an acid and as a base. What exactly this can mean depends on which definitions of acids and bases are being used. The prefix of the word 'amphoteric' is derived from a Greek prefix amphi which means "both". One type of amphoteric species are amphiprotic molecules, which can either donate or accept a proton (H⁺). This is what "amphoteric" means in Brønsted–Lowry acid–base theory. Examples include amino acids and proteins, which have amine and carboxylic acid groups, and self-ionizable compounds such as water. Metal oxides which react with both acids as well as bases to produce salts and water are known as amphoteric oxides. Many metals (such as zinc, tin, lead, aluminium, and beryllium) form amphoteric oxides or hydroxides. Ampholytes are amphoteric molecules that contain both acidic and basic groups and will exist mostly as zwitterions in a certain range of pH. The pH at which the average charge is zero is known as the molecule's isoelectric point. Ampholytes are used to establish a stable pH gradient for use in isoelectric focusing.
 * Amphiprotic molecules: Water: H2O + HCl → H3O+ + Cl− (acid); H2O + NH3 → NH4+ + OH− (base)
 * Oxides: Zinc oxide: ZnO + H2SO4 → ZnSO4 + H2O (with acid)
 * Hydroxides: Alluminium hydroxide: Al(OH)3 +  3 HCl  →   AlCl3  +  3 H2O (neutralizing an acid); Al(OH)3 + NaOH → Na[Al(OH)4] (neutralizing a base)


 * Leveling effect (solvent leveling): effect of solvent on the properties of acids and bases; strength of a strong acid is limited ("leveled") by the basicity of the solvent; strength of a strong base is leveled by the acidity of the solvent


 * Hammett acidity function (H0): measure of acidity that is used for very concentrated solutions of strong acids, including superacids


 * Piranha solution (piranha etch): mixture of sulfuric acid (H2SO4) and hydrogen peroxide (H2O2), used to clean organic residues off substrates. Because the mixture is a strong oxidizing agent, it will remove most organic matter, and it will also hydroxylate most surfaces (add OH groups), making them highly hydrophilic (water-compatible). Piranha solution is used frequently in the microelectronics industry, e.g. to clean photoresist residue from silicon wafers.


 * Triflic acid (trifluoromethanesulfonic acid): sulfonic acid with the chemical formula CF3SO3H. It is one of the strongest known acids. Triflic acid is mainly used in research as a catalyst for esterification. It is a hygroscopic, colorless, slightly viscous liquid and is soluble in polar solvents.

Explosives

 * Category:Energetic materials
 * Category:Explosives


 * Explosive material (explosive; explosive charge): reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. Chemical energy: nitroglycerin or grain dust (grain elevator and grinding mill explosions); pressurized gas; nuclear energy. History: gunpowder (black powder; 9th c. China); nitroglycerin (1847); nitrocellulose, smokeless powder, dynamite, gelignite; WWI: TNT; WWII; modern explosives: C-4, others. Properties of explosive materials: Availability and cost; Sensitivity (impact, friction, heat); Sensitivity to initiation; Velocity of detonation; Stability (Chemical formula - kinetics, Temperature of storage, Exposure to sunlight, Electrical discharge); Power, performance, and strength; Brisance (shattering effect, rapidity with which an explosive reaches its peak pressure (power) is a measure of its brisance); Density; Volatility (vaporization); Hygroscopicity and water resistance; Toxicity; Explosive train; Volume of products of explosion; Oxygen balance (OB% or Ω); Chemical composition (mixture of explosive and clay, silica...); Chemically pure compounds; Mixture of oxidizer and fuel. Classification of explosive materials: By sensitivity: Primary explosive (extremely sensitive to stimuli such as impact, friction, heat, static electricity, or electromagnetic radiation), Secondary explosive (less sensitive than a primary explosive and require substantially more energy to be initiated; e.g. TNT, RDX), Tertiary explosive (blasting agents; so insensitive to shock that they cannot be reliably detonated by practical quantities of primary explosive, and instead require an intermediate explosive booster of secondary explosive); By velocity: low explosives (rate of decomposition proceeds through the material at less than the speed of sound), high explosives (detonate, explosive shock front passes through the material at a supersonic speed).
 * Chemical explosive
 * List of explosives used during World War II: mixtures of TNT, RDX or PETN.
 * Trinitrotoluene (TNT; 2,4,6-trinitrotoluene; 1863): explosive yield of TNT is considered to be the standard measure of strength of bombs and other explosives.
 * Pentaerythritol tetranitrate (PETN, PENT, PENTA, TEN, corpent, penthrite (de: nitropenta); 1891 (used by DE in WWI)): most well known as an explosive; one of the most powerful high explosives known, with a relative effectiveness factor of 1.66; mixed with a plasticizer forms a plastic explosive.
 * RDX ("Research Department Explosive"; cyclonite, hexogen, T4; chemical: cyclotrimethylenetrinitramine; 1898): developed as an explosive which was more powerful than TNT, saw wide use in WWII.

Chemical reactions

 * Category:Chemical reactions
 * Category:Chemical synthesis
 * Category:Hydrogenation
 * Category:Functional groups
 * Category:Protecting groups
 * Category:Sulfonyl groups


 * Protecting group (protective group): introduced into a molecule by chemical modification of a functional group to obtain chemoselectivity in a subsequent chemical reaction. It plays an important role in multistep organic synthesis; deprotection. Protecting groups are more commonly used in small-scale laboratory work and initial development than in industrial production processes because their use adds additional steps and material costs to the process.


 * Process chemistry: arm of pharmaceutical chemistry concerned with the development and optimization of a synthetic scheme and pilot plant procedure to manufacture compounds for the drug development phase. Process chemistry is distinguished from medicinal chemistry. Medicinal chemists are largely concerned with synthesizing a large number of compounds as quickly as possible from easily tunable chemical building blocks (usually for SAR studies). In general, the repertoire of reactions utilized in discovery chemistry is somewhat narrow (for example, the Buchwald-Hartwig amination, Suzuki coupling and reductive amination are commonplace reactions). In contrast, process chemists are tasked with identifying a chemical process that is safe, cost and labor efficient, “green,” and reproducible, among other considerations. Oftentimes, in searching for the shortest, most efficient synthetic route, process chemists must devise creative synthetic solutions that eliminate costly functional group manipulations and oxidation/reduction steps . Consideration in process chemistry: Material cost; Conversion cost: Atom economy, Yield, Volume-time output, Environmental factor (e-factor) and process mass intensity (PMI), Quality service level (QSL); EcoScale. Additional topics: Transition-metal catalysis and organocatalysis; Biocatalysis and enzymatic engineering; Continuous/flow manufacturing.


 * Asymmetric hydrogenation: adds two atoms of hydrogen to a target (substrate) molecule with three-dimensional spatial selectivity. Critically, this selectivity does not come from the target molecule itself, but from other reagents or catalysts present in the reaction. This allows spatial information (what chemists refer to as chirality) to transfer from one molecule to the target, forming the product as a single enantiomer. The chiral information is most commonly contained in a catalyst and, in this case, the information in a single molecule of catalyst may be transferred to many substrate molecules, amplifying the amount of chiral information present. Similar processes occur in nature, where a chiral molecule like an enzyme can catalyse the introduction of a chiral centre to give a product as a single enantiomer, such as amino acids, that a cell needs to function. By imitating this process, chemists can generate many novel synthetic molecules that interact with biological systems in specific ways, leading to new pharmaceutical agents and agrochemicals.


 * Salt metathesis reaction (double displacement reaction): chemical process involving the exchange of bonds between two reacting chemical species which results in the creation of products with similar or identical bonding affiliations. AB + CD -> AD + CB  The bond between the reacting species can be either ionic or covalent. Classically, these reactions result in the precipitation of one product.


 * Retrosynthetic analysis: technique for solving problems in the planning of organic syntheses. This is achieved by transforming a target molecule into simpler precursor structures regardless of any potential reactivity/interaction with reagents. Each precursor material is examined using the same method. This procedure is repeated until simple or commercially available structures are reached. These simpler/commercially available compounds can be used to form a synthesis of the target molecule. The goal of retrosynthetic analysis is structural simplification. Often, a synthesis will have more than one possible synthetic route. Retrosynthesis is well suited for discovering different synthetic routes and comparing them in a logical and straightforward fashion. A database may be consulted at each stage of the analysis, to determine whether a component already exists in the literature.
 * Disconnection: retrosynthetic step involving the breaking of a bond to form two (or more) synthons
 * Retron: minimal molecular substructure that enables certain transformations
 * Retrosynthetic tree: directed acyclic graph of several (or all) possible retrosyntheses of a single target
 * Synthon: fragment of a compound that assists in the formation of a synthesis, derived from that target molecule.
 * Target: desired final compound.
 * Transform: reverse of a synthetic reaction; the formation of starting materials from a single product.
 * Synthon: hypothetical unit within a target molecule that represents a potential starting reagent in the retroactive synthesis of that target molecule. The term was coined in 1967 by E. J. Corey. He noted in 1988 that the "word synthon has now come to be used to mean synthetic building block rather than retrosynthetic fragmentation structures". Because synthons are charged, when placed into a synthesis a neutral form is found commercially instead of forming and using the potentially very unstable charged synthons.


 * Acyl group: moiety derived by the removal of one or more hydroxyl groups from an oxoacid, including inorganic acids. It contains a double-bonded oxygen atom and an organyl group (R−C=O) or hydrogen in the case of formyl group (H−C=O). In organic chemistry, the acyl group (IUPAC name alkanoyl if the organyl group is alkyl) is usually derived from a carboxylic acid, in which case it has the formula R−C(=O)−, where R represents an organyl group or hydrogen. A general acyl group in a ketone, as an acylium cation, as an acyl radical, an aldehyde, ester or amide.
 * Acetyl group (Ac): −COCH3 and the structure −C(=O)−CH₃.
 * Aldehyde: organic compound containing a functional group with the structure R−CH=O. The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl group.


 * Sulfonyl group: refer either to a functional group found primarily in sulfones, or to a substituent obtained from a sulfonic acid by the removal of the hydroxyl group, similarly to acyl groups. Sulfonyl groups can be written as having the general formula R−S(=O)2−R′, where there are two double bonds between the sulfur and oxygen.
 * Tosyl group (toluenesulfonyl group; Ts): univalent functional group with the chemical formula −SO₂−C₆H₄−CH₃. It consists of a tolyl group, −C₆H₄−CH₃, joined to a sulfonyl group, −SO₂−, with the open valence on sulfur. This group is usually derived from the compound tosyl chloride, CH₃C₆H₄SO₂Cl (abbreviated TsCl), which forms esters and amides of toluenesulfonic acid, CH₃C₆H₄SO₂OH (abbreviated TsOH). The para orientation illustrated (p-toluenesulfonyl) is most common, and by convention tosyl without a prefix refers to the p-toluenesulfonyl group.
 * Mesylate: salt or ester of methanesulfonic acid (CH₃SO₃H). Related to mesylate is the mesyl (Ms) or methanesulfonyl (CH₃SO₂) functional group. Methanesulfonyl chloride is often referred to as mesyl chloride. Whereas mesylates are often hydrolytically labile, mesyl groups, when attached to nitrogen, are resistant to hydrolysis.
 * Triflyl group (trifluoromethanesulfonyl group; Tf): R−SO₂CF₃ and structure R−S(=O)₂−CF₃.


 * Suzuki reaction (Suzuki coupling): classified as a cross-coupling reaction, where the coupling partners are a boronic acid and an organohalide and the catalyst is a palladium(0) complex. It was first published in 1979 by Akira Suzuki, and he shared the 2010 Nobel Prize in Chemistry with Richard F. Heck and Ei-ichi Negishi for their contribution to the discovery and development of palladium-catalyzed cross-couplings in organic synthesis. It is widely used to synthesize polyolefins, styrenes, and substituted biphenyls. Carbon-carbon single bond is formed by coupling a halide (R¹-X) with an organoboron species (R²-BY₂) using a palladium catalyst and a base. The organoboron species is usually synthesized by hydroboration or carboboration, allowing for rapid generation of molecular complexity.

Carbon and nitrogen (CN) compounds, found in outer space

 * Category:Cyanides
 * Category:Isocyanides


 * Template:Molecules detected in outer space


 * Hydrogen cyanide (HCN): colorless, extremely poisonous, and flammable liquid that boils slightly above room temperature, at 25.6 °C; produced on an industrial scale and is a highly valued precursor to many chemical compounds ranging from polymers to pharmaceuticals. Occurrence: HCN is obtainable from fruits that have a pit, such as cherries, apricots, apples, and bitter almonds, from which almond oil and flavoring are made; HCN on Titan; HCN on the young Earth; HCN in mammals; HCN and the origin of life; HCN in space.
 * Protonated hydrogen cyanide (HCNH⁺): molecular ion of astrophysical interest. It also exists in the condensed state when formed by superacids. Astronomical detections: Initial interstellar detection; Subsequent interstellar detections; Solar System bodies: while not directly detected via spectroscopy, the existence of HCNH+ has been inferred to exist in the atmosphere of Saturn's largest moon, Titan, based on data from the Ion and Neutral Mass Spectrometer (INMS) instrument aboard the Cassini space probe.
 * Hydrogen isocyanide (HNC): minor tautomer of hydrogen cyanide (HCN). Its importance in the field of astrochemistry is linked to its ubiquity in the interstellar medium. Molecular properties: HNC−HCN tautomerism: As HNC is higher in energy than HCN by 3920 cm−1 (46.9 kJ/mol), one might assume that the two would have an equilibrium ratio ( [ H N C ] [ H C N ] ) e q $\left ( \frac{[HNC]}{[HCN]} \right )_{observed}$  at temperatures below 100 Kelvin of 10−25. However, observations show a very different conclusion; ratio is in fact on the order of unity in cold environments. This is because of the potential energy path of the tautomerization reaction; there is an activation barrier on the order of roughly 12,000 cm−1 for the tautomerization to occur, which corresponds to a temperature at which HNC would already have been destroyed by neutral-neutral reactions. Significance in the interstellar medium: HNC is intricately linked to the formation and destruction of numerous other molecules of importance in the interstellar medium—aside from the obvious partners HCN, protonated hydrogen cyanide (HCNH⁺), and cyanide (CN), HNC is linked to the abundances of many other compounds, either directly or through a few degrees of separation. As such, an understanding of the chemistry of HNC leads to an understanding of countless other species—HNC is an integral piece in the complex puzzle representing interstellar chemistry.


 * Isocyanic acid (HNCO; H–N=C=O): colourless substance, volatile and poisonous, with a boiling point of 23.5 °C. It is the predominant tautomer of cyanic acid H–O–C≡N. Occurrence: Isocyanic acid has been detected in many kinds of interstellar environments. Isocyanic acid is also present in various forms of smoke, including smog and cigarette smoke. It was detected using mass spectrometry, and easily dissolves in water, posing a health risk to the lungs.
 * Cyanate ([O=C=N]−, OCN−): anion, also refers to any salt containing it, such as ammonium cyanate.

Carbon compounds

 * Category:Carbon compounds
 * Category:Carbonates
 * Category:Carbonyl compounds
 * Category:Inorganic carbon compounds


 * Oxocarbon (oxide of carbon): chemical compound consisting only of carbon and oxygen. Linear carbon dioxides. Linear carbon monoxides. Radialene-type cyclic polyketones. New oxides. Polymeric carbon oxides. Fullerene oxides and ozonides.


 * Carbon suboxide (tricarbon dioxide, C₃O₂, O=C=C=C=O): oxide of carbon, four cumulative double bonds make it a cumulene. It is one of the stable members of the series of linear oxocarbons O=Cₙ=O, which also includes carbon dioxide (CO₂) and pentacarbon dioxide (C₅O₂). Although if carefully purified it can exist at room temperature in the dark without decomposing, it will polymerize under certain conditions.


 * Mellite: unusual mineral being also an organic chemical. It is chemically identified as an aluminium salt of mellitic acid, and specifically as aluminium benzene hexacarboxylate hydrate, with the chemical formula Al₂C₆(COO)₆·16H₂O. Translucent honey-coloured crystal which can be polished and faceted to form striking gemstones. It crystallizes in the tetragonal system and occurs both in good crystals and as formless masses. It is soft with a Mohs hardness of 2 to 2.5 and has a low specific gravity of 1.6.


 * Tricarbon (1λ2,3λ2-propadiene; catena-tricarbon): colourless gas that only persists in dilution or solution as an adduct. It is one of the simplest unsaturated carbenes. Tricarbon can be found in interstellar space and can be produced in the laboratory by a process called laser ablation.
 * Diazenylium (N2H+): inorganic cation that was one of the first ions to be observed in interstellar clouds. Since then, it has been observed for in several different types of interstellar environments, observations that have several different scientific uses.
 * Dicarbon monoxide (C₂O): molecule that contains two carbon atoms and one oxygen atom. It is a linear molecule that, because of its simplicity, is of interest in a variety of areas

Organic chemistry

 * Category:Organic chemistry
 * Category:Organic compounds
 * Category:Organometallic chemistry


 * Category:Acid–base chemistry
 * Category:Buffers


 * Category:Organophosphorus compounds
 * Category:Phosphorothioates


 * Good's buffers: twenty buffering agents for biochemical and biological research selected and described by Norman Good and colleagues during 1966–1980. Most of the buffers were new zwitterionic compounds prepared and tested by Good and coworkers for the first time, some (MES, ADA, BES, Bicine) were known compounds previously overlooked by biologists. Before Good's work, few hydrogen ion buffers between pH 6 and 8 had been accessible to biologists, and very inappropriate, toxic, reactive and inefficient buffers had often been used. Many Good's buffers became and remain crucial tools in modern biological laboratories.
 * Buffer solution: aqueous solution consisting of a mixture of a weak acid and its conjugate base, or vice versa. Its pH changes very little when a small or moderate amount of strong acid or base is added to it and thus it is used to prevent changes in the pH of a solution. Common buffer compounds used in biology: TAPS, Tris, Tricine, HEPES, TES, MOPS, PIPES, MES...


 * Ethylenediaminetetraacetic acid (EDTA): aminopolycarboxylic acid with the formula [CH₂N(CH₂CO₂H)₂]₂. This white, water-insoluble solid is widely used to bind to iron (Fe²⁺/Fe³⁺) and calcium ions (Ca²⁺), forming water-soluble complexes even at neutral pH. It is thus used to dissolve Fe- and Ca-containing scale as well as to deliver iron ions under conditions where its oxides are insoluble. EDTA is available as several salts, notably disodium EDTA, sodium calcium edetate, and tetrasodium EDTA, but these all function similarly. Uses: Textile industry; Water softener; Scrubbing; Ion-exchange chromatography; Medicine (lead and mercury poisoning): Dentistry, Eyedrops, Analysis (kidney function); Cosmetics; Laboratory applications.
 * TAE buffer: Tris base, acetic acid and EDTA.
 * TBE buffer: Tris base, boric acid and EDTA.
 * LB buffer: lithium borate (lithium hydroxide monohydrate and boric acid); used in agarose electrophoresis: DNA, RNA.

List of compounds with C1-C24 carbons, e.g.:
 * List of compounds with carbon number 1
 * List of compounds with carbon number 2
 * List of compounds with carbon number 3
 * List of compounds with carbon number 4
 * List of compounds with carbon number 10
 * List of compounds with carbon number 12
 * List of compounds with carbon number 14
 * List of compounds with carbon number 16
 * List of compounds with carbon number 18
 * List of compounds with carbon number 20
 * List of compounds with carbon number 24
 * List of compounds with carbon numbers 25–29
 * List of compounds with carbon numbers 30–39
 * List of compounds with carbon numbers 40–49
 * List of compounds with carbon numbers 50–100
 * List of compounds with carbon numbers 40–49
 * List of compounds with carbon numbers 50–100


 * Template:Organophosphorus
 * Thiophosphate (phosphorothioates; PS): chemical compounds and anions with the general chemical formula (x = 0, 1, 2, or 3) and related derivatives where organic groups are attached to one or more O or S. Thiophosphates feature tetrahedral phosphorus(V) centers. Organic: Organothiophosphate. Inorganic: Monothiophosphate, Dithiophosphates, Tri- and tetrathiophosphates, PxSy: binary thiophosphates and polyphosphates.


 * Category:Heterocyclic compounds
 * Heterocyclic compound (ring structure): cyclic compound that has atoms of at least two different elements as members of its ring(s). Heterocyclic chemistry is the branch of organic chemistry dealing with the synthesis, properties, and applications of these heterocycles.


 * Grignard reagent: chemical compound with the general formula R−Mg−X, where X is a halogen and R is an organic group, normally an alkyl or aryl. Grignard compounds are popular reagents in organic synthesis for creating new carbon-carbon bonds. For example, when reacted with another halogenated compound R'−X' in the presence of a suitable catalyst, they typically yield R−R' and the magnesium halide MgXX' as a byproduct; and the latter is insoluble in the solvents normally used. In this aspect, they are similar to organolithium reagents.


 * NanoPutian: series of organic molecules whose structural formulae resemble human forms.

Organometallic chemistry

 * Category:Organometallic chemistry


 * Organolithium reagent: chemical compounds that contain carbon–lithium (C–Li) bonds. These reagents are important in organic synthesis, and are frequently used to transfer the organic group or the lithium atom to the substrates in synthetic steps, through nucleophilic addition or simple deprotonation. Reactivity and applications: As nucleophile (Carbolithiation reactions, Addition to carbonyl compounds, SN2 type reactions); As base (Metalation, Superbases, Asymmetric metalation, Asymmetric metalation, Enolate formation); Lithium–halogen exchange; Transmetalation


 * Transmetalation (alt. spelling: transmetallation): type of organometallic reaction that involves the transfer of ligands from one metal to another. It has the general form: M1–R + M2–R′ → M1–R′ + M2–R, where R and R′ can be, but are not limited to, an alkyl, aryl, alkynyl, allyl, halogen, or pseudohalogen group.

Physical organic chemistry

 * Category:Physical organic chemistry


 * Physical organic chemistry (coined by Louis Hammett in 1940): focuses on the relationship between chemical structures and reactivity, in particular, applying experimental tools of physical chemistry to the study of organic molecules. Specific focal points of study include the rates of organic reactions, the relative chemical stabilities of the starting materials, reactive intermediates, transition states, and products of chemical reactions, and non-covalent aspects of solvation and molecular interactions that influence chemical reactivity. Such studies provide theoretical and practical frameworks to understand how changes in structure in solution or solid-state contexts impact reaction mechanism and rate for each organic reaction of interest. Chemical structure and thermodynamics: Thermochemistry, Conformational analysis, Non-covalent interactions, Acid–base chemistry. Chemical kinetics: Rate laws, Catalysis, Kinetic isotope effect, Substituent effects, Solvent effects. Quantum chemistry. Spectroscopy, spectrometry, and crystallography: NMR and EPR spectroscopy; Vibrational spectroscopy; Electronic excitation spectroscopy (UV-Vis spectroscopy): OHOM ↔ LUMO; Mass spectrometry; Crystallography


 * Woodward–Hoffmann rules (pericyclic selection rules): rationalize or predict certain aspects of the stereochemistry and activation energy of pericyclic reactions, an important class of reactions in organic chemistry. The rules are best understood in terms of the concept of the conservation of orbital symmetry using orbital correlation diagrams. The Woodward–Hoffmann rules are a consequence of the changes in electronic structure that occur during a pericyclic reaction and are predicated on the phasing of the interacting molecular orbitals. They are applicable to all classes of pericyclic reactions (and their microscopic reverse 'retro' processes), including (1) electrocyclizations, (2) cycloadditions, (3) sigmatropic reactions, (4) group transfer reactions, (5) ene reactions, (6) cheletropic reactions, and (7) dyotropic reactions. Due to their elegance, simplicity, and generality, the Woodward–Hoffmann rules are credited with first exemplifying the power of molecular orbital theory to experimental chemists.

Alcohols

 * Category:Alcohols
 * Category:Polyols
 * Category:Inositol


 * Polyol: organic compound containing multiple hydroxyl groups. The term "polyol" can have slightly different meanings depending on whether it is being used in the field of food science or that of polymer chemistry. A molecule with more than two hydroxyl groups is a polyol, with three – a triol, and with four – a tetrol. By convention, polyols do not refer to compounds that contain other functional groups.


 * Inositol:
 * myo-inositol: carbocyclic sugar that is abundant in brain and other mammalian tissues; it mediates cell signal transduction in response to a variety of hormones, neurotransmitters, and growth factors and participates in osmoregulation. It is a sugar alcohol with half the sweetness of sucrose (table sugar). It is made naturally in humans from glucose. A human kidney makes about two grams per day. Other tissues synthesize it too, and the highest concentration is in the brain, where it plays an important role by making other neurotransmitters and some steroid hormones bind to their receptors.
 * Isomers and structure: myo-inositol (meso compound, and hence optically inactive, because it has a plane of symmetry; assumes the chair conformation), scyllo-inositol, muco-inositol, 1D-chiro-Inositol and 1L-chiro-Inositol (the only pair of inositol enantiomers), neo-inositol, allo-Inositol, epi-Inositol, cis-Inositol.
 * Biosynthesis: Phytic acid (IP6) in plants - principal storage form of phosphorus in many plant tissues, especially bran and seed

Lipids, waxes, fatty acids, oils

 * Category:Lipids
 * Category:Waxes
 * Category:Fatty acids
 * Category:Oils

{q.v. User:Kazkaskazkasako/Work}


 * Oil: any nonpolar chemical substance that is a viscous liquid at ambient temperatures and is both hydrophobic (does not mix with water, literally "water fearing") and lipophilic (mixes with other oils, literally "fat loving"). Oils have a high carbon and hydrogen content and are usually flammable and surface active. Most oils are unsaturated lipids that are liquid at room temperature.


 * Template:Lipids


 * Template:Fatty acids


 * Fatty acid: carboxylic acid with a long aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have an unbranched chain of an even number of carbon atoms, from 4 to 28. Fatty acids are usually not found in organisms in their standalone form, but instead exist as three main classes of esters: triglycerides, phospholipids, and cholesteryl esters. In any of these forms, fatty acids are both important dietary sources of fuel for animals and they are important structural components for cells.
 * Types of fatty acids: Short-chain fatty acids (SCFA) are fatty acids with aliphatic tails of five or fewer carbons (e.g. butyric acid); Medium-chain fatty acids (MCFA) are fatty acids with aliphatic tails of 6 to 12 carbons, which can form medium-chain triglycerides; Long-chain fatty acids (LCFA) are fatty acids with aliphatic tails of 13 to 21 carbons; Very long chain fatty acids (VLCFA) are fatty acids with aliphatic tails of 22 or more carbons. Saturated fatty acids; Unsaturated fatty acids: cis, trans. Even- vs odd-chained fatty acids.
 * Nomenclature: Naming of fatty acids: Trivial names (or common names) are non-systematic historical names, which are the most frequent naming system used in literature; Systematic names (IUPAC names); Δx (delta-x): nomenclature, each double bond is indicated by Δx, where the double bond begins at the xth carbon–carbon bond, counting from carboxylic end of the molecule backbone. Each double bond is preceded by a cis- or trans- prefix; n−x (n minus x; also ω−x or omega-x) nomenclature both provides names for individual compounds and classifies them by their likely biosynthetic properties in animals. A double bond is located on the xth carbon–carbon bond, counting from the methyl end of the molecule backbone; Lipid numbers take the form C:D, where C is the number of carbon atoms in the fatty acid and D is the number of double bonds in the fatty acid. If D is more than one, the double bonds are assumed to be interrupted by CH2 units, i.e., at intervals of 3 carbon atoms along the chain.


 * List of saturated fatty acids


 * Fatty amine (lipid amine?): any amine attached to a hydrocarbon chain of eight or more carbon atoms in length. These compounds are classified as oleochemicals. More commonly fatty amines are derived from C12-C18 hydrocarbons, which in turn are derived from the more abundant fatty acids. They are often mixtures. Commercially important members include coco amine, oleylamine, tallow amine, and soya amine. Some applications of these compounds are in fabric softeners, froth flotation agents (purification of ores), and corrosion inhibitors. They are the basis for a variety of cosmetic formulations.

Cyclic and aromatic compounds

 * Category:Cyclic compounds
 * Aromaticity


 * Aromaticity: chemical property of cyclic (ring-shaped), typically planar (flat) molecular structures with pi bonds in resonance (those containing delocalized electrons) that gives increased stability compared to saturated compounds having single bonds, and other geometric or connective non-cyclic arrangements with the same set of atoms. Aromatic rings are very stable and do not break apart easily. Organic compounds that are not aromatic are classified as aliphatic compounds—they might be cyclic, but only aromatic rings have enhanced stability. In terms of the electronic nature of the molecule, aromaticity describes a conjugated system often represented in Lewis diagrams as alternating single and double bonds in a ring. In reality, the electrons represented by the double bonds in the Lewis diagram are actually distributed evenly around the ring ("delocalized"), increasing the molecule's stability. Due to the restrictions imposed by the way Lewis diagrams are drawn, the molecule cannot be represented by one diagram, but rather a hybrid of multiple different diagrams (called resonance), such as with the two resonance structures of benzene. These molecules cannot be found in either one of these representations, with the longer single bonds in one location and the shorter double bond in another. Rather, the molecule exhibits all equal bond lengths in between those of single and double bonds . Characteristics of aromatic systems:


 * A delocalized conjugated π system, most commonly an arrangement of alternating single and double bonds
 * Coplanar structure, with all the contributing atoms in the same plane
 * Contributing atoms arranged in one or more rings
 * A number of π delocalized electrons that is even, but not a multiple of 4. That is, $$4n+2$$ π-electrons, where $$n=0,1,2,3,...$$. This is known as Hückel's rule.

Nitrogen compounds

 * Template:Nitrogen compounds
 * Hydrides
 * Organic
 * Oxides
 * Halides
 * Oxidation states


 * Nitrous oxide (N₂O, laughing gas): colourless non-flammable gas, and has a slightly sweet scent and taste. At elevated temperatures, nitrous oxide is a powerful oxidiser similar to molecular oxygen. Nitrous oxide has significant medical uses, especially in surgery and dentistry, for its anaesthetic and pain-reducing effects. "Laughing gas" due to the euphoric effects upon inhaling it, a property that has led to its recreational use as a dissociative anaesthetic. It is on the World Health Organization's List of Essential Medicines. It is also used as an oxidiser in rocket propellants, and in motor racing to increase the power output of engines. Nitrous oxide is used as a propellant, and has a variety of applications from rocketry to making whipped cream.


 * NOx : shorthand for nitric oxide (NO) and nitrogen dioxide (NO₂), the nitrogen oxides that are most relevant for air pollution. These gases contribute to the formation of smog and acid rain, as well as affecting tropospheric ozone. gases are usually produced from the reaction between nitrogen and oxygen during combustion of fuels, such as hydrocarbons, in air; especially at high temperatures, such as in car engines.  does not include nitrous oxide (N₂O).  is defined as the sum of  plus the  compounds produced from the oxidation of  which include nitric acid, nitrous acid (HONO), dinitrogen pentoxide (N₂O₅), peroxyacetyl nitrate (PAN), alkyl nitrates (RONO₂), peroxyalkyl nitrates (ROONO₂), the nitrate radical (NO₃), and peroxynitric acid (HNO₄).
 * Peroxyacetyl nitrate (PAN): secondary pollutant present in photochemical smog. It is thermally unstable and decomposes into peroxyethanoyl radicals and nitrogen dioxide gas; lachrymatory substance.


 * Diimide (diazene, diimine): HN=NH. It exists as two geometric isomers, E (trans) and Z (cis). The term diazene is more common for organic derivatives of diimide.


 * Hydrazoic acid (hydrogen azide, azoimide): HN₃, colorless, volatile, and explosive liquid at room temperature and pressure. The acid has few applications, but its conjugate base, the azide ion, is useful in specialized processes. Hydrazoic acid, like its fellow mineral acids, is soluble in water. Undiluted hydrazoic acid is dangerously explosive. When dilute, the gas and aqueous solutions (<10%) can be safely prepared but should be used immediately; because of its low boiling point, hydrazoic acid is enriched upon evaporation and condensation such that dilute solutions incapable of explosion can form droplets in the headspace of the container or reactor that are capable of explosion.
 * Azide: linear, polyatomic anion with the formula N3- and structure ⁻N=N⁺=N⁻. Organic azides are organic compounds with the formula RN₃, containing the azide functional group. The dominant application of azides is as a propellant in air bags.


 * Triazene: unsaturated inorganic compound having the chemical formula N₃H₃. It has one double bond and is the second-simplest member of the azene class of hydronitrogen compounds, after diimide. Triazenes are a class of organic compounds containing the functional group -N(H)-N=N-.


 * Hydroxylamine (Hydroxyammonia): inorganic compound with the formula NH₂OH. Hydroxylamine is almost always provided and used as an aqueous solution.

Silicon (Si) compounds

 * Category:Silicon compounds
 * Category:Organosilicon compounds
 * Category:Siloxanes
 * Category:Silicones


 * Silicone oil: any liquid polymerized siloxane with organic side chains. The most important member is polydimethylsiloxane. These polymers are of commercial interest because of their relatively high thermal stability and their lubricating properties.
 * Polydimethylsiloxane (PDMS): silicone polymer with a wide variety of uses, from cosmetics to industrial lubrication. It is particularly known for its unusual rheological (or flow) properties. PDMS is optically clear and, in general, inert, non-toxic, and non-flammable. It is one of several types of silicone oil (polymerized siloxane).
 * Hexamethyldisiloxane (HMDSO)


 * Trimethylsilyl chloride (TMSCl; Me₃SiCl): colourless volatile liquid that is stable in the absence of water. It is widely used in organic chemistry.

Inorganic chemistry

 * Category:Inorganic chemistry
 * Category:Bioinorganic chemistry
 * Category:Organometallic chemistry


 * Amalgam (chemistry): substance formed by the reaction of mercury (Hg) with another metal. Almost all metals can form amalgams with mercury, the notable exception being iron (Fe). Silver-mercury (Ag-Hg) amalgams are important in dentistry, and gold-mercury (Au-Hg) amalgam is used in the extraction of gold from ore.


 * Antimonate: compound which contains a metallic element, oxygen, and antimony in an oxidation state of +5. These compounds adopt polymeric structures with M-O-Sb linkages. They can be considered to be derivatives of the hypothetical antimonic acid H₃SbO₄, or combinations of metal oxides and antimony pentoxide, Sb₂O₅.

Organometallic chemistry, coordination compounds

 * Category:Coordination complexes
 * Category:Cyclopentadienyl complexes
 * Category:Organometallic chemistry
 * Category:Cyclopentadienyl complexes
 * Category:Sandwich compounds
 * Category:Metallocenes
 * Category:Ferrocenes


 * Ferrocene: organometallic compound with the formula Fe(C5H5)2. Molecule consists of two cyclopentadienyl rings bound on opposite sides of a central iron atom. It is an orange solid with a camphor-like odor, that sublimes above room temperature, and is soluble in most organic solvents. It is remarkable for its stability: it is unaffected by air, water, strong bases, and can be heated to 400°C without decomposition. In oxidizing conditions it can reversibly react with strong acids to form the ferrocenium cation Fe(C5H5)2(+).


 * Hapticity: coordination of a ligand to a metal center via an uninterrupted and contiguous series of atoms. The hapticity of a ligand is described with the Greek letter η ('eta'). η2 describes a ligand that coordinates through 2 contiguous atoms. Ferrocene contains two η5-cyclopentadienyl ligands (bis(η5-cyclopentadienyl)iron).


 * Transition metal alkene complex: coordination compound containing one or more alkene ligands. Such compounds are intermediates in many catalytic reactions that convert alkenes to other organic products. Zeise's salt (K [ PtCl3(C2H4)]·H2O). Dewar–Chatt–Duncanson model.

Chemical engineering

 * Category:Chemical engineering {q.v. User:Kazkaskazkasako/Work}
 * Category:Particle technology


 * Outline of chemical engineering


 * Chemical engineering: branch of engineering that applies physical sciences (physics and chemistry) and life sciences (microbiology and biochemistry) together with applied mathematics and economics to produce, transform, transport, and properly use chemicals, materials and energy. Ehemical engineers design large-scale processes that convert chemicals, raw materials, living cells, microorganisms and energy into useful forms and products.


 * Transport phenomena: concerns the exchange of mass, energy, charge, momentum and angular momentum between observed and studied systems. Mass, momentum, and heat transport all share a very similar mathematical framework, and the parallels between them are exploited in the study of transport phenomena to draw deep mathematical connections that often provide very useful tools in the analysis of one field that are directly derived from the others. The fundamental analyses in all three subfields of mass, heat, and momentum transfer are often grounded in the simple principle that the sum total of the quantities being studied must be conserved by the system and its environment. Transport phenomena encompass all agents of physical change in the universe. Moreover, they are considered to be fundamental building blocks which developed the universe, and which is responsible for the success of all life on earth. In physics, transport phenomena are all irreversible processes of statistical nature stemming from the random continuous motion of molecules, mostly observed in fluids. Every aspect of transport phenomena is grounded in two primary concepts : the conservation laws, and the constitutive equations.
 * Mass transfer: net movement of mass from one location, usually meaning stream, phase, fraction or component, to another. Mass transfer occurs in many processes, such as absorption, evaporation, drying, precipitation, membrane filtration, and distillation. The phrase is commonly used in engineering for physical processes that involve diffusive and convective transport of chemical species within physical systems.
 * Mass transfer coefficient: diffusion rate constant that relates the mass transfer rate, mass transfer area, and concentration change as driving force

$$k_c = \frac{\dot{n}_A}{A \Delta c_A}$$ where
 * $$k_c$$ is the mass transfer coefficient [mol/(s&middot;m2)/(mol/m3)], or m/s
 * $$\dot{n}_A$$'' is the mass transfer rate [mol/s]
 * $$A$$ is the effective mass transfer area [m2]
 * $$\Delta c_A$$ is the driving force concentration difference [mol/m3]
 * Chilton and Colburn J-factor analogy: successful and widely used analogy between heat, momentum, and mass transfer.


 * Scale (chemistry) of a chemical process: rough ranges in mass or volume of a chemical reaction or process that define the appropriate category of chemical apparatus and equipment required to accomplish it, and the concepts, priorities, and economies that operate at each. Laboratory scale. Bench scale sets of procedures, 10- to 200-fold larger than the discovery laboratory. Pilot plant scale, e.g., carried out by process chemists, which, though at the lowest extreme of manufacturing operations, are on the order of 200- to 1000-fold larger than laboratory scale. Demonstration scale and full-scale production.

Particle technology

 * Category:Particle technology
 * Category:Granularity of materials


 * Particle technology: "science and technology related to the handling and processing of particles and powders." This applies to the production, handling, modification, and use of a wide variety of particulate materials, both wet or dry, in sizes ranging from nanometers to centimeters; its scope spans a range of industries to include chemical, petrochemical, agricultural, food, pharmaceuticals, mineral processing, civil engineering, advanced materials, energy, and the environment. Subjects of particle technology:
 * behavior of solids in bulk, including soil mechanics, bulk material handling, silos, conveying, powder metallurgy, nanotechnology
 * size reduction including crushing and grinding
 * increasing size by flocculation, granulation, powder compaction, tableting, crystallization
 * particle separation, such as sieving, tabling, flotation, magnetic separation, and/or electrostatic precipitation, fluidization, Centrifugal separation, Liquid filtration
 * analytical procedures such as particle size analysis


 * Random close pack (RCP): empirical parameter used to characterize the maximum volume fraction of solid objects obtained when they are packed randomly. For example, when a solid container is filled with grain, shaking the container will reduce the volume taken up by the objects, thus allowing more grain to be added to the container. In other words, shaking increases the density of packed objects. But shaking cannot increase the density indefinitely, a limit is reached, and if this is reached without obvious packing into a regular crystal lattice, this is the empirical random close-packed density. Experiments and computer simulations have shown that the most compact way to pack hard perfect spheres randomly gives a maximum volume fraction of about 64%, i.e., approximately 64% of the volume of a container is occupied by the spheres. It seems as if because it is not possible to precisely define 'random' in this sense it is not possible to give an exact value. The random close packing value is significantly below the maximum possible close-packing of (equal sized) hard spheres into a regular crystalline arrangements, which is 74.04% -- both the face-centred cubic (fcc) and hexagonal close packed (hcp) crystal lattices have maximum densities equal to this upper limit.

Analytical chemistry

 * Category:Analytical chemistry
 * Category:Chromatography
 * Category:Gas chromatography (AKA gas-liquid chromatography, gas-liquid partition chromatography)
 * Liquid chromatography (AKA chromatography): HPLC, UHPLC; analytical scale, narrow-bore, capillary columns
 * Category:Electroanalytical chemistry
 * Category:Electroanalytical methods
 * Category:Electrophoresis
 * Category:Separation processes
 * Category:Filtration
 * Category:Filters
 * Category:Titration
 * Category:Chemical equipment
 * Category:Filters


 * Chromatography: laboratory technique for the separation of a mixture. Chromatography may be preparative or analytical.
 * The analyte is the substance to be separated during chromatography. It is also normally what is needed from the mixture.
 * Analytical chromatography is used to determine the existence and possibly also the concentration of analyte(s) in a sample.
 * A bonded phase is a stationary phase that is covalently bonded to the support particles or to the inside wall of the column tubing.
 * A chromatogram is the visual output of the chromatograph. In the case of an optimal separation, different peaks or patterns on the chromatogram correspond to different components of the separated mixture.
 * A chromatograph is equipment that enables a sophisticated separation, e.g. gas chromatographic or liquid chromatographic separation.
 * Chromatography is a physical method of separation that distributes components to separate between two phases, one stationary (stationary phase), the other (the mobile phase) moving in a definite direction.
 * The eluate is the mobile phase leaving the column. This is also called effluent.
 * The eluent is the solvent that carries the analyte.
 * The eluite is the analyte, the eluted solute.
 * An eluotropic series is a list of solvents ranked according to their eluting power.
 * An immobilized phase is a stationary phase that is immobilized on the support particles, or on the inner wall of the column tubing.
 * The mobile phase is the phase that moves in a definite direction. It may be a liquid (LC and Capillary Electrochromatography (CEC)), a gas (GC), or a supercritical fluid (supercritical-fluid chromatography, SFC). The mobile phase consists of the sample being separated/analyzed and the solvent that moves the sample through the column. In the case of HPLC the mobile phase consists of a non-polar solvent(s) such as hexane in normal phase or a polar solvent such as methanol in reverse phase chromatography and the sample being separated. The mobile phase moves through the chromatography column (the stationary phase) where the sample interacts with the stationary phase and is separated.
 * Preparative chromatography is used to purify sufficient quantities of a substance for further use, rather than analysis.
 * The retention time is the characteristic time it takes for a particular analyte to pass through the system (from the column inlet to the detector) under set conditions.
 * The sample is the matter analyzed in chromatography. It may consist of a single component or it may be a mixture of components. When the sample is treated in the course of an analysis, the phase or the phases containing the analytes of interest is/are referred to as the sample whereas everything out of interest separated from the sample before or in the course of the analysis is referred to as waste.
 * The solute refers to the sample components in partition chromatography.
 * The solvent refers to any substance capable of solubilizing another substance, and especially the liquid mobile phase in liquid chromatography.
 * The stationary phase is the substance fixed in place for the chromatography procedure.
 * The detector refers to the instrument used for qualitative and quantitative detection of analytes after separation.

Chromatography is based on the concept of partition coefficient. Any solute partitions between two immiscible solvents. When we make one solvent immobile (by adsorption on a solid support matrix) and another mobile it results in most common applications of chromatography. If the matrix support, or stationary phase, is polar (e.g. paper, silica etc.) it is forward phase chromatography, and if it is non-polar (C-18) it is reverse phase.


 * Theoretical plate: in many separation processes is a hypothetical zone or stage in which two phases, such as the liquid and vapor phases of a substance, establish an equilibrium with each other. Such equilibrium stages may also be referred to as an equilibrium stage, ideal stage, or a theoretical tray. In other words, having more theoretical plates increases the efficiency of the separation process be it either a distillation, absorption, chromatographic, adsorption or similar process. The theoretical plate concept was also adapted for chromatographic processes by Martin and Synge. The IUPAC's Gold Book provides a definition of the number of theoretical plates in a chromatography column.


 * High-performance liquid chromatography:
 * active component of the column, the adsorbent, is typically a granular material made of solid particles (e.g. silica, polymers, ...), 2–50 μm in size
 * "mobile phase": pressurized liquid, typically a mixture of solvents (e.g. water, acetonitrile and/or methanol). _composition and temperature_ play a major role in the separation process by influencing the interactions taking place between sample components and adsorbent. Physical interactions: hydrophobic (dispersive), dipole–dipole and ionic, most often a combination
 * schematic of an HPLC instrument: "degasser", "sampler", "pumps", and a "detector"
 * Types:
 * Partition chromatography
 * Normal–phase chromatography
 * Displacement chromatography
 * Reversed-phase chromatography (RPC)
 * Size-exclusion chromatography
 * Ion-exchange chromatography
 * Bioaffinity chromatography
 * Aqueous normal-phase chromatography.

Parameters: Theoretical, Internal diameter, Particle size, Pore size, Pump pressure, Detectors, Autosamplers. Internal diameter (ID) of an HPLC column is an important parameter that influences the detection sensitivity and separation selectivity in gradient elution. It also determines the quantity of analyte that can be loaded onto the column. Larger columns are usually seen in industrial applications, such as the purification of a drug product for later use. Low-ID columns have improved sensitivity and lower solvent consumption at the expense of loading capacity. HPLC pressure may reach as high as 60 MPa, or about 600 atmospheres. Modern HPLC systems have been improved to work at much higher pressures, and therefore are able to use much smaller particle sizes in the columns (<2 μm). These "ultra high performance liquid chromatography systems" or UHPLCs can work at up to 120 MPa, or about 1200 atmospheres.
 * Analytical scale columns (4.6 mm) have been the most common type of columns, though smaller columns are rapidly gaining in popularity. They are used in traditional quantitative analysis of samples and often use a UV-Vis absorbance detector.
 * Narrow-bore columns (1–2 mm) are used for applications when more sensitivity is desired either with special UV-vis detectors, fluorescence detection or with other detection methods like liquid chromatography-mass spectrometry
 * Capillary columns (under 0.3 mm) are used almost exclusively with alternative detection means such as mass spectrometry. They are usually made from fused silica capillaries, rather than the stainless steel tubing that larger columns employ.
 * Monolithic HPLC column: column used in HPLC. The internal structure of the monolithic column is created in such a way that many channels form inside the column. The material inside the column which separates the channels can be porous and functionalized. In contrast, most HPLC configurations use particulate packed columns; in these configurations, tiny beads of an inert substance, typically a modified silica, are used inside the column.
 * Aqueous normal-phase chromatography (ANP): chromatographic technique that involves the mobile phase region between reversed-phase chromatography (RP) and organic normal-phase chromatography (ONP). In normal-phase chromatography, the stationary phase is polar and the mobile phase is nonpolar. In reversed phase we have just the opposite; the stationary phase is nonpolar and the mobile phase is polar. Typical stationary phases for normal-phase chromatography are silica or organic moieties with cyano and amino functional groups. For reversed phase, alkyl hydrocarbons are the preferred stationary phase; octadecyl (C18) is the most common stationary phase, but octyl (C8) and butyl (C4) are also used in some applications. The designations for the reversed phase materials refer to the length of the hydrocarbon chain. Typically the amount of the nonpolar component in the mobile phase must be 60% or greater with the exact point of increased retention depending on the solute and the organic component of the mobile phase. A true ANP stationary phase will be able to function in both the reversed phase and normal phase modes with only the amount of water in the eluent varying. Thus a continuum of solvents can be used from 100% aqueous to pure organic.
 * Liquid chromatography–mass spectrometry: analytical chemistry technique that combines the physical separation capabilities of liquid chromatography (or HPLC) with the mass analysis capabilities of mass spectrometry (MS). Coupled chromatography - MS systems are popular in chemical analysis because the individual capabilities of each technique are enhanced synergistically. While liquid chromatography separates mixtures with multiple components, mass spectrometry provides structural identity of the individual components with high molecular specificity and detection sensitivity. This tandem technique can be used to analyze biochemical, organic, and inorganic compounds commonly found in complex samples of environmental and biological origin. LC-MS system contains an interface that efficiently transfers the separated components from the LC column into the MS ion source. The interface is necessary because the LC and MS devices are fundamentally incompatible. While the mobile phase in a LC system is a pressurized liquid, the MS analyzers commonly operate under vacuum. Thus, it is not possible to directly pump the eluate from the LC column into the MS source. Overall, the interface is a mechanically simple part of the LC-MS system that transfers the maximum amount of analyte, removes a significant portion of the mobile phase used in LC and preserves the chemical identity of the chromatography products (chemically inert). Nowadays, most extensively applied LC-MS interfaces are based on atmospheric pressure ionization (API) strategies like electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI), and atmospheric pressure photo-ionization (APPI).
 * Solid-phase extraction (SPE): extractive technique by which compounds that are dissolved or suspended in a liquid mixture are separated from other compounds in the mixture according to their physical and chemical properties. Analytical laboratories use solid phase extraction to concentrate and purify samples for analysis. SPE uses the affinity of solutes dissolved or suspended in a liquid (known as the mobile phase) for a solid through which the sample is passed (known as the stationary phase) to separate a mixture into desired and undesired components. The result is that either the desired analytes of interest or undesired impurities in the sample are retained on the stationary phase. SPE and chromatography. Normal phase SPE procedure. Reversed phase SPE. Ion exchange SPE (Anion, Cation). Cartridges. Solid-phase microextraction.


 * Gas chromatography (GC, gas-liquid chromatography (GLC), vapor-phase chromatography (VPC), gas–liquid partition chromatography (GLPC)): common type of chromatography used in analytical chemistry for separating and analyzing compounds that can be vaporized without decomposition. Typical uses of GC include testing the purity of a particular substance, or separating the different components of a mixture (the relative amounts of such components can also be determined). In some situations, GC may help in identifying a compound. In preparative chromatography, GC can be used to prepare pure compounds from a mixture. In gas chromatography, the mobile phase (or "moving phase") is a carrier gas, usually an inert gas such as helium or an unreactive gas such as nitrogen. Helium remains the most commonly used carrier gas in about 90% of instruments although hydrogen is preferred for improved separations. The stationary phase is a microscopic layer of liquid or polymer on an inert solid support, inside a piece of glass or metal tubing called a column (an homage to the fractionating column used in distillation). Gas chromatography is in principle similar to column chromatography (as well as other forms of chromatography, such as HPLC, TLC), but has several notable differences. First, the process of separating the compounds in a mixture is carried out between a liquid stationary phase and a gas mobile phase, whereas in column chromatography the stationary phase is a solid and the mobile phase is a liquid. (Hence the full name of the procedure is "Gas–liquid chromatography", referring to the mobile and stationary phases, respectively.) Second, the column through which the gas phase passes is located in an oven where the temperature of the gas can be controlled, whereas column chromatography (typically) has no such temperature control. Finally, the concentration of a compound in the gas phase is solely a function of the vapor pressure of the gas. Gas chromatography is also similar to fractional distillation, since both processes separate the components of a mixture primarily based on boiling point (or vapor pressure) differences. However, fractional distillation is typically used to separate components of a mixture on a large scale, whereas GC can be used on a much smaller scale (i.e. microscale).


 * Elution: process of extracting one material from another by washing with a solvent; as in washing of loaded ion-exchange resins to remove captured ions. Eluotropic series is listing of various compounds in order of eluting power for a given adsorbent. The “eluting power” of a solvent is largely a measure of how well the solvent can "pull" an analyte off the adsorbent to which it is attached. The order of solvents in an eluotropic series depends both on the stationary phase as well as on the compound used to determine the order.


 * Retardation factor (R): fraction of an analyte in the mobile phase of a chromatographic system. Although the term retention factor is sometimes used synonymously with retardation factor in regard to planar chromatography the term is not defined in this context. However, in column chromatography, the retention factor or capacity factor (k) is defined as the ratio of time an analyte is retained in the stationary phase to the time it is retained in the mobile phase, which is inversely proportional to the retardation factor.


 * Full width at half maximum (FWHM): expression of the extent of function given by the difference between the two extreme values of the independent variable at which the dependent variable is equal to half of its maximum value. Half width at half maximum (HWHM) is half of the FWHM.

Titration:
 * Kjeldahl method (Danish pronunciation: [ˈkʰelˌtɛˀl]): method for the quantitative determination of nitrogen contained in organic substances plus the nitrogen contained in the inorganic compounds ammonia and ammonium (NH₃/NH₄⁺). Without modification, other forms of inorganic nitrogen, for instance nitrate, are not included in this measurement. Using an empirical relation between Kjeldahl nitrogen content and protein content it is an important method for analyzing proteins. This method was developed by Johan Kjeldahl in 1883. Method: The method consists of heating a sample to 360–410 °C with concentrated sulfuric acid (H₂SO₄), which decomposes ("digests" or "destructs") the organic sample by oxidation to liberate the reduced nitrogen as ammonium sulfate: C + 2 H₂SO₄ → CO₂ + 2 SO₂ + 2 H₂O; S + 2 H₂SO₄ → 3 SO₂ + 2 H₂O. Limitations: Kjeldahl method is not applicable to compounds containing nitrogen in nitro and azo groups and nitrogen present in rings (e.g. pyridine, quinoline, isoquinoline) as nitrogen of these compounds does not convert to ammonium sulfate under the conditions of this method.

stokes, centistokes
 * Viscosity: The SI unit of kinematic viscosity is m²/s, whereas the cgs unit for kinematic viscosity is the stokes (St), named after Sir George Gabriel Stokes. It is sometimes expressed in terms of centistokes (cSt). In U.S. usage, stoke is sometimes used as the singular form.


 * Dilatant: dilatant (also termed shear thickening) material is one in which viscosity increases with the rate of shear strain. Such a shear thickening fluid, also known by the initialism STF, is an example of a non-Newtonian fluid. This behaviour is usually not observed in pure materials, but can occur in suspensions.


 * Quechers (QuEChERS: "quick, easy, cheap, effective, rugged, and safe"): solid phase extraction method for detection of pesticide residues in food.
 * Accelerated solvent extraction (ASE): method for extracting various chemicals from a complex solid or semisolid sample matrix. The process uses high temperature and pressure, which results in the extraction taking less time and requiring less solvent, and possibly also giving better analyte recovery, than traditional methods that use less extreme conditions. The elevated temperature is employed to increase extraction efficiency of the analyte of interest and the elevated pressure is used to keep the solvent in a liquid state as the temperature is increased above its boiling point. An automated system for the process was developed by Dionex.
 * Soxhlet extractor: piece of laboratory apparatus invented in 1879 by Franz von Soxhlet. It was originally designed for the extraction of a lipid from a solid material. Typically, Soxhlet extraction is used when the desired compound has a limited solubility in a solvent, and the impurity is insoluble in that solvent.


 * Moisture analysis: variety of methods for measuring moisture content in both high level and trace amounts in solids, liquids, or gases. Moisture in percentage amounts is monitored as a specification in commercial food production. There are many applications where trace moisture measurements are necessary for manufacturing and process quality assurance. Trace moisture in solids must be controlled for plastics, pharmaceuticals and heat treatment processes.
 * Karl Fischer titration: classic titration method in analytical chemistry that uses coulometric or volumetric titration to determine trace amounts of water in a sample. It was invented in 1935 by the German chemist Karl Fischer. Today, the titration is done with an automated Karl Fischer titrator.
 * The popularity of the Karl Fischer titration (henceforth referred to as KF) is due in large part to several practical advantages that it holds over other methods of moisture determination, such as accuracy, speed and selectivity.
 * Little sample preparation is needed: a liquid sample can usually be directly injected using a syringe. The analysis is typically complete within a minute. However, KF suffers from an error called drift, which is an apparent water input that can confuse the measurement. The glass walls of the vessel adsorb water, and if any water leaks into the cell, the slow release of water into the titration solution can continue for a long time. Therefore, before measurement, it is necessary to carefully dry the vessel and run a 10-30 minute "dry run" in order to calculate the rate of drift. The drift is then subtracted from the result.


 * Depth filter: variety of filters that use a porous filtration medium to retain particles throughout the medium, rather than just on the surface of the medium. These filters are commonly used when the fluid to be filtered contains a high load of particles because, relative to other types of filters, they can retain a large mass of particles before becoming clogged.
 * Cross-flow filtration (tangential flow filtration (TFF)): majority of the feed flow travels tangentially across the surface of the filter, rather than into the filter. The principal advantage of this is that the filter cake (which can blind the filter) is substantially washed away during the filtration process, increasing the length of time that a filter unit can be operational. It can be a continuous process, unlike batch-wise dead-end filtration.
 * Nanofiltration: membrane filtration process used most often to soften and disinfect water. Uses nanometer sized pores through which particles smaller than 10 nanometers pass through the membrane. Nanofiltration membranes have pore sizes from 1-10 nanometers, smaller than that used in microfiltration and ultrafiltration, but a little bit bigger than that in reverse osmosis. Membranes used are predominantly created from polymer thin films. Advantages and disadvantages: One of the main advantages of nanofiltration as a method of softening water is that during the process of retaining calcium and magnesium ions while passing smaller hydrated monovalent ions, filtration is performed without adding extra sodium ions, as used in ion exchangers. Many separation processes do not operate at room temperature (e.g. distillation), which greatly increases the cost of the process when continuous heating or cooling is applied. Performing gentle molecular separation is linked with nanofiltration that is often not included with other forms of separation processes (centrifugation).


 * Salting out: effect based on the electrolyte-nonelectrolyte interaction, in which the non-electrolyte could be less soluble at high salt concentrations. It is used as method of separating proteins. The salt concentration needed for the protein to precipitate out of the solution differs from protein to protein. This process is also used to concentrate dilute solutions of proteins. Dialysis can be used to remove the salt if needed.


 * Capillary electrophoresis (CE): family of electrokinetic separation methods performed in submillimeter diameter capillaries and in micro- and nanofluidic channels. Very often, CE refers to capillary zone electrophoresis (CZE), but other electrophoretic techniques including capillary gel electrophoresis (CGE), capillary isoelectric focusing (CIEF), capillary isotachophoresis and micellar electrokinetic chromatography (MEKC) belong also to this class of methods. Electropherogram.

Chemistry software, cheminformatics

 * Category:Computational chemistry
 * Category:Computational chemistry software
 * Category:Molecular modelling software
 * Category:Cheminformatics
 * Category:Chemistry software
 * Category:Chemical file formats
 * Category:Crystallography software
 * Category:Molecular modelling
 * Category:Molecular modelling software

{q.v. }
 * User:Kazkaskazkasako/Work
 * User:Kazkaskazkasako/Work
 * User:Kazkaskazkasako/Books/EECS


 * International Chemical Identifier (InChI): textual identifier for chemical substances, designed to provide a standard way to encode molecular information and to facilitate the search for such information in databases and on the web. Initially developed by IUPAC (International Union of Pure and Applied Chemistry) and NIST (National Institute of Standards and Technology) from 2000 to 2005, the format and algorithms are non-proprietary. The identifiers describe chemical substances in terms of layers of information — the atoms and their bond connectivity, tautomeric information, isotope information, stereochemistry, and electronic charge information. Not all layers have to be provided; for instance, the tautomer layer can be omitted if that type of information is not relevant to the particular application. The InChI algorithm converts input structural information into a unique InChI identifier in a three-step process: normalization (to remove redundant information), canonicalization (to generate a unique number label for each atom), and serialization (to give a string of characters). InChIs differ from the widely used CAS registry numbers in three respects: firstly, they are freely usable and non-proprietary; secondly, they can be computed from structural information and do not have to be assigned by some organization; and thirdly, most of the information in an InChI is human readable (with practice). InChIs can thus be seen as akin to a general and extremely formalized version of IUPAC names. They can express more information than the simpler SMILES notation and differ in that every structure has a unique InChI string, which is important in database applications. Information about the 3-dimensional coordinates of atoms is not represented in InChI; for this purpose a format such as PDB can be used. The InChIKey, sometimes referred to as a hashed InChI, is a fixed length (27 character) condensed digital representation of the InChI that is not human-understandable. The InChIKey specification was released in September 2007 in order to facilitate web searches for chemical compounds, since these were problematic with the full-length InChI. Unlike the InChI, the InChIKey is not unique: though collisions can be calculated to be very rare, they happen.


 * CPK coloring (for Corey–Pauling–Koltun): popular color convention for distinguishing atoms of different chemical elements in molecular models. August Wilhelm von Hofmann was apparently the first to introduce molecular models into organic chemistry, following August Kekule's introduction of the theory of chemical structure in 1858, and Alexander Crum Brown's introduction of printed structural formulas in 1861. Hofmann's original colour scheme (carbon = black, hydrogen = white, nitrogen = blue, oxygen = red, chlorine = green, and sulphur = yellow) has evolved into the later color schemes. Modern variants: C is the original assignment by Corey and Pauling; K is that of Koltun's patent; J - Jmol; R - Rasmol; P - Pubchem (different colors for: H, C). Agreements: O - red, N - blue, S - yellow, Cl - green, Au - dark yellow/brownish,


 * Chemical file format: Distinguishing formats:
 * file extension (usually 3 letters). This is widely used, but fragile as common suffixes such as ".mol" and ".dat" are used by many systems, including non-chemical ones
 * self-describing files where the format information is included in the file, e.g. CIF, CML
 * chemical/MIME type added by a chemically-aware server
 * Chemical Markup Language (CML): open source project includes XML Schema, source code for parsing and working with CML data, and an active community.
 * Protein Data Bank Format.
 * GROMACS format.
 * CHARMM format.
 * GSD format.
 * Ghemical file format.
 * SYBYL Line Notation (SLN): based on SMILES, it incorporates a complete syntax for specifying relative stereochemistry.
 * Simplified molecular-input line-entry system (SMILES): specification in the form of a line notation for describing the structure of chemical species using short ASCII strings. SMILES strings can be imported by most molecule editors for conversion back into two-dimensional drawings or three-dimensional models of the molecules. The original SMILES specification was initiated in the 1980s. It has since been modified and extended. In 2007, an open standard called OpenSMILES was developed in the open-source chemistry community. SMILES strings include connectivity but do not include 2D or 3D coordinates.
 * XYZ.
 * MDL number: unique identification number for each reaction and variation. The format is RXXXnnnnnnnn. R indicates a reaction, XXX indicates which database contains the reaction record. The numeric portion, nnnnnnnn, is an 8-digit number.
 * Converting between formats: OpenBabel and JOELib.
 * Crystallographic Information File (CIF): standard text file format for representing crystallographic information, promulgated by IUCr
 * Macromolecular Crystallographic Information File (mmCIF): standard text file format for representing macromolecular structure data, developed by IUCr and Protein Data Bank. It is an extension of CIF, specifically for macromolecular data, such as proteins and nucleic acids, incorporating elements from the PDB file format. mmCIF is intended as an alternative to the Protein Data Bank (PDB) format and is now the default format used by the Protein Data Bank.
 * Protein Data Bank (file format) (.pdb): textual file format describing the three-dimensional structures of molecules held in the Protein Data Bank, now succeeded by the mmCIF format. The PDB format accordingly provides for description and annotation of protein and nucleic acid structures including atomic coordinates, secondary structure assignments, as well as atomic connectivity. In addition experimental metadata are stored. The PDB format is the legacy file format for the Protein Data Bank which now keeps data on biological macromolecules in the newer mmCIF file format.
 * Chemical table file: family of text-based chemical file formats that describe molecules and chemical reactions. One format, for example, lists each atom in a molecule, the x-y-z coordinates of that atom, and the bonds among the atoms. File formats: Molfile (MDL Molfile), Extended Connection Table (V3000).


 * SMILES.png


 * Template:Chemistry software (Computational chemistry software):
 * Cheminformatics: Canvas (Schrödinger); Open Babel; CDK (Java); RDKit
 * Chemical kinetics
 * Molecular modelling and visualization: Avogadro; PyMOL (Schrödinger); UCSF Chimera; ChemDraw; Marvin; RasMol; VMD
 * Molecular docking
 * Molecular dynamics
 * Quantum chemistry
 * Skeletal structure drawing
 * Others
 * List of cheminformatics toolkits: List of notable cheminformatics toolkits: 3D-e-Chem, CDD Vault, CDK, ChemmineR, Enalos KNIME nodes, Enalos+ KNIME nodes, Molecular Operating Environment (MOE), Open Babel, Rcpi, RDKit, SMSD


 * Molecule editor: computer program for creating and modifying representations of chemical structures. Molecule editors can manipulate chemical structure representations in either a simulated two-dimensional space or three-dimensional space, via 2D computer graphics or 3D computer graphics, respectively. Two-dimensional output is used as illustrations or to query chemical databases. Three-dimensional output is used to build molecular models, usually as part of molecular modelling software packages.
 * Standalone programs: Amira (Thermo Fisher Scientific), Avogadro, ChemDraw


 * List of molecular graphics systems: Amira; Avogadro; PyMOL; RasMol; UCSF Chimera.
 * Molecular design software: polymers, peptides, nucleic acids, solvents, partial charges, docking, optimization, molecular mechanics, quantum mechanics, Force Fields. Software: Abalone, Discovery Studio, HyperChem with HMHC and DSHC, Maestro (Schrödinger), MAPS, Molecular Operating Environment (MOE), SAMSON, Scigress, Spartan.


 * Structural alignment software: structure-function
 * List of sequence alignment software
 * Biopython


 * Software Tools For Molecular Microscopy: molecular microscopy or cryo-electron microscopy (cryoEM)


 * Open Babel: chemical expert system mainly used to interconvert chemical file formats. Due to the strong relationship to informatics this program belongs more to the category cheminformatics than to molecular modelling. The project's stated goal is: "Open Babel is a community-driven scientific project assisting both users and developers as a cross-platform program and library designed to support molecular modeling, chemistry, and many related areas, including interconversion of file formats and data."
 * Chemistry Development Kit (CDK (Java); Windows, Linux, Unix, macOS): computer software, a library in Java, for chemoinformatics and bioinformatics. Cinfony: Python wrapper.


 * PyMOL: open source molecular visualization system created by Warren Lyford DeLano; currently commercialized by Schrödinger, Inc. PyMOL can produce high-quality 3D images of small molecules and biological macromolecules, such as proteins. PyMOL used Tk for the GUI widgets and had native Aqua binaries for macOS through Schrödinger, which were replaced with a PyQt user interface on all platforms with the release of version 2.0. 2010.01.08 Schrödinger, Inc. reached an agreement to acquire PyMOL. The firm assumed development, maintenance, support, and sales of PyMOL, including all then-valid subscriptions. They also continue to actively support the PyMOL open-source community. In 2017, Schrödinger revamped the distribution system to unify the user interface under Qt and the package management under Anaconda, and released it as PyMol v2.
 * Schrödinger, Inc.: life sciences and materials science company founded in 1990 that develops software for computational chemistry and has a pipeline of collaborative and internal drug discovery programs. The company is headquartered in New York, with regional headquarters in Munich, Tokyo and Bangalore.
 * Avogadro (software): molecule editor and visualizer designed for cross-platform use in computational chemistry, molecular modeling, bioinformatics, materials science, and related areas. It is extensible via a plugin architecture.
 * UCSF Chimera
 * ChemDraw (Win, macOS): molecule editor first developed in 1985 by David A. Evans and Stewart Rubenstein (later by the cheminformatics company CambridgeSoft). The company was sold to PerkinElmer in the year 2011. ChemDraw, along with Chem3D and ChemFinder, is part of the ChemOffice suite of programs. ChemDraw 12.0: Chemical structure to name conversion; Chemical name to structure conversion; NMR spectrum simulation (1H and 13C); Mass spectrum simulation
 * ChemAxon: cheminformatics and bioinformatics software development company specializing in cloud based, end user solutions, back end platforms and consultancy services for chemical and biological research. ChemAxon provides solutions, platforms, applications, and consultancy services for handling chemical and biological entities for the pharmaceutical, biotechnology, new materials, fine-, petro- and agrochemical, food and cosmetics industries. JChem: a desktop application for end user scientists; JChem for Excel integrates the structure handling capabilities of JChem and Marvin within a Microsoft Excel environment. Marvin: free chemistry software for drawing and visualizing chemical structures (MarvinSketch, MarvinView).
 * Chemicalize: online platform for chemical calculations, search, and text processing. Modules of Chemicalize: Calculations, Chemical Search, Compliance Checker.
 * Amira (software): software platform for 3D and 4D data visualization, processing, and analysis. It is being actively developed by Thermo Fisher Scientific in collaboration with the Zuse Institute Berlin (ZIB), and commercially distributed by Thermo Fisher Scientific. Extendable software system for scientific visualization, data analysis, and presentation of 3D and 4D data. Its flexible user interface and modular architecture make it a universal tool for processing and analysis of data from various modalities; e.g. micro-CT, PET, Ultrasound, ..., microscopy in biology and materials science, molecular biology, quantum physics, astrophysics, computational fluid dynamics (CFD), finite element modeling (FEM), non-destructive testing (NDT). One of the key features, besides data visualization, is Amira’s set of tools for image segmentation and geometry reconstruction. Amira options: Microscopy option, DICOM reader, Mesh option, Skeletonization option, Molecular option, Developer option, Neuro option, VR option, Very large data option.


 * ChEMBL (ChEMBLdb): manually curated chemical database of bioactive molecules with drug-like properties. It is maintained by EBI, of EMBL, based at the Wellcome Trust Genome Campus, Hinxton, UK. Associated resources: In 2013.12, the operations of the SureChem patent informatics database were transferred to EMBL-EBI. In a portmanteau, SureChem was renamed SureChEMBL.


 * ChemSpider: database of chemicals. ChemSpider is owned by the Royal Society of Chemistry.


 * Spectral Database for Organic Compounds (SDBS): free online searchable database hosted by the National Institute of Advanced Industrial Science and Technology (AIST) in Japan, that contains spectral data for ca 34,000 organic molecules. The database is available in English and in Japanese and it includes six types of spectra: laser Raman spectra, electron ionization mass spectra (EI-MS), Fourier-transform infrared (FT-IR) spectra, 1H nuclear magnetic resonance (¹H-NMR) spectra, ¹³C nuclear magnetic resonance (¹³C-NMR) spectra and electron paramagnetic resonance (EPR) spectra.

Molecular dynamics (MD) & molecular modeling

 * Finite element method, FEM, aka finite element analysis (FEA): numerical technique for finding approximate solutions of partial differential equations (PDE) as well as of integral equations.
 * Gaussian network model, also elastic network models (ENM): representation of a biological macromolecule as an elastic mass-and-spring network to study, understand, and characterize mechanical aspects of its long-scale dynamics.
 * Anisotropic Network Model: essentially an Elastic Network Model for the Cα atoms  with a step function for the dependence of the force constants on the inter-particle distance.


 * List of software for nanostructures modeling: more material sciences
 * Comparison of software for molecular mechanics modeling: MD simulations. Software: Abalone, Ascalaph Designer, HyperChem, LAMMPS, MAPS, Materials Studio, TINKER.


 * PyMOL
 * UCSF Chimera
 * Coot (program)

Chromatography, mass spectrometry software

 * Category:Mass spectrometry software
 * Category:Chromatography software


 * Chromatography software


 * OpenChrom: open source software for the analysis and visualization of mass spectrometric and chromatographic data. Its focus is to handle native data files from several mass spectrometry systems (e.g. GC/MS, LC/MS, Py-GC/MS, HPLC-MS), vendors like Agilent Technologies, Varian, Shimadzu, Thermo Fisher, PerkinElmer and others.

Surface science

 * Category:Surface science
 * Category:Colloidal chemistry


 * Interface and colloid science: intersection of branches of chemistry, physics, nanoscience and other fields dealing with colloids, heterogeneous systems consisting of a mechanical mixture of particles between 1 nm and 1000 nm dispersed in a continuous medium.
 * Double layer (interfacial) (DL; electrical double layer, EDL): structure that appears on the surface of an object when it is exposed to a fluid
 * Point of zero charge (pzc): physical chemistry: is a concept relating to the phenomenon of adsorption, and it describes the condition when the electrical charge density on a surface is zero; electrochemistry: electrode potential at the point of zero charge.
 * Zeta potential: electrokinetic potential in colloidal systems. In the colloidal chemistry literature, it is usually denoted using the Greek letter zeta (ζ), hence ζ-potential; electric potential in the interfacial double layer at the location of the slipping plane versus a point in the bulk fluid away from the interface
 * Debye length (Debye radius): measure of a charge carrier's net electrostatic effect in solution, and how far those electrostatic effects persist; Debye sphere is a volume whose radius is the Debye length, in which there is a sphere of influence, and outside of which charges are electrically screened
 * Particle aggregation: formation of clusters in a colloidal suspension and represents the most frequent mechanism leading to destabilization of colloidal systems
 * Non-stick surface: surface engineered to reduce the ability of other materials to stick to it. Non-stick cookware is a common application, where the non-stick coating allows food to brown without sticking to the pan. Non-stick is often used to refer to surfaces coated with polytetrafluoroethylene (PTFE), a well-known brand of which is Teflon. In the twenty-first century, other coatings have been marketed as non-stick, such as anodized aluminium, silica, enameled cast iron, and seasoned cookware.

Surfactants

 * Category:Colloidal chemistry
 * Category:Surfactants
 * Category:Cationic surfactants
 * Category:Phospholipids
 * Category:Zwitterionic surfactants


 * Surfactant: compounds that lower the surface tension (or interfacial tension) between two liquids or between a liquid and a solid. Surfactants may act as detergents, wetting agents, emulsifiers, foaming agents, and dispersants. Surface active agent.

Medicinal chemistry

 * Category:Medicinal chemistry

{q.v. User:Kazkaskazkasako/Work}


 * Medicinal chemistry: discipline at the intersection of chemistry, especially synthetic organic chemistry, and pharmacology and various other biological specialties, where they are involved with design, chemical synthesis and development for market of pharmaceutical agents, or bio-active molecules (drugs). Compounds used as medicines are most often organic compounds, which are often divided into the broad classes of small organic molecules and "biologics" (infliximab (chimeric monoclonal antibody), erythropoietin, insulin glargine), the latter of which are most often medicinal preparations of proteins (natural and recombinant antibodies, hormones etc.). Inorganic and organometallic compounds are also useful as drugs (e.g., lithium and platinum-based agents such as lithium carbonate and cisplatin as well as gallium). In the path of drug discovery: Discovery; Hit to lead and lead optimization; Process chemistry and development; Synthetic analysis; Structural analysis.

Combustion, fire

 * Category:Combustion
 * Category:Fire
 * Category:Fires
 * Category:Fires by type
 * Category:Industrial fires and explosions
 * Category:Dust explosions
 * Category:Thermobaric weapons


 * Dust explosion: rapid combustion of fine particles suspended in the air within an enclosed location. Dust explosions can occur where any dispersed powdered combustible material is present in high-enough concentrations in the atmosphere or other oxidizing gaseous medium, such as pure oxygen. In cases when fuel plays the role of a combustible material, the explosion is known as a fuel-air explosion. Dust explosions are a frequent hazard in coal mines, grain elevators, and other industrial environments. They are also commonly used by special effects artists, filmmakers, and pyrotechnicians, given their spectacular appearance and ability to be safely contained under certain carefully controlled conditions.


 * Thermobaric weapon: thermobaric weapon, also called an aerosol bomb, a vacuum bomb or a fuel air explosive (FAE), is a type of explosive that uses oxygen from the surrounding air to generate a high-temperature explosion. The fuel–air explosive is one of the best-known types of thermobaric weapons. Thermobaric weapons are almost 100% fuel and as a result are significantly more energetic than conventional explosives of equal weight.

Astronomy, space technology

 * Category:Astronomy
 * Category:Astronomical sub-disciplines
 * Category:Astrochemistry
 * Category:Astrophysics
 * Category:Planetary science
 * Category:Physical cosmology
 * Category:Stellar astronomy
 * Category:Astronomical objects
 * Category:Outer space
 * Category:Interstellar media
 * Category:Space photography and videography
 * Category:Photography and videography of Earth from space
 * Category:Local Bubble


 * Timeline of first images of Earth from space




 * Astronomy: natural science that studies celestial objects and phenomena. It applies mathematics, physics, and chemistry, in an effort to explain the origin of those objects and phenomena and their evolution. Objects of interest include planets, moons, stars, galaxies, and comets; the phenomena include supernova explosions, gamma ray bursts, and cosmic microwave background radiation. A related but distinct subject, physical cosmology, is concerned with the study of the Universe as a whole. Astronomy is one of the oldest of the natural sciences. The early civilizations in recorded history, such as the Babylonians, Greeks, Indians, Egyptians, Nubians, Iranians, Chinese, Maya, and many ancient indigenous peoples of the Americas performed methodical observations of the night sky. Use of terms "astronomy" and "astrophysics": Generally, either the term "astronomy" or "astrophysics" may be used to refer to this subject; since most modern astronomical research deals with subjects related to physics, modern astronomy could actually be called astrophysics.
 * Epoch (astronomy): moment in time used as a reference point for some time-varying astronomical quantity. It is useful for the celestial coordinates or orbital elements of a celestial body, as they are subject to perturbations and vary with time. These time-varying astronomical quantities might include, for example, the mean longitude or mean anomaly of a body, the node of its orbit relative to a reference plane, the direction of the apogee or aphelion of its orbit, or the size of the major axis of its orbit.


 * Astronomical coordinate systems: organized arrangements for specifying positions of satellites, planets, stars, galaxies, and other celestial objects relative to physical reference points available to a situated observer (e.g. the true horizon and north cardinal direction to an observer situated on the Earth's surface). Coordinate systems in astronomy can specify an object's position in three-dimensional space or plot merely its direction on a celestial sphere, if the object's distance is unknown or trivial. Spherical coordinates, projected on the celestial sphere, are analogous to the geographic coordinate system used on the surface of Earth. These differ in their choice of fundamental plane, which divides the celestial sphere into two equal hemispheres along a great circle. Rectangular coordinates, in appropriate units, have the same fundamental (x, y) plane and primary (x-axis) direction, such as a rotation axis. Each coordinate system is named after its choice of fundamental plane.
 * Ecliptic coordinate system: commonly used for representing the apparent positions, orbits, and pole orientations of Solar System objects. Because most planets (except Mercury) and many small Solar System bodies have orbits with only slight inclinations to the ecliptic, using it as the fundamental plane is convenient. The system's origin can be the center of either the Sun or Earth, its primary direction is towards the vernal (March) equinox, and it has a right-hand convention. It may be implemented in spherical or rectangular coordinates.
 * Equinox (celestial coordinates): in astronomy is either of two places on the celestial sphere at which the ecliptic intersects the celestial equator. Although there are two such intersections, the equinox associated with the Sun's ascending node is used as the conventional origin of celestial coordinate systems and referred to simply as "the equinox". In contrast to the common usage of spring/vernal and autumnal equinoxes, the celestial coordinate system equinox is a direction in space rather than a moment in time. In a cycle of about 25,800 years, the equinox moves westward with respect to the celestial sphere because of perturbing forces; therefore, in order to define a coordinate system, it is necessary to specify the date for which the equinox is chosen. This date should not be confused with the epoch. Astronomical objects show real movements such as orbital and proper motions, and the epoch defines the date for which the position of an object applies. Therefore, a complete specification of the coordinates for an astronomical object requires both the date of the equinox and of the epoch.


 * Julian year (astronomy): unit of measurement of time defined as exactly 365.25 days of 86400 SI seconds each. The length of the Julian year is the average length of the year in the Julian calendar that was used in Western societies until the adoption of the Gregorian Calendar, and from which the unit is named. Nevertheless, because astronomical Julian years are measuring duration rather than designating dates, this Julian year does not correspond to years in the Julian calendar or any other calendar. Nor does it correspond to the many other ways of defining a year. Usage: the Julian year is defined in terms of the SI unit one second, so is as accurate as that unit and is constant. It approximates both the sidereal year and the tropical year to about ±0.008 days. The Julian year is the basis of the definition of the light-year as a unit of measurement of distance.


 * International Astronomical Union (IAU; fr: Union astronomique internationale, UAI): nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and development through global cooperation. It was founded in 1919 and is based in Paris, France. The Union is best known for being the leading authority in assigning official names and designations to astronomical objects, and for setting uniform definitions for astronomical principles. It also coordinates with national and international partners, such as UNESCO, to fulfill its mission. The IAU is a member of the ISC, which is composed of international scholarly and scientific institutions and national academies of sciences.


 * Astronaut (astronaut (in the U.S.) or cosmonaut (in Russia) or taikonaut (in China)): person trained by a human spaceflight program to command, pilot, or serve as a crew member of a spacecraft. Until 2002, astronauts were sponsored and trained exclusively by governments, either by the military, or by civilian space agencies . With the sub-orbital flight of the privately funded SpaceShipOne in 2004, a new category of astronaut was created: the commercial astronaut.


 * Astronomical object (celestial object): naturally occurring physical entity, association, or structure that exists in the observable universe. In astronomy, the terms object and body are often used interchangeably. However, an astronomical body or celestial body is a single, tightly bound, contiguous entity, while an astronomical or celestial object is a complex, less cohesively bound structure, which may consist of multiple bodies or even other objects with substructures. Examples of astronomical objects include planetary systems, star clusters, nebulae, and galaxies, while asteroids, moons, planets, and stars are astronomical bodies. A comet may be identified as both body and object: It is a body when referring to the frozen nucleus of ice and dust, and an object when describing the entire comet with its diffuse coma and tail.

Astrometry

 * Category:Astrometry
 * Category:Parallax
 * Category:Physical cosmology


 * Stellarparallax parsec1.svg


 * Astronomical unit (au, AU): unit of length, roughly the distance from Earth to the Sun and equal to about 150 mln. km or ~8 light minutes. The actual distance varies by about 3% as Earth orbits the Sun.
 * Parsec (pc): unit of length used to measure the large distances to astronomical objects outside the Solar System, approximately equal to 3.26 ly or 206,000 au, $3.086 m$. Parsec is obtained by the use of parallax and trigonometry, and is defined as the distance at which one astronomical unit subtends an angle of one arcsecond ($1⁄3600$ of a degree). The nearest star, Proxima Centauri, is about 1.3 pc (4.2 ly) from the Sun. The word parsec, from the parallax of one arcsecond, was coined by the British astronomer Herbert Hall Turner in 1913 to make calculations of astronomical distances from only raw observational data easy for astronomers. Partly for this reason, it is the unit preferred in astronomy and astrophysics, though the light-year remains prominent in popular science texts and common usage.


 * Cosmic distance ladder (extragalactic distance scale): succession of methods by which astronomers determine the distances to celestial objects. A real direct distance measurement of an astronomical object is possible only for those objects that are "close enough" (within about a thousand parsecs) to Earth. The techniques for determining distances to more distant objects are all based on various measured correlations between methods that work at close distances and methods that work at larger distances. Several methods rely on a standard candle, which is an astronomical object that has a known luminosity.
 * Direct measurement: au, pc.
 * Standard candles: Two problems exist for any class of standard candle. The principal one is calibration, that is the determination of exactly what the absolute magnitude of the candle is. This includes defining the class well enough that members can be recognized, and finding enough members of that class with well-known distances to allow their true absolute magnitude to be determined with enough accuracy. The second problem lies in recognizing members of the class, and not mistakenly using a standard candle calibration on an object which does not belong to the class.
 * Standard siren: Gravitational waves originating from the inspiral phase of compact binary systems, such as neutron stars or black holes, have the useful property that energy emitted as gravitational radiation comes exclusively from the orbital energy of the pair, and the resultant shrinking of their orbits is directly observable as an increase in the frequency of the emitted gravitational waves.

Astronomical imaging

 * Category:Astronomical imaging
 * Category:Speckle imaging
 * Category:Telescopes
 * Category:Telescopes under construction

{q.v. User:Kazkaskazkasako/Books/EECS}


 * Lucky imaging (lucky exposures): one form of speckle imaging used for astronomical photography. Speckle imaging techniques use a high-speed camera with exposure times short enough (100 ms or less) so that the changes in the Earth's atmosphere during the exposure are minimal.


 * Extremely large telescope: astronomical observatory featuring an optical telescope with an aperture for its primary mirror from 20 metres up to 100 metres across, when discussing reflecting telescopes of optical wavelengths including ultraviolet (UV), visible, and near infrared wavelengths. Among many planned capabilities, extremely large telescopes are planned to increase the chance of finding Earth-like planets around other stars.
 * Extremely Large Telescope: astronomical observatory and the world's largest optical/near-infrared extremely large telescope now under construction. Part of the European Southern Observatory (ESO) agency, it is located on top of Cerro Armazones in the Atacama Desert of northern Chile.
 * Giant Magellan Telescope: ground-based ELT under construction, planned for completion in 2025.
 * Thirty Meter Telescope (TMT): proposed astronomical observatory with ELT that has become the source of controversy over its planned location on Mauna Kea in the US state of Hawaii. Construction of the TMT on land which is sacred to Native Hawaiian culture and religion attracted international coverage after October 2014, when construction was temporarily halted voluntarily due to protests.

Astrophysics

 * Category:Astrophysics
 * Category:Celestial mechanics
 * Category:Cosmic rays


 * Astrophysics: branch of astronomy that employs the principles of physics and chemistry "to ascertain the nature of the heavenly bodies, rather than their positions or motions in space." Among the objects studied are the Sun, other stars, galaxies, extrasolar planets, the interstellar medium and the cosmic microwave background. Their emissions are examined across all parts of the electromagnetic spectrum, and the properties examined include luminosity, density, temperature, and chemical composition. Astrophysics is a very broad subject.


 * Cosmic ray: high-energy radiation, mainly originating outside the Solar System and even from distant galaxies. Upon impact with the Earth's atmosphere, cosmic rays can produce showers of secondary particles that sometimes reach the surface. Composed primarily of high-energy protons and atomic nuclei, they are of uncertain origin. During the years from 1930 to 1945, a wide variety of investigations confirmed that the primary cosmic rays are mostly protons, and the secondary radiation produced in the atmosphere is primarily electrons, photons and muons. In 1948, observations with nuclear emulsions carried by balloons to near the top of the atmosphere showed that approximately 10% of the primaries are helium nuclei (alpha particles) and 1% are heavier nuclei of the elements such as carbon, iron, and lead.
 * Sources of cosmic rays: A wide variety of potential sources for cosmic rays began to surface, including supernovae, active galactic nuclei, quasars, and gamma-ray bursts. In February 2013, though, research analyzing data from Fermi revealed through an observation of neutral pion decay that supernovae were indeed a source of cosmic rays, with each explosion producing roughly 3 × 10⁴² – 3 × 10⁴³ J of cosmic rays. However, supernovae do not produce all cosmic rays, and the proportion of cosmic rays that they do produce is a question which cannot be answered without further study.
 * Primary cosmic rays: Primary cosmic ray antimatter: A new measurement of positron fraction up to 500 GeV was reported (2014), showing that positron fraction peaks at a maximum of about 16% of total electron+positron events, around an energy of 275±32 GeV. At higher energies, up to 500 GeV, the ratio of positrons to electrons begins to fall again. The absolute flux of positrons also begins to fall before 500 GeV, but peaks at energies far higher than electron energies, which peak about 10 GeV. Cosmic ray antiprotons also have a much higher average energy than their normal-matter counterparts (protons). They arrive at Earth with a characteristic energy maximum of 2 GeV, indicating their production in a fundamentally different process from cosmic ray protons, which on average have only one-sixth of the energy. Secondary cosmic rays
 * Cosmic-ray flux: In addition, the Earth's magnetic field acts to deflect cosmic rays from its surface, giving rise to the observation that the flux is apparently dependent on latitude, longitude, and azimuth angle.
 * Significance to aerospace travel: Galactic cosmic rays are one of the most important barriers standing in the way of plans for interplanetary travel by crewed spacecraft. Cosmic rays also pose a threat to electronics placed aboard outgoing probes. In 2010, a malfunction aboard the Voyager 2 space probe was credited to a single flipped bit, probably caused by a cosmic ray. Strategies such as physical or magnetic shielding for spacecraft have been considered in order to minimize the damage to electronics and human beings caused by cosmic rays.
 * Oh-My-God particle: ultra-high-energy cosmic ray detected on the evening of 15 October 1991 over Dugway Proving Ground, Utah, by the University of Utah's Fly's Eye Cosmic Ray Detector. Its observation was a shock to astrophysicists (hence the name), who estimated its energy to be approximately 3×10²⁰ eV or 3×10⁸ TeV. The particle had a kinetic energy of 48 joules, equivalent to a 142-gram baseball travelling at about 26 m/s (94 km/h). This particle had so much kinetic energy for its size because it was travelling at 99.99999999999999999999951% of the speed of light. As a result, its Lorentz factor was 3.2×10¹¹. This is so near the speed of light that if a photon were travelling with the particle, it would take over 215,000 years for the photon to gain a 1 cm lead as seen in Earth's reference frame. Since the first observation, at least 72 similar (energy > 5.7×10¹⁹ eV) events have been recorded, confirming the phenomenon.
 * Ultra-high-energy cosmic ray (UHECR): cosmic ray particle with a kinetic energy greater than 1×10¹⁸ eV, far beyond both the rest mass and energies typical of other cosmic ray particles. An extreme-energy cosmic ray (EECR) is an UHECR with energy exceeding 5×10¹⁹ eV (about 8 joule), the so-called Greisen–Zatsepin–Kuzmin limit (GZK limit). This limit should be the maximum energy of cosmic ray protons that have traveled long distances (about 160 million light years), since higher-energy protons would have lost energy over that distance due to scattering from photons in CMB. It follows that EECR could not be survivors from the early universe, but are cosmologically "young", emitted somewhere in the Local Supercluster by some unknown physical process. If an EECR is not a proton, but a nucleus with $$A$$ nucleons, then the GZK limit applies to its nucleons, which carry only a fraction $$1/A$$ of the total energy of the nucleus. In 2007, PAO tentatively associated EECR with extragalactic supermassive black holes at the center of nearby galaxies called active galactic nuclei (AGN). Extremely high energies might be explained also by the Centrifugal mechanism of acceleration in the magnetospheres of AGN. Although newer results indicate that fewer than 40% of these cosmic rays seemed to be coming from the AGN, a much weaker correlation than previously reported. Suggested explanations: Neutron stars, Active galactic cores, Relation with dark matter.
 * Health threat from cosmic rays: danger posed by galactic cosmic rays (GCR) and solar energetic particles to astronauts on interplanetary missions or any missions that venture through the Van-Allen Belts or outside the Earth's magnetosphere. They are one of the greatest barriers standing in the way of plans for interplanetary travel by crewed spacecraft, but space radiation health risks also occur for missions in low Earth orbit such as ISS. GCRs consist of high energy protons (85%), helium (14%) and other high energy nuclei (HZE ions). Solar energetic particles consist primarily of protons accelerated by the Sun to high energies via proximity to solar flares and coronal mass ejections. Astronauts on Apollo and Skylab missions received on average 1.2 mSv/day and 1.4 mSv/day respectively. Since the durations of the Apollo and Skylab missions were days and months, respectively, rather than years, the doses involved were smaller than would be expected on future long-term missions such as to a near-Earth asteroid or to Mars (unless far more shielding could be provided). 2013.05.31 NASA scientists reported that a possible manned mission to Mars may involve a great radiation risk based on the amount of energetic particle radiation detected by the radiation assessment detector (RAD) on the Mars Science Laboratory while traveling from the Earth to Mars in 2011–2012.


 * Gamma-ray burst: immensely energetic explosions that have been observed in distant galaxies. They are the most energetic and luminous electromagnetic events since the Big Bang. Bursts can last from ten milliseconds to several hours. After an initial flash of gamma rays, a longer-lived "afterglow" is usually emitted at longer wavelengths (X-ray, ultraviolet, optical, infrared, microwave and radio). The intense radiation of most observed GRBs is thought to be released during a supernova or superluminous supernova as a high-mass star implodes to form a neutron star or a black hole. A subclass of GRBs (the "short" bursts) appear to originate from the merger of binary neutron stars. The cause of the precursor burst observed in some of these short events may be the development of a resonance between the crust and core of such stars as a result of the massive tidal forces experienced in the seconds leading up to their collision, causing the entire crust of the star to shatter. The sources of most GRBs are billions of light years away from Earth, implying that the explosions are both extremely energetic (a typical burst releases as much energy in a few seconds as the Sun will in its entire 10-billion-year lifetime) and extremely rare (a few per galaxy per million years). All observed GRBs have originated from outside the Milky Way galaxy, although a related class of phenomena, soft gamma repeater flares, are associated with magnetars within the Milky Way. It has been hypothesized that a gamma-ray burst in the Milky Way, pointing directly towards the Earth, could cause a mass extinction event.
 * Very-high-energy gamma ray: gamma radiation with photon energies of 100 GeV (gigaelectronvolt) to 100 TeV (teraelectronvolt), i.e., 1011 to 1014 eV, wavelengths between 10−17 and 10−20 meters, or frequencies of 2 × 1025 to 2 × 1028 Hz. Such energy levels have been detected from emissions from astronomical sources such as some binary star systems containing a compact object.
 * Ultra-high-energy gamma ray: with photon energies higher than 100 TeV (0.1 PeV). They have a frequency higher than 2.42 × 1028 Hz and a wavelength shorter than 1.24 × 10−20 m.

Astrochemistry

 * Category:Astrochemistry

{q.v. }


 * Nucleosynthesis periodic table.svg


 * Astrochemistry: study of the abundance and reactions of molecules in the Universe, and their interaction with radiation. The discipline is an overlap of astronomy and chemistry. The word "astrochemistry" may be applied to both the Solar System and the interstellar medium. The study of the abundance of elements and isotope ratios in Solar System objects, such as meteorites, is also called cosmochemistry, while the study of interstellar atoms and molecules and their interaction with radiation is sometimes called molecular astrophysics.


 * Abundance of the chemical elements: measure of the occurrence of the chemical elements relative to all other elements in a given environment. Abundance is measured in one of three ways: by the mass-fraction (the same as weight fraction); by the mole-fraction (fraction of atoms by numerical count, or sometimes fraction of molecules in gases); or by the volume-fraction. Volume-fraction is a common abundance measure in mixed gases such as planetary atmospheres, and is similar in value to molecular mole-fraction for gas mixtures at relatively low densities and pressures, and ideal gas mixtures. Most abundance values in this article are given as mass-fractions. The abundance of elements in the Sun and outer planets is similar to that in the universe. Due to solar heating, the elements of Earth and the inner rocky planets of the Solar System have undergone an additional depletion of volatile hydrogen, helium, neon, nitrogen, and carbon (which volatilizes as methane). The crust, mantle, and core of the Earth show evidence of chemical segregation plus some sequestration by density. Lighter silicates of aluminium are found in the crust, with more magnesium silicate in the mantle, while metallic iron and nickel compose the core. The abundance of elements in specialized environments, such as atmospheres, or oceans, or the human body, are primarily a product of chemical interactions with the medium in which they reside.

Space science

 * Category:Space science


 * Outline of space science: encompasses all of the scientific disciplines that involve space exploration and study natural phenomena and physical bodies occurring in outer space, such as space medicine and astrobiology.

Astrobiology

 * Category:Astrobiology
 * Category:Anthropic principle
 * Category:Extraterrestrial life
 * Category:Search for extraterrestrial intelligence
 * Category:Planetary habitability
 * Category:Search for extraterrestrial intelligence
 * Category:Radio astronomy
 * Category:Search for extraterrestrial intelligence
 * Category:Extraterrestrial life
 * Category:Physical cosmology
 * Category:Anthropic principle


 * Drake equation: probabilistic argument used to estimate the number of active, communicative extraterrestrial civilizations in the Milky Way Galaxy. The equation was formulated in 1961 by Frank Drake, not for purposes of quantifying the number of civilizations, but as a way to stimulate scientific dialogue at the first scientific meeting on the search for extraterrestrial intelligence (SETI). The equation summarizes the main concepts which scientists must contemplate when considering the question of other radio-communicative life. It is more properly thought of as an approximation than as a serious attempt to determine a precise number. $$N = R_* \cdot f_\mathrm{p} \cdot n_\mathrm{e} \cdot f_\mathrm{l} \cdot f_\mathrm{i} \cdot f_\mathrm{c} \cdot L$$
 * Fermi paradox: apparent contradiction between high estimates of the probability of the existence of extraterrestrial civilizations, such as in the Drake equation, and the lack of evidence for such civilizations. Hypothetical explanations for the paradox: No other civilizations have arisen; It is the nature of intelligent life to destroy itself; It is the nature of intelligent life to destroy others; Life is periodically destroyed by naturally occurring events; Inflation hypothesis and the youngness argument; Intelligent civilizations are too far apart in space or time; It is too expensive to spread physically throughout the galaxy; Humans are not listening properly; Everyone is listening, no one is transmitting; Earth is purposely isolated (planetarium hypothesis); It is dangerous to communicate; The Fermi paradox itself is what prevents communication
 * Great Filter: one possible resolution of the Fermi paradox. It posits that in the development of life from the earliest stages of abiogenesis to reaching the highest levels of development on the Kardashev scale, there exists some particular barrier to development that makes detectable extraterrestrial life exceedingly rare. The concept originates in Robin Hanson's argument that the failure to find any extraterrestrial civilizations in the observable universe implies that something is wrong with one or more of the arguments (from various scientific disciplines) that the appearance of advanced intelligent life is probable; this observation is conceptualized in terms of a "Great Filter" which acts to reduce the great number of sites where intelligent life might arise to the tiny number of intelligent species with advanced civilizations actually observed (currently just one: human). This probability threshold, which could lie in the past or following human extinction, might work as a barrier to the evolution of intelligent life, or as a high probability of self-destruction. The main conclusion of this argument is that the easier it was for life to evolve to the present stage, the bleaker the future chances of humanity probably are.
 * Zoo hypothesis: speculates on the assumed behavior and existence of technically advanced extraterrestrial life and the reasons they refrain from contacting Earth. It is one of many theoretical explanations for the Fermi paradox. The hypothesis is that alien life intentionally avoids communication with Earth, and one of its main interpretations is that it does so to allow for natural evolution and sociocultural development, avoiding interplanetary contamination, similarly to people observing animals at a zoo. In the related laboratory hypothesis, the zoo hypothesis is extended such that the 'zoo keepers' are subjecting humanity to experiments, a hypothesis which Ball describes as "morbid" and "grotesque", overlooking the possibility that such experiments may be altruistic, i.e., designed to accelerate the pace of civilization to overcome a tendency for intelligent life to destroy itself, until a species is sufficiently developed to establish contact, as in the zoo hypothesis.
 * Dark forest hypothesis: conjecture that many alien civilizations exist throughout the universe, but they are both silent and hostile, maintaining their undetectability by humanity for fear of being destroyed by another hostile and undetected civilization. In this framing, it is presumed that any space-faring civilization would view any other intelligent life as an inevitable threat, and thus destroy any nascent life that makes itself known. As a result, the electromagnetic spectrum would be relatively quiet, without evidence of any intelligent alien life, as in a "dark forest" filled with "armed hunter(s) stalking through the trees like ghosts".
 * Relationship to other proposed Fermi paradox solutions: The dark forest hypothesis is distinct from the berserker hypothesis in that many alien civilizations would still exist if they kept silent. It can be viewed as a special example of the Berserker hypothesis, if the 'deadly berserker probes' are (due to resource scarcity) only sent to star systems that show signs of intelligent life.
 * Game theory: dark forest hypothesis is a special case of the "sequential and incomplete information game" in game theory. In game theory, a "sequential and incomplete information game" is one in which all players act in sequence, one after the other, and none are aware of all available information. In the case of this particular game, the only win condition is continued survival. An additional constraint in the special case of the "dark forest" is the scarcity of vital resources. The "dark forest" can be considered an extensive-form game with each "player" possessing the following possible actions: destroy another civilization known to the player; broadcast and alert other civilizations of one's existence; or do nothing.
 * Neocatastrophism: hypothesis that life-exterminating events such as gamma-ray bursts have acted as a galactic regulation mechanism in the Milky Way upon the emergence of complex life in its habitable zone. It is one of several proposed solutions to the Fermi paradox since it provides a mechanism which would have delayed the advent of intelligent beings in local galaxies near Earth. Part of the neocatastrophism hypothesis is that stellar evolution produces a decreasing frequency of such catastrophic events increasing the length of the "window" in which intelligent life might arise as galaxies age. According to modeling, this creates the possibility of a phase transition at which point a galaxy turns from a place that is essentially dead (with a few pockets of simple life) to one that is crowded with complex life forms.
 * Kardashev scale: method of measuring a civilization's level of technological advancement, based on the amount of energy a civilization is able to utilize directed towards communication. The scale has three designated categories called Type I, II, and III. A Type I civilization is able to utilize and store energy available from its neighboring star which reaches their planet, Type II is able to harnesses the energy of the entire star (hypothetic concept: the Dyson Sphere), and Type III civilization are galactic travelers and posses knowledge of everything having to do with energy. Information mastery (Carl Sagan); Microdimensional mastery (John Barrow); Civilizational range (Robert Zubrin).


 * Rare Earth hypothesis: argues that the origin of life and the evolution of biological complexity such as sexually reproducing, multicellular organisms on Earth (and, subsequently, human intelligence) required an improbable combination of astrophysical and geological events and circumstances. According to the hypothesis, complex extraterrestrial life is an improbable phenomenon and likely to be rare throughout the universe as a whole. The term "Rare Earth" originates from Rare Earth: Why Complex Life Is Uncommon in the Universe (2000), a book by Peter Ward, a geologist and paleontologist, and Donald E. Brownlee, an astronomer and astrobiologist, both faculty members at the University of Washington. In the 1970s and 1980s, Carl Sagan and Frank Drake, among others, argued that Earth is a typical rocky planet in a typical planetary system, located in a non-exceptional region of a common barred spiral galaxy. From the principle of mediocrity (extended from the Copernican principle), they argued that the evolution of life on Earth, including human beings, was also typical, and therefore that the universe teems with complex life. However, Ward and Brownlee argue that planets, planetary systems, and galactic regions that are as accommodating for complex life as are the Earth, the Solar System, and our own galactic region are not typical at all, but actually exceedingly rare.


 * Circumstellar habitable zone (CHZ, habitable zone, Goldilocks zone): range of orbits around a star within which a planetary surface can support liquid water given sufficient atmospheric pressure. The bounds of the CHZ are based on Earth's position in the Solar System and the amount of radiant energy it receives from the Sun. Due to the importance of liquid water to Earth's biosphere, the nature of the CHZ and the objects within it may be instrumental in determining the scope and distribution of planets capable of supporting Earth-like extraterrestrial life and intelligence. 2013.11.04, astronomers reported, based on Kepler data, that there could be as many as 40 billion Earth-sized planets orbiting in the habitable zones of Sun-like stars and red dwarfs in the Milky Way. About 11 billion of these may be orbiting Sun-like stars. Proxima Centauri b, located about 4.2 light-years (1.3 parsecs) from Earth in the constellation of Centaurus, is the nearest known exoplanet, and is orbiting in the habitable zone of its star. The CHZ is also of particular interest to the emerging field of habitability of natural satellites, because planetary-mass moons in the CHZ might outnumber planets.
 * Habitability of natural satellites: measure of the potential of natural satellites to have environments hospitable to life. Habitable environments do not necessarily harbor life. Natural satellite habitability is an emerging field which is considered important to astrobiology for several reasons, foremost being that natural satellites are predicted to greatly outnumber planets and it is hypothesized that habitability factors are likely to be similar to those of planets. There are, however, key environmental differences which have a bearing on moons as potential sites for extraterrestrial life.


 * Exomoon (extrasolar moon): natural satellite that orbits an exoplanet or other non-stellar extrasolar body. It is inferred from the empirical study of natural satellites in the Solar System that they are likely to be common elements of planetary systems. The majority of detected exoplanets are giant planets. In the Solar System, the giant planets have large collections of natural satellites (see Moons of Jupiter, Moons of Saturn, Moons of Uranus and Moons of Neptune). Therefore, it is reasonable to assume that exomoons are equally common.


 * Search for extraterrestrial intelligence (SETI): collective term for scientific searches for intelligent extraterrestrial life, for example, monitoring electromagnetic radiation for signs of transmissions from civilizations on other planets. Scientific investigation began shortly after the advent of radio in the early 1900s, and focused international efforts have been going on since the 1980s. In 2015, Stephen Hawking and Russian billionaire Yuri Milner announced a well-funded effort called Breakthrough Listen. Ongoing radio searches; Community SETI projects;
 * Optical experiments: lasers are highly "monochromatic", that is, they emit light only on one frequency, making it troublesome to figure out what frequency to look for. However, emitting light in narrow pulses results in a broad spectrum of emission; the spread in frequency becomes higher as the pulse width becomes narrower, making it easier to detect an emission.
 * Search for extraterrestrial artifacts; Technosignatures; Post-detection disclosure protocol
 * Breakthrough Listen: project for SETI in the Universe. With $100 million in funding and thousands of hours of dedicated telescope time on state-of-the-art facilities, it is the most comprehensive search for alien communications to date. The project began in January 2016, and is expected to continue for 10 years. The project uses radio wave observations from the Green Bank Observatory and the Parkes Observatory, and visible light observations from the Automated Planet Finder. Targets for the project include one million nearby stars and the centers of 100 galaxies. All data generated from the project are available to the public, and SETI@Home is used for some of the data analysis. The first results were published in April 2017, with further updates expected every 6 months. Together, the radio telescopes will cover ten times more sky than previous searches and scan the entire 1-to-10 GHz range, the so-called "quiet zone" in the spectrum where radio waves are unobscured by cosmic sources or Earth's atmosphere. The project is the most comprehensive search for alien communications to date. It is estimated that the project will generate as much data in one day as previous SETI projects generated in one year. Compared to previous programs, the radio surveys cover 10 times more of the sky, at least 5 times more of the radio spectrum, and work 100 times faster. The optical laser survey is also the deepest and broadest search in history.
 * Targets:
 * All 43 stars within 5 Parsec
 * 1000 stars of all spectral-types within 50 parsecs
 * One million nearby stars
 * Center regions of at least 100 nearby galaxies, including spiral galaxies, elliptical galaxies, dwarf galaxies and irregular galaxies
 * Exotic stars: 20 white dwarfs, 20 neutron stars, 20 black holes
 * Project Cyclops: 1971 NASA project that investigated how SETI should be conducted. As a NASA product the report is in the public domain. The project team created a design for coordinating large numbers of radio telescopes to search for Earth-like radio signals at a distance of up to 1,000 light-years to find intelligent life. The proposed design was shelved due to costs. However, the report became the basis for much of the SETI work to follow.


 * Wow! signal: strong narrowband radio signal received in 1977.08.15, by Ohio State University's Big Ear radio telescope in USA, then used to support the search for extraterrestrial intelligence. The signal appeared to come from the direction of the constellation Sagittarius and bore the expected hallmarks of extraterrestrial origin. The entire signal sequence lasted for the full 72-second window during which Big Ear was able to observe it, but has not been detected since, despite several subsequent attempts by Ehman and others. Many hypotheses have been advanced on the origin of the emission, including natural and human-made sources, but none of them adequately explain the signal.
 * Fast radio burst (FRB): transient radio pulse of length ranging from a fraction of a millisecond to a few milliseconds, caused by some high-energy astrophysical process not yet understood. Astronomers estimate the average FRB releases as much energy in a millisecond as the sun puts out in 3 days. While extremely energetic at their source, the strength of the signal reaching Earth has been described as 1,000 times less than from a mobile phone on the Moon.


 * Active SETI: attempt to send messages to intelligent extraterrestrial life. Active SETI messages are usually sent in the form of radio signals. Physical messages like that of the Pioneer plaque may also be considered an active SETI message. Active SETI is also known as METI (Messaging to Extra-Terrestrial Intelligence). Radio message construction: anticryptography; Error correction. Potential risk. Beacon proposals: 2018 study estimated a 1 to 2 megawatt infrared laser focused through a 30 to 45 meter telescope could be seen from about 20,000 light years away.
 * Communication with extraterrestrial intelligence (CETI): focuses on composing and deciphering interstellar messages that theoretically could be understood by another technological civilization. CETI research has focused on four broad areas: mathematical languages, pictorial systems such as the Arecibo message, algorithmic communication systems (ACETI), and computational approaches to detecting and deciphering "natural" language communication. In 2015.02.13, scientists (including Douglas Vakoch, David Grinspoon, Seth Shostak, and David Brin) at an annual meeting of the American Association for the Advancement of Science, discussed Active SETI and whether transmitting a message to possible intelligent extraterrestrials in the cosmos was a good idea. That same week, a statement was released, signed by many in the SETI community, that a "worldwide scientific, political, and humanitarian discussion must occur before any message is sent". Mathematical and scientific languages: Lincos (Lingua cosmica), Astraglossa, Carl Sagan (1985 Contact), A language based on the fundamental facts of science, Busch general-purpose binary language used in Lone Signal transmissions. Pictorial messages: Pioneer probes, Voyager probes, Arecibo message, Cosmic Call messages. Multi-modal messages: Teen-Age Message, Cosmic Call 2 (Cosmic Call 2003) message. Algorithmic messages: CosmicOS, Logic Gate Matrices. Natural language messages. CETI researchers. Interspecies communication.
 * Morse Message (1962): series of brief radio messages in Morse code that were transmitted from the Evpatoria Planetary Radar (EPR) complex and directed to the planet Venus in 1962. The message consisted of three words, all encoded in Morse code: “Мир”, meaning both “peace” and “world” was transmitted from the EPR in 1962.11.19, and the words “Ленин” and “СССР” were transmitted in 1962.11.24 respectively. The message was the first radio broadcast intended for extraterrestrial civilizations in the history of mankind. The signals reflected off the surface of Venus and were received back on Earth 4 minutes, 32.7 seconds and 4 minutes, 44.7 seconds later (for the November 19 and November 24 broadcasts, respectively).


 * Arecibo Observatory: observatory in Barrio Esperanza, Arecibo, Puerto Rico owned by the US NSF. Following two breaks in cables supporting the receiver platform in the prior months, the NSF stated in 2020.11.19 that it was decommissioning the telescope due to safety concerns. In 2020.12.01 the main telescope collapsed before controlled demolition could be conducted.
 * Five-hundred-meter Aperture Spherical Telescope (五百米口径球面射电望远镜; Tianyan (天眼, lit. "Sky's/Heaven's Eye")): radio telescope located in the Dawodang depression, a natural basin in Pingtang County, Guizhou, southwest China. Construction of FAST began in 2011. It observed first light in 2016.09. After three years of testing and commissioning, it was declared fully operational in 2020.01.11. Comparison with Arecibo Telescope.
 * RATAN-600 (РАТАН-600 – радиоастрономический телескоп Академии наук – 600): radio telescope in Zelenchukskaya, Karachay–Cherkess Republic, Russia. It comprises a 576 m diameter circle of rectangular radio reflectors and a set of secondary reflectors and receivers, based at an altitude of 970 m. Each of the 895 2×7.4 m reflectors can be angled to reflect incoming radio waves towards a central conical secondary mirror, or to one of five parabolic cylinders.

Spaceflight, aviation

 * Category:Technology by type
 * Category:Space technology
 * Category:Spaceflight
 * Category:Human spaceflight
 * Category:Astronauts
 * Category:Spacecraft
 * Category:Altitudes in aviation


 * Comparison International Standard Atmosphere space diving.svg


 * Effect of spaceflight on the human body: Significant adverse effects of long-term weightlessness include muscle atrophy and deterioration of the skeleton (spaceflight osteopenia). Other significant effects include a slowing of cardiovascular system functions, decreased production of red blood cells, balance disorders, eyesight disorders and a weakening of the immune system. Additional symptoms include fluid redistribution (causing the "moon-face" appearance typical in pictures of astronauts experiencing weightlessness), loss of body mass, nasal congestion, sleep disturbance, and excess flatulence. In 2018.10, NASA-funded researchers found that lengthy journeys into outer space, including travel to the planet Mars, may substantially damage the gastrointestinal tissues of astronauts. The studies support earlier work that found such journeys could significantly damage the brains of astronauts, and age them prematurely. Motion sickness. Bone and muscle deterioration. Fluid redistribution: Within a few moments of entering a microgravity environment, fluid is immediately re-distributed to the upper body resulting in bulging neck veins, puffy face and sinus and nasal congestion which can last throughout the duration of the trip and is very much like the symptoms of the common cold.
 * Psychological and sociological effects of spaceflight: A Mars return expedition may last two to three years and may involve a crew of four to seven people, although shorter flyby missions of approximately one and half years with only two people have been proposed, as well as one-way missions that include landing on Mars with no return trip planned. Although there are a number of technological and physiological issues involved with such a mission that remain to be worked out, there are also a number of behavioral issues affecting the crew that are being addressed before launching such missions. In preparing for such an expedition, important psychological, interpersonal, and psychiatric issues occurring in human spaceflight missions are under study by national space agencies and others.


 * Armstrong limit: measure of altitude above which atmospheric pressure is sufficiently low that water boils at the normal temperature of the human body. Exposure to pressure below this limit results in a rapid loss of consciousness, followed by a series of changes to cardiovascular and neurological functions, and eventually death, unless pressure is restored within 60–90 seconds. On Earth, the limit is around 18–19 km above sea level, above which atmospheric air pressure drops below 0.0618 atm (6.3 kPa, 47 mmHg, ~1 psi). The term is named after USAF General Harry George Armstrong, who was the first to recognize this phenomenon. At or above the Armstrong limit, exposed body fluids such as saliva, tears, urine, and the liquids wetting the alveoli within the lungs—but not vascular blood (blood within the circulatory system)—will boil away without a full-body pressure suit, and no amount of breathable oxygen delivered by any means will sustain life for more than a few minutes. Blood pressure is a gauge pressure. Well below the Armstrong limit, humans typically require supplemental oxygen in order to avoid hypoxia. For most people, this is typically needed at altitudes above 4,500 m. If the user does not wear a pressure suit or a counter-pressure garment that restricts the movement of their chest, the high pressure air can cause damage to the lungs.


 * G-suit (anti-g suit): flight suit worn by aviators and astronauts who are subject to high levels of acceleration force (g). It is designed to prevent a black-out and g-LOC (g-induced loss of consciousness) caused by the blood pooling in the lower part of the body when under acceleration, thus depriving the brain of blood. The resting g-tolerance of a typical person is anywhere from 3–5 g depending on the person. A g-suit will typically add 1 g of tolerance to that limit. Pilots still need to practice the 'g-straining maneuver' that consists of tensing the abdominal muscles in order to tighten blood vessels so as to reduce blood pooling in the lower body. High g is not comfortable, even with a g-suit. In older fighter aircraft, 6 g was considered a high level, but with modern fighters 9 g or more can be sustained structurally making the pilot the critical factor in maintaining high maneuverability in close aerial combat.


 * List of spaceflight-related accidents and incidents: resulting in human fatality or near-fatality during flight or training for crewed space missions, and testing, assembly, preparation or flight of crewed and robotic spacecraft. Not included are accidents or incidents associated with intercontinental ballistic missile (ICBM) tests, fatality or injury to test animals, uncrewed space flights not resulting in human fatality or serious injury, or Soviet or German rocket-powered aircraft projects of WWII.


 * North American X-15: hypersonic rocket-powered aircraft operated by USAF and NASA as part of the X-plane series of experimental aircraft. The X-15 set speed and altitude records in the 1960s, reaching the edge of outer space and returning with valuable data used in aircraft and spacecraft design. The X-15's official world record for the highest speed ever recorded by a manned, powered aircraft, set in 1967.10 when William J. Knight flew Mach 6.70 at 31,120 m, a speed of 7,274 km/h (2,021 m/s), has remained unbroken as of 2019. During the X-15 program, 13 flights by eight pilots met the Air Force spaceflight criterion by exceeding the altitude of 80 km, thus qualifying these pilots as being astronauts.


 * Neil Armstrong (1930.08.05–2012.08.25): USA astronaut and aeronautical engineer who was the first person to walk on the Moon. He was also a naval aviator, test pilot, and university professor; saw action in the Korean War, flying the Grumman F9F Panther from the aircraft carrier USS Essex. In September 1951, he was hit by anti-aircraft fire while making a low bombing run, and was forced to bail out. After the war, he completed his bachelor's degree at Purdue and became a test pilot at the National Advisory Committee for Aeronautics (NACA) High-Speed Flight Station at Edwards Air Force Base in California; made his first spaceflight as commander of Gemini 8 in March 1966, becoming NASA's first civilian astronaut to fly in space. During this mission with pilot David Scott, he performed the first docking of two spacecraft; the mission was aborted after Armstrong used some of his reentry control fuel to remove a dangerous spin caused by a stuck thruster.

Spacecraft, space agencies, aerospace companies

 * Category:Aerospace companies
 * Category:Aerospace companies by country
 * Category:Aerospace companies of the United States
 * Category:Blue Origin
 * Category:SpaceX
 * Category:Virgin Galactic
 * Category:United Launch Alliance
 * Category:Spacecraft
 * Category:Space agencies
 * Category:NASA
 * Category:European Space Agency (ESA)
 * Category:JAXA
 * Category:Commercial spaceflight




 * Super heavy-lift launch vehicle (SHLLV): launch vehicle capable of lifting more than 50 t of payload into LEO. Flown vehicles: Retired: Saturn V, Space Shuttle, Energia system (USSR); Operational (unproven as super heavy-lift): Falcon Heavy; Suborbital tests: N1 (USSR), SpaceX Starship. Proposed designs: SLS, SpaceX Starship, Long March 9 (PRC), Yenisei (Russia), Blue Origin: New Glenn.


 * Space launch market competition: manifestation of market forces in the launch service provider business. In particular it is the trend of competitive dynamics among payload transport capabilities at diverse prices having a greater influence on launch purchasing than the traditional political considerations of country of manufacture or the national entity using, regulating or licensing the launch service. Following the advent of spaceflight technology in the late 1950s, space launch services came into being, exclusively by national programs. Later in the 20th century commercial operators became significant customers of launch providers. In the early 2010s, privately developed launch vehicle systems and space launch service offerings emerged . Companies now faced economic incentives rather than the principally political incentives of the earlier decades. The space launch business experienced a dramatic lowering of per-unit prices along with the addition of entirely new capabilities, bringing about a new phase of competition in the space launch market.
 * History: In early December 2013, SpaceX flew its first launch to a geosynchronous orbit providing additional credibility to its low prices which had been published since at least 2009. The low launch prices offered by SpaceX, especially for communication satellites flying to geostationary (GTO) orbit, resulted in market pressure on its competitors to lower their own prices. In years prior to 2013, the communications satellite launch market had been dominated by Europe's Arianespace, which flies the Ariane 5, and International Launch Services (ILS), which markets Russia's Proton vehicle. In November 2013 Arianespace announced new pricing flexibility for the "lighter satellites" it carries to orbits aboard its Ariane 5 in response to SpaceX's growing presence in the worldwide launch market, and followed in early 2014 with a request to European governments for additional subsidies to face the competition from SpaceX. Falcon 9 GTO missions 2014 pricing was approximately US$15 million less than a launch on a Chinese Long March 3B. University of Southampton researcher Clemens Rumpf argues that the global launch industry was developed in an "old world where space funding was provided by governments, resulting in a stable foundation for [global] space activities. The money for the space industry [had been] secure and did not encourage risk-taking in the development of new space technologies. ... the space landscape [had not changed much since the mid-1980s]." As a result, the emergence of SpaceX was a surprise to other launch providers "because the need to evolve launcher technology by a giant leap was not apparent to them. SpaceX show[ed] that technology has advanced sufficiently in the last 30 years to enable new, game changing approaches to space access." A 2017 industry-wide view by SpaceNews reported: By 5 July 2017, SpaceX had launched 10 payloads during a bit over 6 months—"outperform[ing] its cadence from earlier years"—and "is well on track to hit the target it set last year of 18 launches in a single year." By comparison, "France-based Arianespace, SpaceX’s chief competitor for commercial telecommunications satellite launches, is launching 11 to 12 times a year using its fleet of three rockets — the heavy-lift Ariane 5, medium-lift Soyuz and light-lift Vega. Russia has the ability to launch a dozen or more times with Proton doing both government and commercial missions, but has operated at a slower cadence the past few years due to launch failures and this year’s discovery of an incorrect material used in some rocket engines. United Launch Alliance, SpaceX’s chief competitor for defense missions, regularly conducts around a dozen or more launches per year, but the Boeing-Lockheed Martin joint venture has only performed four missions" through mid-year 2017.
 * Competition for the American heavy-lift market: As early as 2014.08, media sources noted that the US launch market may have two competitive super-heavy launch vehicles available in the 2020s to launch payloads of 100 metric tons or more to low-Earth orbit. The US government is currently developing the Space Launch System (SLS), a heavy-lift launch vehicle for lifting very large payloads of 70 to 130 tonnes from Earth. On the commercial side, SpaceX has been privately developing their next-generation Starship launch system, featuring fully reusable boosters and spacecraft, and targeting 150 tonnes of payload. Development of the methalox Raptor engine began in 2012, first flight tests were done in 2019. . By 2014, NASASpaceflight.com reported: "SpaceX [had] never openly portrayed its BFR plans in competition with NASA’s SLS. ... However, should SpaceX make solid progress on the development of its BFR over the coming years, it is almost unavoidable that America’s two HLVs will attract comparisons and a healthy debate, potentially at the political level." The Starship is planned to replace the Falcon 9 and Falcon Heavy launch vehicles, as well as the Dragon spacecraft, initially aiming at the Earth-orbit launch market, but explicitly adding substantial capability to support long-duration spaceflight in the cislunar and Mars mission environments. SpaceX intends this approach to bring significant cost savings that will help the company justify the development expense of designing and building the Starship system.
 * Billionaire space race: intense rivalry in NewSpace by recent space entrepreneurs, who entered the space industry as billionaires from other industries, particularly computing. This private industry space race of the 21st century involves sounding rockets to the ignorosphere (mesosphere and thermosphere), orbital launch rockets, and suborbital tourist spaceflights. Russian billionarie Yuri Milner, backing the Breakthrough Starshot project for an interstellar probe; South African-Canadian-American billionaire Elon Musk , behind SpaceX and a project to colonize Mars; American billionaire Jeff Bezos , behind Blue Origin and establishing a true industrial base in space; American billionaire Paul G. Allen, behind Vulcan Aerospace and reducing the cost to launch payload to orbit; British billionaire Richard Branson , behind Virgin Galactic and space tourism, low cost small orbital launchers, and intercontinental suborbital transit.
 * Launch industry response: In June 2019, the European Commission provided funding for a three-year project called RETALT to "[copy the] retro-propulsive engine firing technique used by SpaceX to land its Falcon 9 rocket first stages back on land and on autonomous drone ships." The RETALT project funding of €3 million was provided to the German Space Agency and five European companies to fund a study to "tackle the shortcoming of know-how in reusable rockets in Europe."
 * Effect on related industries: Early information on the Starlink constellation of 4000 satellites operated by SpaceX intended to provide global Internet services, along with a new factory dedicated to manufacturing low-cost smallsat satellites, indicate that the satellite manufacturing industry may "experience a supply shock similar to what the launcher industry is experiencing" in the 2010s [→2020s]. Venture capital investor Steve Jurvetson has indicated that it is not merely the lower launch prices, but the fact that the known prices act as a signal in conveying information to other entrepreneurs who then use that information to bring on new related ventures.
 * Breakthrough Initiatives: science-based program founded in 2015 and funded by Julia and Yuri Milner to search for extraterrestrial intelligence over a span of at least 10 years. Projects: Breakthrough Listen, Breakthrough Message, Breakthrough Starshot, Breakthrough Watch, Breakthrough Enceladus.
 * Breakthrough Enceladus mission: proposed privately funded astrobiology mission by Breakthrough Initiatives founded by Yuri Milner. Its aim is to assess the possibility of life on Saturn's moon Enceladus. NASA will be “providing expert reviewers and feedback on their design". Corey S. Powell, editor-in-chief of Discover magazine, reporting for NBC News stated that the mission was particularly notable as it would "rewrite the rules of space exploration," being potentially the first to find proof of complex life in the solar system, as it is "riskier than anything NASA would attempt on its own." The privately funded probe is estimated to take a decade to build and cost $60 million, while a NASA government funded approach could take over two decades and cost 15 times as much.
 * Private spaceflight: spaceflight or the development of spaceflight technology that is conducted and paid for by an entity other than a government agency. History of commercial space transportation: American deregulation, Russian privatization, Launch alliances, Spaceflight privatization. NewSpace terminology: term "NewSpace" emphasizes the relative modernity of private spaceflight efforts, encompassing international and multinational efforts to privatize spaceflight as a commercial industry. Such corporations fall under the governance of international treaties and national governments.


 * Orbital Sciences Corporation: USA company specializing in the design, manufacture and launch of small- and medium- class space and rocket systems for commercial, military and other government customers. On 2014.04.29, Orbital Sciences announced that it would merge with Alliant Techsystems to create a new company called Orbital ATK, Inc. The merger was completed on February 9, 2015 and Orbital Sciences ceased to exist as an independent entity.
 * Orbital ATK: USA aerospace manufacturer and defense industry company. It was formed in 2015 from the merger of Orbital Sciences Corporation and parts of Alliant Techsystems. Orbital ATK designs, builds and delivers space, defense and aviation-related systems to customers around the world both as a prime contractor and as a merchant supplier.


 * Space debris (space junk, space pollution, space waste, space trash, space garbage): defunct human-made objects in space—principally in Earth orbit—which no longer serve a useful function. These include derelict spacecraft—nonfunctional spacecraft and abandoned launch vehicle stages—mission-related debris, and particularly numerous in Earth orbit, fragmentation debris from the breakup of derelict rocket bodies and spacecraft. Space debris represents a risk to spacecraft.
 * 2009 satellite collision: two communications satellites—the active commercial Iridium 33 and the derelict Russian military Kosmos-2251—accidentally collided at a speed of 11,700 m/s (42,000 km/h) and an altitude of 789 kilometres above the Taymyr Peninsula in Siberia. It was the first time a hypervelocity collision occurred between two satellites – until then, all accidental hypervelocity collisions had involved a satellite and a piece of space debris.


 * Spaceport (or cosmodrome): site for launching (or receiving) spacecraft, by analogy to seaport for ships or airport for aircraft. The word spaceport, and even more so cosmodrome, has traditionally been used for sites capable of launching spacecraft into orbit around Earth or on interplanetary trajectories. However, rocket launch sites for purely sub-orbital flights are sometimes called spaceports, as in recent years new and proposed sites for suborbital human flights have been frequently referred to or named 'spaceports'. Space stations and proposed future bases on the moon are sometimes called spaceports, in particular if intended as a base for further journeys. The term rocket launch site is used for any facility from which rockets are launched. It may contain one or more launch pads or suitable sites to mount a transportable launch pad. It is typically surrounded by a large safety area, often called a rocket range or missile range. The range includes the area over which launched rockets are expected to fly, and within which some components of the rockets may land. Tracking stations are sometimes located in the range to assess the progress of the launches.
 * SpaceX Starbase: spaceport, production, and development facility for Starship rockets, located at Boca Chica, Texas, USA. It has been under construction since the late 2010s by SpaceX.


 * Comparison of orbital launch systems: first list contains rockets that are currently operational or in development; a second list includes all retired rockets.


 * Astrobotic Technology: USA privately held company that is developing space robotics technology for lunar and planetary missions. It was founded in 2007 by Carnegie Mellon professor Red Whittaker and his associates, with the goal of winning the Google Lunar X Prize. The company is based in Pittsburgh, Pennsylvania. The first launch of one of its spacecraft, the Peregrine lunar lander, is expected to take place in July 2021 on a Vulcan Centaur rocket.
 * Planet Labs (formerly Cosmogia, Inc.): USA private Earth imaging company based in San Francisco, CA. Their goal is to image the entirety of the Earth daily to monitor changes and pinpoint trends. The company designs and manufactures Triple-CubeSat miniature satellites called Doves that are then delivered into orbit as secondary payloads on other rocket launch missions. Each Dove is equipped with a high-powered telescope and camera programmed to capture different swaths of Earth. Each Dove Earth observation satellite continuously scans Earth, sending data once it passes over a ground station, by means of a frame image sensor. With acquisition of BlackBridge in 2015.07, Planet Labs had 87 Dove and 5 RapidEye satellites launched into orbit. In 2017, Planet launched an additional 88 Dove satellites, and Google sold its subsidiary Terra Bella and its SkySat satellite constellation to Planet Labs. 2018.09 the company had launched nearly 300 satellites, 150 of which are active. Through a deal funded by Norway’s Climate and Forests Initiative (NICFI), Planet and its partners Airbus and KSAT are providing access to high-resolution basemaps of 64 tropical countries to help combat deforestation.


 * Anti-satellite weapon (ASAT): space weapons designed to incapacitate or destroy satellites for strategic or tactical purposes. Several nations possess operational ASAT systems. Although no ASAT system has yet been utilised in warfare, a few countries (India, Russia, China, and USA) have successfully shot down their own satellites to demonstrate their ASAT capabilities in a show of force. ASAT roles include: defensive measures against an adversary's space-based and nuclear weapons, a force multiplier for a nuclear first strike, a countermeasure against an adversary's anti-ballistic missile defense (ABM), an asymmetric counter to a technologically superior adversary, and a counter-value weapon. Use of ASATs generates space debris, which can threaten other satellites.
 * Kessler syndrome: proposed by NASA scientist Donald J. Kessler in 1978, is a scenario in which the density of objects in LEO due to space pollution is high enough that collisions between objects could cause a cascade in which each collision generates space debris that increases the likelihood of further collisions. In 2009 Kessler wrote that modeling results had concluded that the debris environment was already unstable, "such that any attempt to achieve a growth-free small debris environment by eliminating sources of past debris will likely fail because fragments from future collisions will be generated faster than atmospheric drag will remove them".


 * List of private spaceflight companies (list of non-governmental, or privately owned, entities): focused on developing and/or offering equipment and services geared towards spaceflight, both robotic and human. The list includes both inactive and active entities. Primes: SpaceX, Northrop Grumman Innovation Systems, Blue Origin, ULA (Boeing, Lockheed Martin), Virgin Orbit & Virgin Galactic, ArianeGroup & Arianespace (Airbus), Bigelow Aerospace.


 * Rockets by Astra: on 2021.11.20 at 06:16:00, Astra managed to launch its first successful mission to orbit. Rocket 3.3 (LV0007), carrying a demonstration payload from the US Department of Defense was launched from PSCA, after several unsuccessful launches during 2021. The company's stocks surged by as much as 42% after this feat. Astra has previously manufactured launch vehicles for both commercial and military customers. These launch vehicles are labelled "Rocket 3".


 * Firefly Aerospace: USA private aerospace firm based in Austin, Texas, that develops launch vehicles for commercial launches to orbit. The company completed its $75 million Series A investment round in May 2021, which was led by DADA Holdings. The current company was formed when the assets of the former company Firefly Space Systems were acquired by EOS Launcher in March 2017, which was then renamed Firefly Aerospace.
 * Firefly Alpha (Firefly α): two-stage orbital expendable launch vehicle developed by the American aerospace company Firefly Aerospace to cover the commercial small satellite launch market. Alpha is intended to provide launch options for both full vehicle and ride share customers.


 * Axiom Space: American privately funded space infrastructure developer headquartered in Houston, Texas. Founded in 2016 by Michael T. Suffredini and Kam Ghaffarian, the company is planning commercial missions in 2022 to ISS and aims to own and operate the world's first commercial space station in 2024. The company's leadership team is largely composed of former NASA employees, including former NASA Administrator Charles Bolden. Other key people at the company include astronauts Michael Lopez-Alegria and Brent W. Jett Jr. The company's planned commercial activities include human spaceflight for space tourists, as well as government-funded and commercial astronauts engaging in in-space research, in-space manufacturing, and space exploration.
 * Axiom Orbital Segment: planned modular components of ISS designed by Axiom Space for commercial space activities. Axiom Space gained initial NASA approval for the venture in 2020.01. Axiom Space was later awarded the contract by NASA in 2020.02.28. This orbital station will be separated from the ISS to become its own modular space station, Axiom Station, after the ISS is decommissioned.


 * Maxar Technologies: space technology company headquartered in Westminster, Colorado, USA, specializing in manufacturing communication, Earth observation, radar, and on-orbit servicing satellites, satellite products, and related services. DigitalGlobe and MDA Holdings Company merged to become Maxar Technologies in 2017.10.05. In 2019.05, the company was selected as the provider of the power and propulsion element for the Lunar Gateway developed by NASA.
 * SSL (company) (Space Systems/Loral, LLC (SS/L)): of Palo Alto, California, is a wholly owned manufacturing subsidiary of Maxar Technologies. SSL designs and builds satellites and space systems for a wide variety of government and commercial customers. Its products include high-powered direct-to-home broadcast satellites, commercial weather satellites, digital audio radio satellites, Earth observation satellites and spot-beam satellites for data networking applications.


 * Thales Alenia Space: Franco-Italian aerospace manufacturer. A joint venture between the French technology corporation Thales Group (67%) and Italian defense conglomerate Leonardo (33%), the company is the largest satellite manufacturer in Europe. It is headquartered in Cannes, France. Thales Alenia Space designs and builds various space-related products, notably manufacturing numerous ranges of satellites for telecommunications, navigation, earth observation and space exploration purposes. The company is the second largest industrial participant in ISS, having produced ESA modules for the ISS. It is also building satellites for Galileo, a European global satellite navigation system (GSNS).
 * Telespazio: European spaceflight services company founded in 1961. It is a joint venture owned by Leonardo (67%) and Thales Group (33%) headquartered in Rome. The company manages space infrastructure, such as the Fucino Space Centre - and is involved in programmes including Galileo, EGNOS, Copernicus, COSMO-SkyMed, SICRAL and Göktürk.
 * Thales Group: French multinational company that designs, develops and manufactures electrical systems as well as devices and equipment for the aerospace, defence, transportation and security sectors. The company is headquartered in Paris' business district, La Défense, and its stock is listed on the Euronext Paris.
 * Leonardo S.p.A. (formerly Leonardo-Finmeccanica, originally Finmeccanica): Italian multinational company specialising in aerospace, defence and security. Headquartered in Rome, Italy, the company has 180 sites worldwide. It is the eighth largest defence contractor in the world based on 2018 revenues. The company is partially owned by the Italian government, which holds 30.2% of the company's shares and is its largest shareholder.


 * SpinLaunch: spaceflight technology development company working on mass accelerator technology to move payloads to space. As of 2022.09, the company has raised US$150 million in funding. A number of reasons why this technology may not work have been put forward, including problems with massive spinning objects, potential for catastrophic damage to the payload, incompatibility with traditional liquid rocket fuels, increased atmospheric drag relative to existing technologies, and other potential problems with the idea.

Rockets

 * Category:Aerospace technologies
 * Category:Rocketry
 * Category:Rocket components
 * Category:Rocket propulsion
 * Category:Rocket engines
 * Category:Nuclear spacecraft propulsion


 * Tsiolkovsky rocket equation (ideal rocket equation): mathematical equation that describes the motion of vehicles that follow the basic principle of a rocket: a device that can apply acceleration to itself using thrust by expelling part of its mass with high velocity can thereby move due to the conservation of momentum. It is credited to the Russian scientist Konstantin Tsiolkovsky who independently derived it and published it in 1903, although it had been independently derived and published by the British mathematician William Moore in 1810, and later published in a separate book in 1813. American Robert Goddard also developed it independently in 1912, and German Hermann Oberth derived it independently about 1920. The maximum change of velocity of the vehicle, $$\Delta v$$ (with no external forces acting) is:

$$\Delta v = v_\text{e} \ln \frac{m_0}{m_f} = I_\text{sp} g_0 \ln \frac{m_0}{m_f},$$ where:
 * $$v_\text{e} = I_\text{sp} g_0$$ is the effective exhaust velocity;
 * $$I_\text{sp}$$ is the specific impulse in dimension of time;
 * $$g_0$$ is standard gravity (9.81 m/s²);
 * $$m_0$$ is the initial total mass, including propellant, a.k.a. wet mass;
 * $$m_f$$ is the final total mass without propellant, a.k.a. dry mass.
 * Specific impulse (Isp): measure of how efficiently a reaction mass engine, such as a rocket using propellant or a jet engine using fuel, generates thrust. For engines like cold gas thrusters whose reaction mass is only the fuel they carry, specific impulse is exactly proportional to the effective exhaust gas velocity.




 * Rocket engine: uses stored rocket propellants as the reaction mass for forming a high-speed propulsive jet of fluid, usually high-temperature gas. Rocket engines are reaction engines, producing thrust by ejecting mass rearward, in accordance with Newton's third law. Most rocket engines use the combustion of reactive chemicals to supply the necessary energy, but non-combusting forms such as cold gas thrusters and nuclear thermal rockets also exist. Vehicles propelled by rocket engines are commonly called rockets. Rocket vehicles carry their own oxidizer, unlike most combustion engines, so rocket engines can be used in a vacuum to propel spacecraft and ballistic missiles. Solid-fuel rockets (or solid-propellant rockets or motors), Liquid-propellant rockets, Hybrid rockets, Monopropellant rockets.


 * NERVA: nuclear thermal rocket engine development program that ran for roughly two decades. Its principal objective was to "establish a technology base for nuclear rocket engine systems to be utilized in the design and development of propulsion systems for space mission application". NERVA was a joint effort of the Atomic Energy Commission (AEC) and NASA, and was managed by the Space Nuclear Propulsion Office (SNPO) until the program ended in January 1973. Although NERVA engines were built and tested as much as possible with flight-certified components and the engine was deemed ready for integration into a spacecraft, they never flew in space.


 * Solar electric propulsion (SEP): combination of solar cells and electric thrusters to propel a spacecraft through outer space. This technology has been exploited in a variety of spacecraft by ESA, the JAXA, Indian Space Research Organisation (ISRO) and NASA. SEP has a significantly higher specific impulse than normal chemical rockets, thus requiring less propellant mass to be launched with a spacecraft. The technology has been evaluated for missions to Mars.


 * Composite overwrapped pressure vessel (COPV): vessel consisting of a thin, non-structural liner wrapped with a structural fiber composite, designed to hold a fluid under pressure. The liner provides a barrier between the fluid and the composite, preventing leaks (which can occur through matrix microcracks which do not cause structural failure) and chemical degradation of the structure. In general, a protective shell is applied for protective shielding against impact damage. The most commonly used composites are fiber reinforced polymers (FRP), using carbon and kevlar fibers. The primary advantage of a COPV as compared to a similar sized metallic pressure vessel is lower weight; COPVs, however, carry an increased cost of manufacturing and certification. Failures: COPVs can be subject to complex modes of failure. In 2016, a SpaceX Falcon 9 rocket exploded on the pad due to the failure of a COPV inside the liquid oxygen tank: the failure resulted from accumulation of frozen solid oxygen between the COPV's aluminum liner and composite overwrap in a void or buckle.

Spaceplanes

 * Category:Spaceplanes




 * Boeing X-37 (Orbital Test Vehicle (OTV)): reusable robotic spacecraft. It is boosted into space by a launch vehicle, then re-enters Earth's atmosphere and lands as a spaceplane. The X-37 is operated by the United States Space Force for orbital spaceflight missions intended to demonstrate reusable space technologies. It is a 120-percent-scaled derivative of the earlier Boeing X-40. The X-37 began as a NASA project in 1999, before being transferred to the United States Department of Defense in 2004. Until 2019, the program was managed by Air Force Space Command.

ISS (International Space Station), other space stations

 * Category:International Space Station


 * Space station: spacecraft capable of supporting a human crew in orbit for an extended period of time, and is therefore a type of space habitat. It lacks major propulsion or landing systems. An orbital station or an orbital space station is an artificial satellite (i.e. a type of orbital spaceflight). Stations must have docking ports to allow other spacecraft to dock to transfer crew and supplies. Architecture: Two types of space stations have been flown: monolithic and modular. Monolithic stations consist of a single vehicle and are launched by one rocket. Modular stations consist of two or more separate vehicles that are launched independently and docked on orbit. Modular stations are currently preferred due to lower costs and greater flexibility.

Mir (Мир):
 * Shuttle–Mir program (1993–1998): collaborative 11-mission space program between Russia and the United States that involved USA Space Shuttles visiting the Russian space station Mir, Russian cosmonauts flying on the Shuttle, and an American astronaut flying aboard a Soyuz spacecraft to engage in long-duration expeditions aboard Mir.


 * Template:International Space Station


 * International Space Station (ISS): modular space station (habitable artificial satellite) in low Earth orbit. It is a multinational collaborative project involving five participating space agencies: NASA (United States), Roscosmos (Russia), JAXA (Japan), ESA (Europe), and CSA (Canada). The ownership and use of the space station is established by intergovernmental treaties and agreements. The station serves as a microgravity and space environment research laboratory in which scientific research is conducted in astrobiology, astronomy, meteorology, physics, and other fields. The ISS is suited for testing the spacecraft systems and equipment required for possible future long-duration missions to the Moon and Mars. ISS is the largest artificial object in space and the largest satellite in low Earth orbit, regularly visible to the naked eye from Earth's surface. It maintains an orbit with an average altitude of 400 kilometres by means of reboost manoeuvres using the engines of the Zvezda Service Module or visiting spacecraft. The ISS circles the Earth in roughly 93 minutes, completing 15.5 orbits per day. The station is divided into two sections: the Russian Orbital Segment (ROS) is operated by Russia, while the US Orbital Segment (USOS) is run by the United States as well as many other nations.


 * Nauka (ISS module) (Наука): funded by Roscosmos. Nauka was finally launched on 2021.07.21 14:58 UTC along with the European Robotic Arm, and successfully docked 2021.07.29 13:29 UTC to Zvezda's nadir port, making the first major expansion of the Russian ISS segment for over 20 years. After Nauka docked, it began firing its engine thrusters in error, causing the entire space station to make one and a half full rotations before the module ran out of fuel, enabling ground controllers to stop the rotation and the crew to get it back to its original position an hour later. According to NASA, the ISS crew was never in danger.

Spacecraft

 * Cassini–Huygens: unmanned spacecraft sent to the planet Saturn; Flagship-class NASA–ESA–ASI robotic spacecraft; Saturn orbiter (Cassini) and a lander (Huygens) for the moon Titan; spacecraft launched 1997.10.15 aboard a Titan IVB/Centaur and entered orbit around Saturn 2004.07.01, after an interplanetary voyage that included flybys of Earth, Venus, and Jupiter. 2004.12.25 Huygens separated from the orbiter, and it landed on Saturn's moon Titan 2005.01.14. Cassini continued to study the Saturn system in the following years, and continues to operate as of 2017.04. Cassini is currently planned to be destroyed by diving into the planet's atmosphere 2017.09.15, when it will beam its last batch of images; this method of disposal was chosen to avoid potential biological contamination of Saturn's moons.
 * Huygens (spacecraft): first and, so far, only landing ever accomplished in the outer Solar System. It touched down on land, although the possibility that it would touch down in an ocean was also taken into account in its design. The probe was designed to gather data for a few hours in the atmosphere, and possibly a short time at the surface. It continued to send data for about 90 minutes after touchdown. It remains the most distant landing of any human-made craft.


 * Juno (spacecraft): NASA space probe orbiting the planet Jupiter; launched from Cape Canaveral Air Force Station 2011.08.05, entered a polar orbit of Jupiter 2016.07.05 (UTC), to begin a scientific investigation of the planet. After completing its mission, Juno will be intentionally deorbited into Jupiter's atmosphere; measure Jupiter's composition, gravity field, magnetic field, and polar magnetosphere. It will also search for clues about how the planet formed, including whether it has a rocky core, the amount of water present within the deep atmosphere, mass distribution, and its deep winds, which can reach speeds of 618 kilometers per hour. Juno is powered only by solar arrays, the three largest solar array wings ever deployed on a planetary probe play an integral role in stabilizing the spacecraft as well as generating power.

Space telescopes

 * Great Observatories program (NASA): four large, powerful space-based astronomical telescopes launched between 1990 and 2003. They were built with different technology to examine specific wavelength/energy regions of the electromagnetic spectrum: gamma rays, X-rays, visible and ultraviolet light, and infrared light.
 * Hubble Space Telescope: space telescope that was launched into low Earth orbit in 1990, and remains in operation.

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 * Planck (spacecraft): space observatory operated by ESA from 2009 to 2013, which mapped the anisotropies of CMB at microwave and infrared frequencies, with high sensitivity and small angular resolution. The mission substantially improved upon observations made by the NASA Wilkinson Microwave Anisotropy Probe (WMAP). Planck provided a major source of information relevant to several cosmological and astrophysical issues, such as testing theories of the early Universe and the origin of cosmic structure. Since the end of its mission, Planck has defined the most precise measurements of several key cosmological parameters, including the average density of ordinary matter and dark matter in the Universe and the age of the universe.
 * Gaia (spacecraft): a space observatory of ESA, launched in 2013 and expected to operate until c. 2022. The spacecraft is designed for astrometry: measuring the positions, distances and motions of stars with unprecedented precision. The mission aims to construct by far the largest and most precise 3D space catalog ever made, totalling approximately 1 billion astronomical objects, mainly stars, but also planets, comets, asteroids and quasars, among others. The Gaia mission will create a precise three-dimensional map of astronomical objects throughout the Milky Way and map their motions, which encode the origin and subsequent evolution of the Milky Way.
 * Kepler (spacecraft): space observatory launched by NASA to discover Earth-like planets orbiting other stars. The spacecraft, named after the Renaissance astronomer Johannes Kepler, was launched on 2009.03.07.

ESA

 * European Space Agency (ESA; French: Agence spatiale européenne, ASE; German: Europäische Weltraumorganisation): intergovernmental organisation of 22 member states dedicated to the exploration of space. Established in 1975 and headquartered in Paris, ESA has a worldwide staff of about 2,200 in 2018 and an annual budget of about €6.5 bln in 2021. ESA's space flight programme includes human spaceflight (mainly through participation in the International Space Station program); the launch and operation of unmanned exploration missions to other planets and the Moon; Earth observation, science and telecommunication; designing launch vehicles; and maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana . The main European launch vehicle Ariane 5 is operated through Arianespace with ESA sharing in the costs of launching and further developing this launch vehicle. The agency is also working with NASA to manufacture the Orion Spacecraft service module that will fly on the Space Launch System.
 * Member states, funding and budget: Membership and contribution to ESA: English is the main language within ESA. Additionally, official documents are also provided in German and documents regarding the Spacelab are also provided in Italian. If found appropriate, the agency may conduct its correspondence in any language of a member state. Non-full member states: Slovenia; Latvia; Lithuania; Canada. Relationship with the European Union: The political perspective of the European Union (EU) was to make ESA an agency of the EU by 2014; however, this date was not met. The EU member states provide most of ESA's funding, and they are all either full ESA members or observers.
 * Cooperation with other countries and organisations: Languages: According to Annex 1, Resolution No. 8 of the ESA Convention and Council Rules of Procedure, English, French and German may be used in all meetings of the Agency, with interpretation provided into these three languages. All official documents are available in English and French with all documents concerning the ESA Council being available in German as well.


 * List of European Space Agency programmes and missions: staple of the ESA's Science Doctrine is the Cosmic Vision programme, a series of space science missions chosen by the ESA to launch through competitions, similar to NASA's Discovery and New Frontiers programmes. It succeeds the Horizon 2000 and Horizon 2000+ programmes which launched notable missions such as Huygens, Rosetta and Gaia. Each space science mission are divided into two categories: "Sun and Solar System", missions studying the Solar System, and "Astrophysics", missions studying interstellar astronomy. A similarly operated programme focused on Earth observation, known as the Living Planet Programme, has launched various "Earth Explorers" such as GOCE and Swarm, which serve many forms of Geoscience individually. A number of missions by the ESA have also launched and operated outside of a canonical programme, as is the case with missions such as Giotto, Ulysses, and Mars Express.

NASA

 * Category:NASA


 * Goddard Space Flight Center (FSFC): major NASA space research laboratory established 1959.05.01 as NASA's first space flight center. GSFC employs approximately 10,000 civil servants and contractors. Largest combined organization of scientists and engineers in USA dedicated to increasing knowledge of the Earth, the Solar System, and the Universe via observations from space. GSFC is a major USA laboratory for developing and operating unmanned scientific spacecraft.
 * Space Network (SN): NASA program that combines space and ground elements to support spacecraft communications in Earth vicinity. The SN Project Office at GSFC manages the SN.
 * Near Earth Network: provides orbital communications support for Near-Earth orbiting customer platforms via various NASA ground stations.


 * Project Gemini: NASA's second human spaceflight program. Conducted between projects Mercury and Apollo, Gemini started in 1961 and concluded in 1966. The Gemini spacecraft carried a two-astronaut crew. Gemini's objective was the development of space travel techniques to support the Apollo mission to land astronauts on the Moon. It performed missions long enough for a trip to the Moon and back, perfected working outside the spacecraft with extra-vehicular activity (EVA), and pioneered the orbital maneuvers necessary to achieve space rendezvous and docking.
 * Gemini 8: sixth crewed spaceflight in NASA's Gemini program, launched 1966.03.16. The mission conducted the first docking of two spacecraft in orbit, but suffered the first critical in-space system failure of a U.S. spacecraft which threatened the lives of the astronauts and required immediate abort of the mission. The crew was returned to Earth safely.


 * Template:Apollo program
 * Apollo program: third human spaceflight program carried out by NASA and the program was responsible for the landing of the first humans on Earth's Moon in 1969.
 * Apollo Guidance Computer (AGC): digital computer produced for the Apollo program that was installed on board each Apollo command module (CM) and Apollo Lunar Module (LM). The AGC provided computation and electronic interfaces for guidance, navigation, and control of the spacecraft. The AGC has a 16-bit word length, with 15 data bits and one parity bit. Most of the software on the AGC is stored in a special read-only memory known as core rope memory, fashioned by weaving wires through and around magnetic cores, though a small amount of read/write core memory is available. Astronauts communicated with the AGC using a numeric display and keyboard called the DSKY (for "display and keyboard", pronounced "DIS-kee").
 * List of Apollo missions: Alphabetical mission types: A, B, C, C', D, E(-), F, G, H, I(-), J.


 * Saturn V: was USA human-rated expendable rocket used by NASA's Apollo and Skylab programs from 1966 until 1973; 3 stages (1st: 2,300,000 kg; 2nd: 480,000 kg; 3rd: 120,800 kg); 13 launches (at the hugest budget of NASA ever)
 * List of Apollo astronauts


 * Space Shuttle: partially reusable low Earth orbital spacecraft system operated from 1981 to 2011 NASA as part of the Space Shuttle program. Five complete Space Shuttle orbiter vehicles were built and flown on a total of 135 missions from 1981 to 2011, launched from the Kennedy Space Center (KSC) in Florida. Operational missions launched numerous satellites, interplanetary probes, and the Hubble Space Telescope (HST).
 * Space Shuttle Challenger disaster: fatal incident in USA' space program that occurred 1986.01.28, when the Space Shuttle Challenger (OV-099) broke apart 73 seconds into its flight, killing all seven crew members aboard. The spacecraft disintegrated over the Atlantic Ocean, off the coast of Cape Canaveral, Florida, at 11:39 a.m. EST (16:39 UTC). The disintegration of the vehicle began after a joint in its right solid rocket booster (SRB) failed at liftoff. The failure was caused by the failure of O-ring seals used in the joint that were not designed to handle the unusually cold conditions that existed at this launch.
 * Space Shuttle Columbia disaster: fatal incident in USA space program that occurred 2003.02.01, when the Space Shuttle Columbia (OV-102) disintegrated as it reentered the atmosphere, killing all seven crew members. During the launch of STS-107, Columbia's 28th mission, a piece of foam insulation broke off from the Space Shuttle external tank and struck the left wing of the orbiter. Similar foam shedding had occurred during previous shuttle launches, causing damage that ranged from minor to nearly catastrophic, but some engineers suspected that the damage to Columbia was more serious. Before reentry, NASA managers had limited the investigation, reasoning that the crew could not have fixed the problem if it had been confirmed. When Columbia reentered the atmosphere of Earth, the damage allowed hot atmospheric gases to penetrate the heat shield and destroy the internal wing structure, which caused the spacecraft to become unstable and break apart.


 * Space Shuttle Solid Rocket Booster: first solid fuel motors to be used for primary propulsion on a vehicle used for human spaceflight and provided the majority of the Space Shuttle's thrust during the first two minutes of flight. After burnout, they were jettisoned and parachuted into the Atlantic Ocean where they were recovered, examined, refurbished, and reused . The SRBs were the most powerful rocket motors ever flown.
 * Shuttle-Derived Launch Vehicle (Shuttle-Derived Vehicle):
 * Constellation program: was a human spaceflight program developed by NASA, the space agency of the United States, from 2005 to 2009. The major goals of the program were "completion of the International Space Station" and a "return to the Moon no later than 2020" with a crewed flight to the planet Mars as the ultimate goal.
 * Space Launch System (SLS): USA Space Shuttle-derived heavy launch vehicle being designed by NASA. The SLS will be the most powerful rocket ever built, with about 20% more thrust than the Saturn V and a comparable payload capacity, putting the SLS into the super heavy-lift launch vehicle class of rockets.
 * Exploration Mission 1: is the first planned flight of the Space Launch System and the second uncrewed test flight of the Orion Multi-Purpose Crew Vehicle. As 2012.04, the launch was projected to occur on 2017.12.17 from Launch Complex 39B at the Kennedy Space Center, and the Orion spacecraft would perform a circumlunar trajectory during the seven day mission.
 * Earth Departure Stage: name given to the second stages of two Shuttle-Derived Launch Vehicles, the Ares V and the Block II Space Launch System.
 * Orion (spacecraft) (Orion Multi-Purpose Crew Vehicle): planned, beyond-low Earth orbit (LEO) manned spacecraft that is being built by Lockheed Martin for NASA, and Astrium for ESA for crewed missions to the Moon, asteroids and Mars.
 * ESA Automated Transfer Vehicle → Orion Service Module


 * Template:Commercial Crew and Cargo
 * Commercial Orbital Transportation Services: was a NASA program to coordinate the delivery of crew and cargo to ISS by private companies. The COTS program was successfully concluded in November 2013 after two companies, SpaceX and Orbital Sciences, designed, built and launched "a pair of new spacecraft on rockets that also were newly designed".
 * Commercial Resupply Services: contracts signed by NASA for the delivery of cargo to ISS by commercial firms; contracts include a minimum of 12 missions for SpaceX and 8 missions for Orbital Sciences.
 * Commercial Crew Development: multiphase space technology development program, funded by the U.S. government, and administered by NASA; program is intended to stimulate development of privately operated crew vehicles to low Earth orbit. The Boeing Company, Sierra Nevada Corporation, SpaceX.


 * Large strategic science missions (formerly Flagship missions): costliest and most capable NASA science spacecraft. Flagship missions exist within all four divisions of NASA's Science Mission Directorate (SMD): the astrophysics, Earth science, heliophysics and planetary science divisions . "Large" refers to the budget of each mission, typically the most expensive mission in the scientific discipline. Within the Astrophysics Division and the Planetary Science Division, the large strategic missions are usually in excess of US$1 billion. Within Earth Science Division and Heliophysics Division, the large strategic missions are usually in excess of US$500 million. "Strategic" refers to their role advancing multiple strategic priorities set forth in plans such as the Decadal Surveys. Flagship missions are always Class A missions: high priority, very low risk.
 * New Frontiers program: series of space exploration missions being conducted by NASA with the purpose of furthering our understanding of the Solar System. The program selects medium-class missions which can provide high science returns. It is designed for medium-class missions that cannot be accomplished within the cost and time constraints of Discovery, but are not as large as Large Strategic Science Missions (Flagship missions).
 * Discovery Program: series of Solar System exploration missions funded by NASA through its Planetary Missions Program Office. Each mission has a cost cap, at a lower level than a mission from NASA's New Frontiers or Flagship Programs. As a result, Discovery missions tend to be more focused on a specific scientific goal (rather than serving a general purpose). The Discovery Program was founded in 1990 to implement then-NASA Administrator Daniel S. Goldin's policy of "faster, better, cheaper" planetary science missions. The Discovery Program also includes Missions of Opportunity, which fund US participation in spacecraft operated by other space agencies (e.g. by contributing a single scientific instrument). It can also be used to re-purpose an existing NASA spacecraft for a new mission.


 * Astronomy and Astrophysics Decadal Survey: review of astronomy and astrophysics literature produced approximately every ten years by the National Research Council of the National Academy of Sciences in USA. The report surveys the current state of the field, identifies research priorities, and makes recommendations for the coming decade. The report represents the recommendations of the research community to governmental agencies on how to prioritize scientific funding within astronomy and astrophysics.
 * Planetary Science Decadal Survey: publication of USA National Research Council produced for NASA and other USA Government Agencies such as NSF. The document identifies key questions facing planetary science and outlines recommendations for space and ground-based exploration ten years into the future. Missions to gather data to answer these big questions are described and prioritized, where appropriate. Similar Decadal Surveys cover Astronomy and Astrophysics, Earth Science and Heliophysics. Various surveys published by the Space Science Board have appeared since 1965 but so far only two "Decadals": in 2002 for the time period 2003 to 2012; in 2011 for 2013 to 2022.


 * China exclusion policy of NASA (2011-): 1999.05 the Report of the Select Committee on U.S. National Security and Military/Commercial Concerns with the People's Republic of China was made public. It alleged that the technical information that American companies provided China for its commercial satellite ended up improving Chinese intercontinental ballistic missile technology.


 * Artemis program: USA-led international human spaceflight program. Its primary goal is to return humans to the Moon, specifically the lunar south pole, by 2025 . If successful, it will include the first crewed lunar landing mission since Apollo 17 in 1972, the last lunar flight of the Apollo program. The Artemis program is carried out predominantly by NASA and USA commercial spaceflight contractors, in partnership with ESA and the space agencies of several other nations. Other countries have been invited to join the program through signing the governing Artemis Accords, which remain open for signature since October 2020.
 * Commercial Lunar Payload Services: NASA program to contract transportation services able to send small robotic landers and rovers to the Moon's south polar region mostly with the goals of scouting for lunar resources, testing in situ resource utilization (ISRU) concepts, and performing lunar science to support the Artemis lunar program. CLPS is intended to buy end-to-end payload services between Earth and the lunar surface using fixed priced contracts. The program was extended to add support for large payloads starting after 2025.

SpaceX

 * Category:SpaceX
 * Category:SpaceX Dragon
 * Category:SpaceX Dragon 2
 * Category:SpaceX satellites
 * Category:SpaceX spacecraft
 * Category:SpaceX Starship


 * Template:SpaceX
 * SpaceX: Elon Musk believes the high prices of other space-launch services are driven in part by unnecessary bureaucracy. He has stated that one of his goals is to improve the cost and reliability of access to space, ultimately by a factor of ten. Besides NASA contracts, SpaceX has signed contracts with private sector companies, non-American government agencies and the American military for its launch services, filling a growing launch manifest.
 * SpaceX reusable launch system development program: privately funded program to develop a set of new technologies for an orbital launch system that may be reused many times in a manner similar to the reusability of aircraft. The project's long-term objectives include returning a launch vehicle first stage to the launch site in minutes and to return a second stage to the launch pad following orbital realignment with the launch site and atmospheric reentry in up to 24 hours . SpaceX's long term goal is that both stages of their orbital launch vehicle will be designed to allow reuse a few hours after return .
 * Key People:
 * Elon Musk (CEO, CTO)
 * Tom Mueller (1961.03.11-): USA aerospace engineer and rocket engine designer. He was a founding employee of SpaceX, USA aerospace manufacturer and space transportation services company headquartered in Hawthorne, California, and the founder and CEO of Impulse Space. He is best known for his engineering work on the TR-106 and several SpaceX rocket engines. He is considered one of the world's leading spacecraft propulsion experts and holds several United States patents for propulsion technology. As Vice President of Propulsion Engineering and subsequently CTO of Propulsion at SpaceX, Mueller led the team that developed the Merlin 1A and Kestrel engines for the Falcon 1, the first liquid fueled orbital rocket launched by a private company; the Merlin 1C, Merlin 1D and MVac engines for the early iterations of the Falcon 9 launch vehicle; as well as the Draco thrusters that provide the attitude control thrusters for the Dragon spacecraft, as well as the SuperDraco storable-propellant engines used to power the capsule launch escape system.
 * Gwynne Shotwell (1963.11.23-): USA businesswoman; President and COO of SpaceX.
 * William H. Gerstenmaier (1954.09.26): aerospace engineer and policymaker who is Vice President, Build and Flight Reliability at SpaceX. He previously served as NASA's Associate Administrator for Human Exploration and Operations between 2005 and July 10, 2019. While in that role, he was described as "arguably the most influential person when it comes to US spaceflight." Prior to being Associate Administrator, Gerstenmaier served as the International Space Station Office Program Manager, at Johnson Space Center, a position he began in June 2002. He spent a total of four decades with NASA.


 * SpaceX Merlin (Propellant: LOX / RP-1; Cycle: Gas-generator): family of rocket engines developed by SpaceX for use on its Falcon 1, Falcon 9 and Falcon Heavy launch vehicles. The Merlin engine was originally designed for sea recovery and reuse, but since 2016 the entire Falcon 9 booster is recovered for reuse by landing vertically on a landing pad using one of its nine Merlin engines . Revisions:
 * Merlin 1A - initial version used an inexpensive, expendable, ablatively cooled carbon-fiber-reinforced polymer composite nozzle and produced 340 kN of thrust.
 * Merlin 1B - turbopump upgrades were handled by Barber-Nichols, Inc. for SpaceX. It was intended for Falcon 1 launch vehicles, capable of producing 380 kN of thrust at sea level and 420 kN in vacuum, and performing with a specific impulse of 261 s (2.56 km/s) at sea level and 303 s (2.97 km/s) in vacuum.
 * Merlin 1C - three versions were produced. The Merlin engine for Falcon 1 had a movable turbopump exhaust assembly, which was used to provide roll control by vectoring the exhaust. The Merlin 1C engine for the Falcon 9 first stage is nearly identical to the variant used for the Falcon 1, although the turbopump exhaust assembly is not movable. Finally, a Merlin 1C vacuum variant is used on the Falcon 9 second stage.
 * Merlin Vacuum (1C)
 * Merlin 1D - developed by SpaceX between 2011 and 2012, with first flight in 2013. The design goals for the new engine included increased reliability, improved performance, and improved manufacturability. In 2011, performance goals for the engine were a vacuum thrust of 690 kN, a vacuum specific impulse (Isp ) of 310 s (3.0 km/s), an expansion ratio of 16 (as opposed to the previous 14.5 of the Merlin 1C) and chamber pressure in the "sweet spot" of 9.7 MPa.
 * Falcon 9 first-stage landing tests: series of controlled-descent flight tests that have been conducted by SpaceX since 2013. The program's objective is to execute a controlled re-entry, descent and landing (EDL) of the Falcon 9 first stage into Earth's atmosphere after it completes the boost phase of an orbital spaceflight. The first tests aimed to touch down vertically in the ocean at zero velocity. Later tests attempted to land the rocket precisely on an autonomous spaceport drone ship (a barge commissioned by SpaceX to provide a stable landing surface at sea) or on terra firma on a ground pad at Cape Canaveral. As of May 2016, twelve test flights have been conducted, four of which achieved a soft landing and recovery of the booster: flight 20 safely touching down on the ground pad upon first attempt in December 2015, flight 23 finally achieving a vertical landing at sea in April 2016 after four previous attempts, and flight 24 and flight 25 returning at higher speed from GTO missions in May 2016.
 * List of Falcon 9 launches


 * Kennedy Space Center Launch Complex 39: rocket launch site at the John F. Kennedy Space Center on Merritt Island in Florida. As of 2016, its launch pads are being modified to support launches of the SpaceX Falcon 9, Dragon 2 and Falcon Heavy, and NASA's Space Launch System, with a new pad, C, added to support smaller launches. 2013.12.13 NASA announced that they had selected SpaceX as the new commercial tenant; SpaceX signed the lease agreement in 2014.04.14 and have been given a twenty-year exclusive lease of Pad 39A.


 * Falcon Heavy: reusable super heavy-lift launch vehicle being designed and manufactured by SpaceX. The Falcon Heavy (previously known as the Falcon 9 Heavy) is a variant of the Falcon 9 launch vehicle and consists of a strengthened Falcon 9 rocket core with two additional Falcon 9 first stages as strap-on boosters.
 * Falcon Heavy Demonstration Mission: Falcon Heavy Test Flight or Falcon Heavy Maiden Flight) was the first attempt by SpaceX to launch a Falcon Heavy rocket, on 6 February 2018 at 20:45 UTC. The launch made spaceflight history by introducing the most powerful rocket currently in operation, twice as powerful as the next most powerful rocket in current operation. It marks the most powerful rocket launched since the retirement of the Saturn V.
 * Elon Musk's Tesla Roadster: private automobile that has been adapted to fit as a dummy payload for the maiden flight of the Falcon Heavy rocket. The car will be launched into an elliptical orbit around the Sun that goes out as far as the orbit of Mars. The first segment of the orbit is similar to a Hohmann transfer orbit to Mars. However, the car is not going to fly by Mars nor enter an orbit around it. Because of the risk involved with the launch of the new rocket, Musk previously stated that he intended to launch the "silliest thing we can imagine" on the new rocket, but the exact payload was not known until the Roadster announcement.


 * Autonomous spaceport drone ship: ocean-going vessel derived from a deck barge, outfitted with station-keeping engines and a large landing platform. Construction of such ships was commissioned by aerospace company SpaceX to allow for recovery of rocket first-stages at sea for high-velocity missions which do not carry enough fuel to return to the launch site after lofting spacecraft onto an orbital trajectory. SpaceX has two operational drone ships: Just Read the Instructions in the Pacific for launches from Vandenberg, and Of Course I Still Love You in the Atlantic for launches from Cape Canaveral. As of 2017.10.30, seventeen Falcon 9 flights have attempted to land on a drone ship, with twelve of them succeeding, the first vertical landing being the CRS-8 mission in 2016.04.


 * SpaceX Dragon (Dragon 1, Cargo Dragon): class of partially reusable cargo spacecraft developed by SpaceX, an American private space transportation company. Dragon was launched into orbit by the company's Falcon 9 launch vehicle to resupply ISS. During its maiden flight in 2010.12, Dragon became the first commercially built and operated spacecraft to be recovered successfully from orbit. 2012.05.25, a cargo variant of Dragon became the first commercial spacecraft to successfully rendezvous with and attach to the ISS. The last flight of the first version of the Dragon spacecraft (Dragon 1) launched 2020.03.07 (UTC); it was a cargo resupply mission (CRS-20) to ISS. This mission was the last mission of SpaceX of the first Commercial Resupply Services (CRS-1) program, and marked the retirement of the Dragon 1 fleet.
 * SpaceX Dragon 2: class of partially reusable spacecraft developed and manufactured by American aerospace manufacturer SpaceX, primarily for flights to ISS. There are two variants: Crew Dragon, a spacecraft capable of ferrying up to seven crew, and Cargo Dragon, an updated replacement for the original Dragon 1. The spacecraft consists of a reuseable space capsule and an expendable trunk module. The spacecraft launches atop a Falcon 9 Block 5 rocket and the capsule returns to Earth via splashdown. Four operational Dragon 2 spacecraft have been manufactured.


 * SpaceX Raptor: family of full-flow staged combustion cycle rocket engines developed and manufactured by SpaceX, for use on the in-development Starship fully reusable launch vehicle. The engine is powered by cryogenic liquid methane and liquid oxygen (LOX), called as 'Methalox'. The Raptor engine has more than twice the thrust of SpaceX's Merlin engine. Raptor is intended to be used in both stages of the two-stage-to-orbit, super-heavy-lift Starship system launch vehicle, which will supersede Falcon 9 and Falcon Heavy. Starship will be used in various applications, including Earth-orbit satellite delivery, deployment of a large portion of SpaceX's own Starlink megaconstellation, and the exploration and colonization of Mars.
 * SpaceX Starship: fully-reusable, two-stage-to-orbit, super heavy-lift launch vehicle under development by SpaceX. The system is composed of a booster stage, named Super Heavy, and a second stage, also referred to as "Starship". The second stage is being designed as a long-duration cargo, and eventually, passenger-carrying spacecraft. The spacecraft will serve as both the second stage and the in-space long-duration orbital spaceship. Engine development started in 2012, and Starship development began in 2016 as a self-funded private spaceflight project. Testing of the second stage Starship began in 2019 as part of an extensive development program to prove out launch-and-landing and iterate on a variety of design details, particularly with respect to the vehicle's atmospheric reentry. All test articles (Starhopper, Mk1, Mk2, Mk3→SN1, SN2-SN6+), have a 9 m-diameter stainless steel hull. 2020.04.26 Starship SN4 became the first full-scale prototype to pass a cryogenic proof test. 2020.05.05 SN4 completed a single engine static fire with one mounted Raptor engine and became the first full Starship tank to pass a Raptor static fire. 2020.08.04 Starship SN5 completed a 150 meter flight test, landing at an adjacent landing site, thus becoming the first full-scale prototype to perform a successful flight test. 2020.12.09 SN8 flew a largely successful 12.5 km flight test, which included the first 3-engine flight test, the first test of the body flaps during its novel "bellyflop" descent, and the first test of the "flip maneuver" landing burn at the end of the free-fall phase.
 * Super Heavy booster: 72 m long, 9 m diameter, gross liftoff mass of 3,680,000 kg; constructed of stainless steel tanks and structure, holding subcooled liquid methane and liquid oxygen (CH₄/LOX) propellants, powered by ~28 Raptor rocket engines that will provide 72,000 kN total liftoff thrust.
 * Starship upper stage: The SpaceX approach is to tackle the hardest problems first, and Musk sees the hardest problem for getting to sustainable human civilization on Mars to be building a fully-reusable orbital Starship, so that is the major focus of SpaceX resources as of 2020. For example, it is planned for the spacecraft to eventually incorporate life support systems, but as of 2019.09, Musk has stated that it is yet to be developed, as the early flights will all be cargo only . Starship upper stage is expected to be a 9 m diameter, 50 m tall, fully reusable spacecraft with a dry mass of 120 t or less, powered by 6 Raptor engines. Starship is designed with the ability to re-enter Earth's atmosphere and retropropulsively land on a designated landing pad. Landing reliability is projected by SpaceX to ultimately be able to achieve "airline levels" of safety due to engine-out capability. The spacecraft is also designed to be able to perform automatic rendezvous and docking operations, and perform on-orbit propellant transfers between Starships . As envisioned in the 2017 design unveiling, the Starship is to have a pressurized volume of approximately 825 m³, which could be configured for up to 40 cabins, large common areas, central storage, a galley, and a solar flare shelter for Mars missions . Modified version known as the Starship Human Landing System (Starship HLS) was selected by NASA in April 2020 for potential use for long-duration crewed lunar landings as part of NASA's Artemis program. The Starship HLS variant is being designed to stay on and around the Moon and as such both the heat shield and air-brakes—integral parts of the main Starship design—are not included in the Starship HLS design.
 * Funding: Elon Musk said that there is no expectation of receiving NASA contracts for any of the ITS system work SpaceX was doing. He also indicated that such contracts, if received, would be good. In 2017, the company settled on a 9 m diameter design and commenced procuring equipment for vehicle manufacturing operations. In late 2018, they switched the design from carbon composite materials for the main structures to stainless steel, further lowering build costs. By late 2019, SpaceX projected that, with company private investment funding, including contractual funds from Yusaku Maezawa who had recently contracted for a private lunar mission in 2023, they have sufficient funds to advance the Earth-orbit and lunar-orbit extent of flight operations, although they may raise additional funds in order "to go to the Moon or landing on Mars".
 * Starship development history: long-duration cargo and, eventually, passenger-carrying spacecraft. The development of the Starship began around 2012. While the Starship program had only a small development team during the early years, and a larger development and build team since late 2018, Musk made Starship the top SpaceX development priority following the first human spaceflight launch of Crew Dragon in May 2020, except for anything related to reduction of crew return risk.
 * Background: Mars Colonial Transporter (MCT).
 * Interplanetary Transport System (ITS): In mid-September 2016, Musk noted that the Mars Colonial Transporter name would not continue, as the system would be able to "go well beyond Mars", and that a new name would be needed. The name selected was ITS, although in an AMA on Reddit 2016.10.23, Musk stated, "I think we need a new name. ITS just isn't working. I'm using BFR and BFS for the rocket and spaceship, which is fine internally, but...", without stating what the new name might be.
 * Big Falcon Rocket (BFR): SpaceX's privately funded next-generation launch vehicle and spacecraft announced by Elon Musk in 2017.09. It includes reusable launch vehicles and spacecraft that are intended by SpaceX to replace all of the company's current hardware by the early 2020s, ground infrastructure for rapid launch and relaunch, and zero-gravity propellant transfer technology to be deployed in LEO. The new vehicles are much larger than the existing SpaceX fleet, and the large payload to LEO of 150,000 kg making it a super heavy-lift launch vehicle. The BFR system is planned to replace both Falcon 9 and Falcon Heavy launch vehicles, as well as the Dragon spacecraft, initially aiming at the Earth-orbit launch market, but explicitly adding substantial capability to support long-duration spaceflight in the cislunar and Mars mission environments. SpaceX intends this approach to bring significant cost savings which will help the company justify the development expense of designing and building the BFR system. SpaceX had initially envisioned a larger design known as the ITS launch vehicle, which was presented in 2016.09 as part of Musk's vision for an interplanetary transport system. The ITS range of vehicles was designed with a 12-meter core diameter, and the BFR design was scaled down to 9 meters. While the ITS had been solely aimed at Mars transit and other interplanetary uses, SpaceX pivoted in 2017 to a plan that would support all SpaceX launch service provider capabilities with a single range of vehicles: Earth-orbit, Lunar-orbit, interplanetary missions, and even intercontinental passenger transport on Earth . Tooling for the main tanks has been ordered and a facility to build the vehicles is under construction; construction of the first ship is scheduled to begin in the second quarter of 2018, with first suborbital flights planned for 2019. The company publicly stated an aspirational goal for initial Mars-bound cargo flights of BFR launching as early as 2022, followed by the first crewed BFR flight one synodic period later, in 2024.
 * Starship and Super Heavy: In 2018.09 announcement of a planned 2023 lunar circumnavigation mission, a private flight called #dearMoon project, Musk showed a redesigned concept for the BFR second stage and spaceship with three rear fins and two front canard fins added for atmospheric entry, replacing the previous delta wing and split flaps shown a year earlier. Prototypes and testing:
 * Starhopper
 * Mk1, Mk2, Mk3, Mk4
 * Starship SN1 (Mk3) and SN2
 * Starship SN3 and SN4
 * Starship SN5 and SN6
 * SN7, SN7.1 pathfinder test tanks
 * Starship SN8
 * Starship SN9
 * Booster BN1
 * SpaceX Starship Integrated Flight Test (2023.04.20): SpaceX launched the first Integrated Flight Test of its Starship rocket. The prototype vehicle was destroyed less than four minutes after lifting off from the SpaceX Starbase in Boca Chica, Texas. The vehicle became the most powerful rocket ever flown, breaking the record which had previously been held by the Soviet N1 rocket for over 50 years. The rocket lifted off at 08:33 CDT (13:33 UTC) from SpaceX's private launch site, Boca Chica, Texas, causing damage to the launch pad and its surrounding infrastructure, which SpaceX said was unexpected, and some debris spread into Boca Chica State Park. Three engines did not start or aborted before liftoff, and several others failed during the flight. The vehicle passed max q and entered supersonic flight, but, due to a lack of thrust or thrust vector control, no attempt was made at stage separation. Starship tumbled and the autonomous flight termination system (AFTS) was activated but did not destroy the vehicle immediately, as was intended.
 * DearMoon project (#dearMoon project): lunar tourism mission and art project conceived and financed by Japanese billionaire Yusaku Maezawa. It will make use of a SpaceX Starship on a private spaceflight flying a single circumlunar trajectory around the Moon. The passengers will be Maezawa, several artists, and one or two crew members. The project was unveiled in 2018.09 and the flight is expected to occur no earlier than 2023.


 * SpaceX Mars transportation infrastructure: in order to facilitate the eventual colonization of Mars. The design includes fully reusable launch vehicles, human-rated spacecraft, on-orbit propellant tankers, rapid-turnaround launch/landing mounts, and local production of rocket fuel on Mars via in situ resource utilization (ISRU). SpaceX' aspirational goal is to put the first humans on Mars by 2024.


 * Starlink: satellite internet constellation being constructed by SpaceX providing satellite Internet access. The constellation will consist of thousands of mass-produced small satellites in LEO, working in combination with ground transceivers. SpaceX plans to sell some of the satellites for military, scientific, or exploratory purposes. Astronomers have raised concerns about the constellations’ effect on ground-based astronomy and how the satellites will add to an already jammed orbital environment. It ignited conversations about the ethics of a single company unilaterally changing the night sky’s appearance.
 * Swarm Technologies: private company building a low Earth orbit satellite constellation for communications with IoT devices using a Store and forward design. Social Capital incubated Swarm, Craft Ventures was an early investor. 2021.07.16, Swarm entered into an agreement to become a direct wholly-owned subsidiary of SpaceX. In-Q-Tel, the venture capital arm of the CIA, lists Swarm Technologies as one of their startups. In 2018, Swarm became the first U.S. company found to have deployed satellites without regulatory approval after an FCC investigation into the startup's launch on an Indian PSLV rocket of its first four picosatellites in January that year. In 2021.02, Swarm announced that its commercial services were now live using 72 commercial satellites providing its global low cost data to customers.

Blue Origin

 * Category:Blue Origin


 * Blue Origin: USA privately funded aerospace manufacturer and spaceflight services company set up by Amazon.com founder Jeff Bezos with its headquarters in Kent, Washington. The company is developing technologies to enable private human access to space with the goal to dramatically lower costs and increase reliability. Blue Origin is employing an incremental approach from suborbital to orbital flight, with each developmental step building on its prior work.
 * New Shepard: reusable launch system is a vertical-takeoff, vertical-landing (VTVL), suborbital manned rocket that is being developed by Blue Origin as a commercial system for suborbital space tourism. On 2015.11.23, after reaching 100.5 km altitude (outer space), the New Shepard booster successfully performed a powered vertical soft landing, the first time a booster rocket had returned from space to make a successful vertical landing. The test program continued in 2016 and 2017 with four additional test flights made with the same vehicle (NS2) in 2016 and the first test flight of the new NS3 vehicle made in 2017. The first crewed test flights are planned for 2018.
 * New Glenn: privately funded orbital launch vehicle in development by Blue Origin. It is expected to make its initial test launch in 2020. Design work on the vehicle began in 2012. The high-level specifications for the vehicle were publicly announced in September 2016. New Glenn is described as a 7-meter-diameter, two- or three-stage rocket. Its first stage will be powered by seven BE-4 engines that are also being designed and manufactured by Blue Origin.

United Launch Alliance (ULA) (50% Boeing Defense, Space & Security; 50% Lockheed Martin Space)

 * Category:United Launch Alliance
 * Category:Lockheed Martin
 * Category:Boeing


 * United Launch Alliance (ULA): USA spacecraft launch service provider that manufactures and operates a number of rocket vehicles that are capable of launching spacecraft into orbits around Earth and to other bodies in the solar system. The company, which is a joint venture between Lockheed Martin Space and Boeing Defense, Space & Security, was formed in December 2006. Launch customers of USA government include DoD, NASA, and other organizations. ULA provides launch services using expendable launch systems Delta IV Heavy and Atlas V, and until 2018 the medium-lift Delta II. The Atlas, Delta IV Heavy and the recently retired Delta IV launch systems have launched payloads including weather, telecommunications, and national security satellites, scientific probes and orbiters. ULA also launches commercial satellites. In 2015.05, ULA stated that it would go out of business unless it won commercial and civil satellite launch orders to offset an expected slump in U.S. military and spy launches. Despite ULA's cost-cutting and restructuring, the cheapest ULA space launch in early 2018 remained the Atlas V 401 at a price of approximately US$109 million. As of 2020, the company is developing the Vulcan Centaur, a successor to the Atlas V that includes some Delta IV technology. As of 2020.06, Vulcan's first flight is scheduled for 2021.07.
 * Launch vehicles and engines:
 * Current fleet: Atlas V; Centaur; Delta IV, Delta IV Heavy variant; Delta Cryogenic Second Stage (family of cryogenic rocket stages used on the Delta III and Delta IV rockets)
 * In development: Vulcan Centaur: Blue Origin's BE-4 engine was selected to power Vulcan's first stage in September 2018 after a competition with the Aerojet Rocketdyne's AR1. The first-stage propellant tanks share the diameter of the Delta IV Common Booster Core but will contain liquid methane and liquid oxygen propellants. Vulcan's upper stage will be the Centaur V, an upgraded variant of the Common Centaur/Centaur III that is currently used on the Atlas V. ULA is working on the 'Sensible Modular Autonomous Return Technology' (SMART) reuse concept. The booster engines, avionics, and thrust structure would be detached as a module from the propellant tanks after booster engine cutoff, with the module descending through the atmosphere under an inflatable heat shield. After parachute deployment, the module would be captured by a helicopter in mid-air. ULA estimated that this would reduce the cost of the first stage propulsion by 90%, and 65% of the total first stage cost.
 * Retired: Delta II


 * Vulcan Centaur: two-stage-to-orbit, heavy-lift launch vehicle that is under development by ULA since 2014 with an initial flight expected in 2022. It is principally designed to meet launch demands for USA government's National Security Space Launch (NSSL) program for use by the United States Space Force and U.S. intelligence agencies for national security satellite launches.


 * Atlas V: expendable launch system and the fifth major version in the Atlas launch vehicle family. It was originally designed by Lockheed Martin, now being operated by ULA. Atlas V is also a major NASA launch vehicle. In 2021.08, ULA announced that Atlas V would be retired, and all 29 remaining launches had been sold.

Boeing:
 * Boeing Starliner: class of two partially reusable spacecraft designed to transport crew to ISS and other low-Earth orbit destinations. It is manufactured by Boeing for its participation in NASA's Commercial Crew Program (CCP). The spacecraft consists of a reusable crew capsule and an expendable service module. As of 2021.11 Starliner has not flown a crewed mission. It is designed to be compatible with the Atlas V, Delta IV, Falcon 9, and Vulcan Centaur launch vehicles.

Airbus

 * EADS (European Aeronautic Defence and Space Company N.V.): global pan-European aerospace and defence corporation and a leading defence and military contractor worldwide.
 * Airbus: aircraft manufacturing subsidiary of EADS. Produces 1/2 of the world's jet airliners. Operates in FR, DE, UK & ES. Final assembly production at: Toulouse, Hamburg, Seville and since 2009 Tianjin (PRC; first Airbus assembly line outside EU).
 * Airbus Military
 * Eurocopter: largest in the industry in terms of revenues and turbine helicopter deliveries; main facilities: Eurocopter Deutschland GmbH in Donauwörth and at Eurocopter España in Albacete.
 * Astrium: aerospace subsidiary of EADS; provides civil and military space systems and services. Astrium Satellites, Space Transportation, Services.
 * Cassidian (till 2010: EADS Defence & Security): defence and security division of the EADS; major provider of global security solutions, lead system integration and aerial, land, naval and joint systems.
 * BAE Systems: British multinational defence, security and aerospace company headquartered in London, United Kingdom and with operations worldwide.


 * Airbus Defence and Space: division of Airbus responsible for defence and aerospace products and services. The division was formed in January 2014 during the corporate restructuring of European Aeronautic Defence and Space (EADS), and comprises the former Airbus Military, Astrium, and Cassidian divisions. It is the world's second-largest space company after Boeing and one of the top ten defence companies in the world.
 * Astrium: aerospace manufacturer subsidiary of EADS that provided civil and military space systems and services from 2006 to 2013. In late 2013 Astrium was merged with Cassidian, the defence division of EADS and Airbus Military to form Airbus Defence and Space.

Virgin Galactic, Virgin Orbit

 * Category:Virgin Galactic


 * Virgin Galactic: USA spaceflight company within the Virgin Group. It is developing commercial spacecraft and aims to provide suborbital spaceflights to space tourists and suborbital launches for space science missions. SpaceShipTwo, Virgin Galactic's suborbital spacecraft, is air launched from beneath a carrier airplane known as White Knight Two. Virgin Galactic's founder, Richard Branson, had originally hoped to see a maiden flight by the end of 2009, but the date was delayed for several years, most seriously by 2014.10 in-flight crash of VSS Enterprise. Branson said Virgin Galactic was "in the best position in the world" to provide rocket-powered, point-to-point 4,800 km/h air travel. Finally, in 2018.12.13, VSS Unity achieved the project's first suborbital space flight, VSS Unity VP-03, with two pilots, reaching an altitude of 82.7 km, and officially entering outer space by US standards. In 2019.02, the project carried three people, including a passenger, on VSS Unity VF-01, with a member of the team floating within the cabin during a spaceflight that reached 89.9 km.


 * Scaled Composites: USA aerospace company founded by Burt Rutan and currently owned by Northrop Grumman. It is located at the Mojave Air and Space Port in Mojave, CA, USA. Founded to develop experimental aircraft, the company now focuses on designing and developing concept craft and prototype fabrication processes for aircraft and other vehicles. It is known for unconventional designs, for its use of non-metal, composite materials, and for winning the Ansari X Prize with its experimental spacecraft SpaceShipOne.
 * Scaled Composites Tier One: Scaled Composites' 1990s–2004 program of suborbital human spaceflight using the reusable spacecraft SpaceShipOne and its launcher White Knight. The craft was designed by Burt Rutan, and the project was funded 20 million US Dollars by Paul Allen. The objective of the project was to develop technology for low-cost routine access to space. SpaceShipOne was not itself intended to carry paying passengers, but was envisioned that there would be commercial spinoffs, initially in space tourism.
 * Scaled Composites White Knight: jet-powered carrier aircraft that was used to launch its companion SpaceShipOne, an experimental spaceplane. The White Knight and SpaceShipOne were designed by Burt Rutan and manufactured by Scaled Composites, a private company founded by Rutan in 1982. On three separate flights in 2004, White Knight conducted SpaceShipOne into flight, and SpaceShipOne then performed a sub-orbital spaceflight, becoming the first private craft to reach space. The White Knight is notable as an example of a mother ship which carried a parasite aircraft into flight, releasing the latter which would then execute a high-altitude flight, or a sub-orbital spaceflight. This flight profile is shared with The High and Mighty One and Balls 8, two modified B-52s which carried the North American X-15 into flight. It is also shared with White Knight Two, a descendant which carries SpaceShipTwo into flight as part of the Virgin Galactic fleet.
 * SpaceShipOne: experimental air-launched rocket-powered aircraft with sub-orbital spaceflight capability at speeds of up to 900 m/s, using a hybrid rocket motor. The design features a unique "feathering" atmospheric reentry system where the rear half of the wing and the twin tail booms folds 70° upward along a hinge running the length of the wing; this increases drag while retaining stability. SpaceShipOne completed the first crewed private spaceflight in 2004. That same year, it won the US$10 million Ansari X Prize and was immediately retired from active service. Its mother ship was named "White Knight". Both craft were developed and flown by Mojave Aerospace Ventures, which was a joint venture between Paul Allen and Scaled Composites, Burt Rutan's aviation company. Allen provided the funding of approximately US$25 million.
 * Scaled Composites White Knight Two (WK2): quadjet cargo aircraft that is used to lift the SpaceShipTwo spacecraft to release altitude. It was developed by Scaled Composites from 2007 to 2010 as the first stage of Tier 1b, a two-stage to suborbital-space crewed launch system. WK2 is based on the successful mothership to SpaceShipOne, White Knight, which itself is based on Proteus.
 * SpaceShipTwo: air-launched suborbital spaceplane type designed for space tourism. It is manufactured by The Spaceship Company, a California-based company owned by Virgin Galactic.


 * The Spaceship Company: British/USA spacecraft manufacturing company that was founded by Burt Rutan and Richard Branson in mid-2005 and was jointly owned by Virgin Group (70%) and Scaled Composites (30%) until 2012 when Virgin Galactic became the sole owner.


 * VMS Eve: carrier mothership for Virgin Galactic and launch platform for SpaceShipTwo-based Virgin SpaceShips.
 * VSS Unity (Virgin Space Ship Unity): SpaceShipTwo-class suborbital rocket-powered crewed spaceplane. It is the second SpaceShipTwo to be built and will be used as part of the Virgin Galactic fleet. It first reached an altitude of more than 80 km in 2018.12.13.


 * VSS Enterprise crash (2014.10.31): when the VSS Enterprise, a SpaceShipTwo experimental spaceflight test vehicle operated by Virgin Galactic, suffered a catastrophic in-flight breakup during a test flight and crashed in the Mojave Desert near Cantil, CA, USA. Co-pilot Michael Alsbury was killed and pilot Peter Siebold was seriously injured. The National Transportation Safety Board later concluded that the breakup was caused by Alsbury's premature unlocking of the air brake device used for atmospheric re-entry. The NTSB said other important factors in the accident were inadequate design safeguards, poor pilot training and lack of rigorous oversight by the FAA. Witnesses reported seeing a parachute before the aircraft crashed. Alsbury was killed in the crash. Siebold survived with serious injuries and was transported to Antelope Valley Hospital in nearby Lancaster . The carrier aircraft, VMS Eve, landed safely. The survival of pilot Peter Siebold also marks the first time in history that anyone has survived the destruction of a spacecraft during a flight when others on board have died . Investigators were initially puzzled about how Siebold managed to get out of the rocket plane and parachute to the ground from an altitude of roughly 15 km, an altitude virtually devoid of oxygen. 2014.11.07, Siebold told investigators that the aircraft broke up around him. He was still strapped into his seat. He released the straps and his parachute later deployed automatically. Siebold was not wearing a pressure suit.


 * Virgin Orbit: company within the Virgin Group which provides launch services for small satellites. 2021.01.17 their LauncherOne successfully reached orbit, and successfully deployed 10 cubesats. The company was formed in 2017 to develop the air-launched LauncherOne rocket, launched from Cosmic Girl; this tandem had previously been a project of Virgin Galactic. Based in Long Beach, California, Virgin Orbit has more than 300 employees led by president Dan Hart, a former vice president of government satellite systems at Boeing.
 * LauncherOne: two-stage orbital launch vehicle developed and flown by Virgin Orbit that began operational flights in 2021, after being in development from 2007 to 2020. It is an air-launched rocket, designed to carry smallsat payloads of up to 300 kg into Sun-synchronous orbit (SSO), following air launch from a carrier aircraft at high altitude. The rocket is carried to the upper atmosphere on a modified Boeing 747-400, named Cosmic Girl, and released over the Pacific Ocean. Initial work on the program was done by Virgin Galactic, another Virgin Group subsidiary, before a separate entity— Virgin Orbit—was formed in 2017 to complete development and operate the launch service provider business as a separate entity from the passenger-carrying Virgin Galactic business. The first successful flight was on 2021.01.17, which delivered a payload of 10 CubeSats to LEO. LauncherOne was the first all liquid-fuelled air-launched orbital rocket. A previous test flight was unsuccessful on 25 May 2020, when the rocket failed to reach space.

CNSA

 * China National Space Administration (CNSA)


 * Long March (rocket family): family of expendable launch system rockets operated by CNSA. Development and design falls under the auspices of the China Academy of Launch Vehicle Technology (CAST). In English, the rockets are abbreviated as LM- for export and CZ- within China, as "Chang Zheng" (长征) means Long March in Chinese pinyin. The rockets are named after the Chinese Red Army's Long March during the Chinese Civil War.
 * Entry into commercial launch market: After USA Space Shuttle Challenger was destroyed in 1986, a growing commercial backlog gave China the chance to enter the international launch market. In 1988.09, USA President Ronald Reagan agreed to allow USA satellites to be launched on Chinese rockets . AsiaSat 1, which had originally been launched by the Space Shuttle and retrieved by another Space Shuttle after a failure, was launched by a Long March 3 in 1990 as the first foreign payload on a Chinese rocket. However, major setbacks occurred in 1992–1996. The Long March 2E was designed with a defective payload fairing, which collapsed when faced with the rocket's excessive vibration. After just seven launches, the Long March 2E destroyed the Optus B2 and Apstar 2 satellites and damaged AsiaSat 2. The Long March 3B also experienced a catastrophic failure in 1996, veering off course shortly after liftoff and crashing into a nearby village. At least 6 people were killed on the ground, and the Intelsat 708 satellite was also destroyed. A Long March 3 also experienced a partial failure in August 1996 during the launch of Chinasat-7.
 * Future development: Long March 9 (LM-9, CZ-9, or Changzheng 9, Chinese: 长征九号) is a Chinese super-heavy carrier rocket concept proposed in 2018 that is currently in study. It is planned for a maximum payload capacity of 140,000 kg to low Earth orbit (LEO), 50,000 kg to trans-lunar injection or 44,000 kg to Mars. Its first flight is expected in 2030 in preparation for a lunar landing sometime in the 2030s; a sample return mission from Mars has been proposed as first major mission.


 * Chinese Lunar Exploration Program (Chang'e Project): ongoing series of robotic Moon missions by CNSA. The program incorporates lunar orbiters, landers, rovers and sample return spacecraft, launched using Long March rockets. Launches and flights are monitored by a Telemetry, Tracking, and Command (TT&C) system, which uses 50 m radio antennas in Beijing and 40 m antennas in Kunming, Shanghai, and Ürümqi to form a 3000 km VLBI antenna. A proprietary ground application system is responsible for downlink data reception.
 * Chang'e 5 (Launch: 2020.11.23 20:30 UTC): fifth lunar exploration mission of the Chinese Lunar Exploration Program, and China's first lunar sample-return mission. Like its predecessors, the spacecraft is named after the Chinese moon goddess Chang'e. International collaboration: ESA has supported the Chang'e 5 mission by providing tracking via ESA's Kourou station located in French Guiana. During the landing phase, ESA used its Maspalomas Station located in the Canary Islands and operated by the Instituto Nacional de Técnica Aeroespacial (INTA) in Spain, to support the tracking efforts.


 * Chinese reusable experimental spacecraft (可重复使用试验航天器): first Chinese reusable spacecraft. It was first launched in 2020.09.04 at 07:30 UTC on a Long March 2F from the Jiuquan Satellite Launch Center, in the Gobi Desert of northwestern China. Unofficial reports indicate that the spacecraft is part of the Shenlong spaceplane, which is claimed to be similar to the Boeing X-37B.

Russian aerospeace companies; Soviet (USSR) space program

 * Soviet space program (Космическая программа СССР): national space program of USSR, conducted in competition with its Cold War adversary USA, known as the Space Race from the mid-1950s until the dissolution of the Soviet Union in 1991. It consisted of the development of expendable launch vehicles, uncrewed artificial satellites starting in 1953, and several human spaceflight programs. Over its 38-year history, the Soviet program achieved the first intercontinental ballistic missile (R-7), first satellite (Sputnik 1), first animal in Earth orbit (the dog Laika on Sputnik 2), first human in space and Earth orbit (Yuri Gagarin on Vostok 1), first woman in space and Earth orbit (Valentina Tereshkova on Vostok 6), first spacewalk (Alexei Leonov on Voskhod 2), first Moon impact (Luna 2), first image of the far side of the Moon (Luna 3) and uncrewed lunar soft landing (Luna 9), first space rover (Lunokhod 1), first sample of lunar soil automatically extracted and brought to Earth (Luna 16), and first space station (Salyut 1). Further notable records included the first interplanetary probes: Venera 1 and Mars 1 to fly by Venus and Mars, respectively, Venera 3 and Mars 2 to impact the respective planet surface, and Venera 7 and Mars 3 to make soft landings on these planets.
 * [[File:The Soviet Union 1964 CPA 3089A souvenir sheet (Soviet Conquest of Space. 1st satellite, 1st pennant on the Moon, 1st view of the Moon far side, 1st man in space, 1st group in space, 1st woman in space) large resolution.jpg|thumb|305px|right|Путь к звёздам прокладывают коммунисты. Почтовый блок СССР 1964 года.]]


 * Buran programme (Буран): Soviet and later Russian reusable spacecraft project that began in 1974 at the Central Aerohydrodynamic Institute in Moscow and was formally suspended in 1993. In addition to being the designation for the whole Soviet/Russian reusable spacecraft project, Buran was also the name given to Orbiter K1, which completed one uncrewed spaceflight in 1988 and was the only Soviet reusable spacecraft to be launched into space. The Buran-class orbiters used the expendable Energia rocket as a launch vehicle.


 * Lavochkin (НПО Лавочкина, OKB-301): Russian aerospace company. It is a major player in the Russian space program, being the developer and manufacturer of the Fregat upper stage, as well as interplanetary probes such as Fobos-Grunt.
 * Fregat (Фрегат): upper stage developed by NPO Lavochkin in the 1990s, which is used in some Soyuz and Zenit launch vehicles, but is universal and can be used as a part of a medium and heavy class launch vehicles. Fregat became operational in February 2000. Its liquid propellant engine uses UDMH and N₂O₄. Fregat's success rate is 97.8% (with 2 failures in 90 launches), which makes it one of the most reliable upper stages in the world. It remains the only upper stage in the world that can place its payload into 3 or more different orbits in a single launch.

Life in space

 * Category:Life in space
 * Category:Space farming
 * Category:Space colonization literature


 * Islands in the Sky: Bold New Ideas for Colonizing Space (Stanley Schmidt and Robert Zubrin, eds., Wiley, 1996, ISBN 0-471-13561-5): book composed of a collection of factual articles on space colonization, several from recognized experts in the field. The articles range from colloquial to fairly technical, occasionally deriving results after a series of calculus equations. Their subject matter ranges from colonization of the inner Solar System to the outer Solar System and interstellar colonization, and from novel application of well-understood engineering principles, to speculative physics theories.


 * Plants in space: In the late 20th and 21st century, plants were often taken into space in low Earth orbit to be grown in a weightless but pressurized controlled environment, sometimes called space gardens. In the context of human spaceflight, they can be consumed as food and/or provide a refreshing atmosphere. To date plants taken into space have had mostly scientific interest, with only limited contributions to the functionality of the spacecraft. The first challenge in growing plants in space is how to get plants to grow without gravity. This runs into difficulties regarding the effects of gravity on root development, providing appropriate types of lighting, and other challenges. In 2018.12 the German Aerospace Center launched the EuCROPIS satellite into low Earth orbit. This mission carries two greenhouses intended to grow tomatoes under simulated gravities of the Moon and Mars using by-products of human presence in space as source of nutrients.
 * EuCROPIS (Eu:CROPIS (Euglena and Combined Regenerative Organic-Food Production in Space)): life science satellite developed by the German Aerospace Center (DLR) and is intended to investigate the possibility of growing plants (specifically tomatoes) in different levels of gravity, such as on the Moon and Mars, as a sustainable food source while using human urine for moisture and as the source of fixed nitrogen.


 * Space farming: cultivation of crops for food and other materials in space or on off-Earth celestial objects – equivalent to agriculture on Earth. Farming on celestial bodies, such as the Moon or Mars, shares many similarities with farming on a space station or space colony. But, depending on the size of the celestial body, may lack the complexity of microgravity found in the latter. The supply of food to space stations and other long duration missions is heavy and staggeringly expensive. One astronaut on ISS requires approximately "1.8 kg of food and packaging per day". For a long-term mission, such as a four-man crew, three year Martian mission, this number can grow to as much as 10.9 t. In addition to maintaining a shelf-life and reducing total mass, the ability to grow food in space would help reduce the vitamin gap in astronaut's diets and provide fresh food with improved taste and texture . Currently, much of the food supplied to astronauts is heat treated or freeze dried. Both of these methods, for the most part, retain the properties of the food pre-treatment. However, vitamin degradation during storage can occur. A 2009 study noted significant decreases in vitamins A, C and K as well as folic acid and thiamin can occur in as little as one year of storage. Supply of foodstuffs to others is likely to be a major part of early off-Earth settlements. Food production is a non-trivial task and is likely to be one of the most labor-intensive, and vital, tasks of early colonists. Technical challenges: reduced gravity, lighting, and pressure as well as increased radiation. However, a 2006 study (10.1089/ast.2006.6.851) suggests maintaining elevated CO2 concentrations can mitigate the effects of hypobaric conditions as low as 10 kPa to achieve normal plant growth. Martian soil contains a majority of the minerals needed for plant growth except for reactive nitrogen, which is a product of mineralization of organic matter. Since there is a lack of organic matter on the surface of mars, there is a lack of this component. Reactive nitrogen is a required constituent of soil used for plant growth, and it is possible that nitrogen fixing species, such as bacteria, could aide in the lack of reactive nitrogen series. However, a 2014 study (10.1371/journal.pone.0103138) suggested that plants were able to germinate and survive a period of 50 days on a Martian and lunar soil by using simulant soils. This being said, only one of their four experimented species did well enough to achieve full flower formation and more work would need to be done to achieve complete growth. Crops experimented with: potatoes, grains, rice, beans, tomatoes, paprika, lettuce, cabbage, strawberry, onions and peppers.

People who have been in space, human psychology in space

 * Category:American astronauts

Space is hard on humans, training for space mission are hard, loneliness, small cramped space. For the future, being on the Moon or Mars means communication with Earth delays, in Mars case between 10 and 20 min.


 * Space adaptation syndrome (SAS; space sickness): condition experienced by as many as half of all space travelers during their adaptation to weightlessness once in orbit. It is the opposite of terrestrial motion sickness since it occurs when the environment and the person appear visually to be in motion relative to one another even though there is no corresponding sensation of bodily movement originating from the vestibular system.
 * Steven Smith: "Your body just isn't built to deal with zero-gravity. But there's no way of predicting how someone will handle it. Someone who gets car-sick all the time can be fine in space - or the opposite. I'm fine in cars and on rollercoasters, but space is a different matter." This theory is also known as neural mismatch, implying a mismatch occurring between ongoing sensory experience and long-term memory rather than between components of the vestibular and visual systems, emphasizing "the limbic system in integration of sensory information and long-term memory, in the expression of the symptoms of motion sickness, and the impact of anti-motion-sickness drugs and stress hormones on limbic system function. The limbic system may be the neural mismatch center of the brain." At present a "fully adequate theory of motion sickness is not presently available" but at present the sensory conflict theory, referring to "a discontinuity between either visual, proprioceptive, and somatosensory input, or semicircular canal and otolith input", may be the best available.
 * History: In 1961.08, Soviet cosmonaut Gherman Titov became the first human to experience space sickness on Vostok 2; he was the first person to vomit in space. Apart from that record, space motion sickness was effectively unknown during the earliest spaceflights (Mercury, Gemini series) probably because these missions were undertaken in spacecraft providing very cramped conditions and permitting very little room for head movements; space sickness seems to be aggravated by being able to freely move around, especially in regard to head movement, and so is more common in larger spacecraft.


 * Lisa Nowak (née Caputo, 1963.05.10-): USA aeronautical engineer, and former NASA astronaut and US Navy captain. Nowak served as naval flight officer and test pilot in the Navy, and was selected by NASA for NASA Astronaut Group 16 in 1996, qualifying as a mission specialist in robotics. She flew in space aboard Space Shuttle Discovery during the STS-121 mission in July 2006, when she was responsible for operating the robotic arms of the shuttle and the International Space Station. In 2007, Nowak was involved in an incident that led to her dismissal from NASA and the Navy. Orlando Airport incident: According to documents submitted by her lawyer, Nowak was evaluated by two psychiatrists who diagnosed her with obsessive–compulsive personality disorder, Asperger syndrome, a single episode of major depressive disorder and a "brief psychotic disorder with marked stressors" at the time of the incident.

Human spaceflight analogs

 * Category:Human analog missions


 * MARS-500: psychosocial isolation experiment conducted between 2007 and 2011 by Russia, ESA and China, in preparation for an unspecified future crewed spaceflight to the planet Mars. The experiment's facility was located at the Russian Academy of Sciences' Institute of Biomedical Problems (IBMP) in Moscow. Between 2007 and 2011, three different crews of volunteers lived and worked in a mock-up spacecraft at IBMP. The final stage of the experiment, which was intended to simulate a 520-day crewed mission, was conducted by an all-male crew consisting of three Russians (Alexey Sitev, Sukhrob Kamolov, Alexander Smoleevskij), a Frenchman (Romain Charles), an Italian (Diego Urbina) and a Chinese citizen (Yue Wang). The mock-up facility simulated an Earth-Mars shuttle spacecraft, an ascent-descent craft, and the Martian surface. The volunteers who participated in the three stages included professionals with experience in engineering, medicine, biology, and human spaceflight. The experiment yielded important data on the physiological, social and psychological effects of long-term close-quarters isolation.

Spacecraft components

 * Category:Spacecraft components


 * Airlock: device which permits the passage of people and objects between a pressure vessel and its surroundings while minimizing the change of pressure in the vessel and loss of air from it. The lock consists of a small chamber with two airtight doors in series which do not open simultaneously. An airlock may be used for passage between environments of different gases rather than different pressures, to minimize or prevent the gases from mixing. An airlock may also be used underwater to allow passage between an air environment in a pressure vessel and the water environment outside, in which case the airlock can contain air or water. This is called a floodable airlock or an underwater airlock, and is used to prevent water from entering a submersible vessel or an underwater habitat. Applications: spacecraft & space stations; hyperbaric chambers; submarines, diving chambers & underwater habitats; torpedo tubes & escape trunks; cleanrooms; hazardous environments; electron microscopes; parachute airlocks; fermentation vessels.


 * Suitport (suitlock): alternative technology to an airlock, designed for use in hazardous environments and in human spaceflight, especially planetary surface exploration. Suitports present advantages over traditional airlocks in terms of mass, volume, and ability to mitigate contamination by—and of—the local environment.

Galaxies

 * Category:Extragalactic astronomy
 * Category:Large-scale structure of the cosmos
 * Category:Galaxies
 * Category:Active galaxies
 * Category:Quasars


 * Active galactic nucleus (AGN): compact region at the centre of a galaxy that has a much higher than normal luminosity over at least some portion, and possibly all, of the electromagnetic spectrum. Such excess emission has been observed in the radio, microwaves, infrared, optical, ultra-violet, X-ray and gamma ray wavebands. A galaxy hosting an AGN is called an active galaxy. The radiation from AGN is believed to be a result of accretion of mass by a supermassive black hole at the centre of its host galaxy. AGN are the most luminous and persistent sources of electromagnetic radiation in the universe, and as such can be used as a means of discovering distant objects; their evolution as a function of cosmic time also puts constraints on models of the cosmos.
 * Quasar (quasi-stellar radio sources): the most energetic and distant members of a class of objects called active galactic nuclei. Quasars are extremely luminous and were first identified as being high redshift sources of electromagnetic energy, including radio waves and visible light, that appeared to be similar to stars, rather than extended sources similar to galaxies. Their luminosity can be 100 times greater than that of the Milky Way. Scientific consensus that a quasar is a compact region in the center of a massive galaxy, that surrounds its central supermassive black hole. Its size is 10–10,000 times the Schwarzschild radius of the black hole. The energy emitted by a quasar derives from mass falling onto the accretion disc around the black hole.
 * Blazar: AGN with a relativistic jet that is pointing in the general direction of the Earth. We observe "down" the jet, or nearly so, and this accounts for the rapid variability and compact features of both types of blazars. Many blazars have apparent superluminal features within the first few parsecs of their jets, probably due to relativistic shock fronts.
 * Supermassive black hole: largest type of black hole, with mass on the order of millions to billions of times the mass of the Sun . Observational evidence indicates that almost every large galaxy has a supermassive black hole at the galaxy's center. Accretion of interstellar gas onto supermassive black holes is the process responsible for powering active galactic nuclei and quasars.
 * Sagittarius A* (pronounced "Sagittarius A-Star", abbreviated Sgr A*): bright and very compact astronomical radio source at the Galactic Center of the Milky Way. It is located near the border of the constellations Sagittarius and Scorpius, about 5.6° south of the ecliptic, visually close to the Butterfly Cluster (M6) and Shaula. Sagittarius A* is the location of a supermassive black hole, similar to massive objects at the centers of most, if not all, spiral and elliptical galaxies. Observations of several stars orbiting Sagittarius A*, particularly star S2, have been used to determine the mass and upper limits on the radius of the object. Based on mass and increasingly precise radius limits, astronomers have concluded that Sagittarius A* is the Milky Way's central supermassive black hole. The conjectured mass is slightly in excess of 4 mln. solar masses.
 * S2 (star): located close to the radio source Sagittarius A*, orbiting it with an orbital period of 15.56 ± 0.35 years and a pericenter distance of 17 light hours (18 Tm or 120 AU)—an orbit with a period only about 30% longer than that of Jupiter around the Sun, but coming no closer than about four times the distance of Neptune from the Sun. As of 2002, its mass was initially estimated by the European Southern Observatory (ESO) to be approximately 15 M☉.
 * S0–102: star that is located very close to the centre of the Milky Way, near the radio source Sagittarius A*, orbiting it with an orbital period of 11.5 years. As of 2012 it is the star with the shortest known period orbiting the black hole at the centre of the Milky Way. This beat the record of 15 years previously set by S0–2. At its periapsis, its speed exceeds 1% of the speed of light. At that point it is 260 astronomical units (36 light hours, 38.9 billion km) from the centre, while the black hole radius is less than one thousandth of that size (11 million km). It passed that point in 2009 and will be there again in 2020.


 * Galactic halo: extended, roughly spherical component of a galaxy which extends beyond the main, visible component; stellar halo, galactic corona (hot gas, i.e. a plasma), dark matter halo.


 * Andromeda–Milky Way collision: galaxy collision predicted to occur in about 4 billion years between the two largest galaxies in the Local Group—the Milky Way and the Andromeda Galaxy although the stars involved are sufficiently far apart that it is improbable that any of them will individually collide.

Milky Way

 * Category:Milky Way


 * Milky Way: galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye. The term Milky Way is a translation of the Latin via lactea, from the Greek γαλακτικός κύκλος (galaktikos kýklos), meaning "milky circle." From Earth, the Milky Way appears as a band because its disk-shaped structure is viewed from within. Galileo Galilei first resolved the band of light into individual stars with his telescope in 1610. Until the early 1920s, most astronomers thought that the Milky Way contained all the stars in the Universe. Following the 1920 Great Debate between the astronomers Harlow Shapley and Heber Curtis, observations by Edwin Hubble showed that the Milky Way is just one of many galaxies. The Milky Way is a barred spiral galaxy with an estimated visible diameter of 100,000–200,000 light-years. Recent simulations suggest that a dark matter disk, also containing some visible stars, may extend up to a diameter of almost 2 mln. light-years. The Milky Way has several satellite galaxies and is part of the Local Group of galaxies, which form part of the Virgo Supercluster, which is itself a component of the Laniakea Supercluster. Estimated to contain 100–400 billion stars and at least that number of planets. The Solar System is located at a radius of about 27,000 light-years from the Galactic Center, on the inner edge of the Orion Arm, one of the spiral-shaped concentrations of gas and dust. The stars in the innermost 10,000 light-years form a bulge and one or more bars that radiate from the bulge. The galactic center is an intense radio source known as Sagittarius A* (↑), a supermassive black hole of 4.100 (± 0.034) million solar masses. Stars and gases at a wide range of distances from the Galactic Center orbit at approximately 220 km/s. The constant rotation speed contradicts the laws of Keplerian dynamics and suggests that much (about 90%) of the mass of the Milky Way is invisible to telescopes, neither emitting nor absorbing electromagnetic radiation. This conjectural mass has been termed "dark matter" . The rotational period is about 240 mln. years at the radius of the Sun. The Milky Way as a whole is moving at a velocity of approximately 600 km/s with respect to extragalactic frames of reference. The oldest stars in the Milky Way are nearly as old as the Universe itself and thus probably formed shortly after the Dark Ages of the Big Bang.
 * Satellite galaxies of the Milky Way: 59 small galaxies confirmed to be within 420 kiloparsecs (1.4 mln. light-years) of the Milky Way, but not all of them are necessarily in orbit, and some may themselves be in orbit of other satellite galaxies. The only ones visible to the naked eye are the Large and Small Magellanic Clouds, which have been observed since prehistory. Measurements with the Hubble Space Telescope in 2006 suggest the Magellanic Clouds may be moving too fast to be orbiting the Milky Way. Of the galaxies confirmed to be in orbit, the largest is the Sagittarius Dwarf Elliptical Galaxy, which has a diameter of 2.6 kiloparsecs (8,500 ly) or roughly a twentieth that of the Milky Way.


 * Galactic Center: rotational center, the barycenter, of the Milky Way galaxy. Its central massive object is a supermassive black hole of about 4 million solar masses, which is called Sagittarius A*, a compact radio source which is almost exactly at the galactic rotational center. The Galactic Center is approximately 8 kiloparsecs (26,000 ly) away from Earth in the direction of the constellations Sagittarius, Ophiuchus, and Scorpius, where the Milky Way appears brightest, visually close to the Butterfly Cluster (M6) or the star Shaula, south to the Pipe Nebula. There are around 10 million stars within one parsec of the Galactic Center, dominated by red giants, with a significant population of massive supergiants and Wolf–Rayet stars from star formation in the region around 1 million years ago. The core stars are a small part within the much wider galactic bulge.

Stars, Stellar astronomy

 * Category:Stars
 * Category:Compact stars
 * Category:Star clusters
 * Category:Stellar astronomy
 * Category:Stellar astronomy classification systems
 * Category:Hertzsprung–Russell classifications


 * Stellar population: during 1944, Walter Baade categorized groups of stars within the Milky Way into stellar populations. In the abstract of the article by Baade, he recognizes that Jan Oort originally conceived this type of classification in 1926: "[...] The two types of stellar populations had been recognized among the stars of our own galaxy by Oort as early as 1926". Baade noticed that bluer stars were strongly associated with the spiral arms and yellow stars dominated near the central galactic bulge and within globular star clusters. Two main divisions were defined as Population I and Population II, with another newer division called Population III added in 1978, which are often simply abbreviated as Pop I, II or III. The first stars in the universe (very low metal content) were deemed Population III, old stars (low metallicity) as Population II, and recent stars (high metallicity) as Population I. The Sun is considered population I, a recent star with a relatively high 1.4% metallicity . Note that astrophysics nomenclature considers any element heavier than helium to be a "metal", including chemical non-metals such as oxygen.


 * Compact star (compact object): used to refer collectively to white dwarfs, neutron stars, other exotic dense stars, and black holes.
 * Supernova (SN): sudden reignition of nuclear fusion in a degenerate star (white dwarf) or the collapse of the core of a massive star.


 * Star cluster: large groups of stars. Two types of star clusters can be distinguished: globular clusters are tight groups of hundreds to millions of old stars which are gravitationally bound, while open clusters, more loosely clustered groups of stars, generally contain fewer than a few hundred members, and are often very young.
 * Globular cluster: spherical collection of stars that orbits a galactic core. Globular clusters are very tightly bound by gravity, which gives them their spherical shapes, and relatively high stellar densities toward their centers. The name of this category of star cluster is derived from the Latin, globulus—a small sphere. Globular clusters are found in the halo of a galaxy. Globular clusters are older than, and contain considerably more stars than, the less dense open clusters, which are found in the disk of a galaxy. Globular clusters are fairly common; there are about 150 to 158 currently known globular clusters in the Milky Way, with perhaps 10 to 20 more still undiscovered.


 * Stellar collision: coming together of two stars caused by stellar dynamics within a star cluster, or by the orbital decay of a binary star due to stellar mass loss or gravitational radiation, or by other mechanisms not yet well understood. Astronomers predict that events of this type occur in the globular clusters of our galaxy about once every 10,000 years.
 * Neutron star merger: type of stellar collision. It occurs in a fashion similar to the rare brand of type Ia supernovae resulting from merging white dwarfs. When two neutron stars orbit each other closely, they gradually spiral inward due to gravitational radiation. When the two neutron stars meet, their merger leads to the formation of either a more massive neutron star, or a black hole (depending on whether the mass of the remnant exceeds the Tolman–Oppenheimer–Volkoff limit). The merger can also create a magnetic field that is trillions of times stronger than that of Earth in a matter of one or two milliseconds. These events are believed to create short gamma-ray bursts. The merger of binary neutron stars is believed to be the origin of most elements with large atomic weights - the r-process elements.


 * Hertzsprung–Russell diagram (H–R diagram, HR diagram, HRD): scatter plot of stars showing the relationship between the stars' absolute magnitudes or luminosities versus their stellar classifications or effective temperatures.


 * Evolutionary track 1m.svg


 * Stellar classification: classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the rainbow of colors interspersed with spectral lines. Each line indicates a particular chemical element or molecule, with the line strength indicating the abundance of that element. The strengths of the different spectral lines vary mainly due to the temperature of the photosphere, although in some cases there are true abundance differences. The spectral class of a star is a short code primarily summarizing the ionization state, giving an objective measure of the photosphere's temperature. Most stars are currently classified under the Morgan–Keenan (MK) system using the letters O, B, A, F, G, K, and M, a sequence from the hottest (O type) to the coolest (M type). Each letter class is then subdivided using a numeric digit with 0 being hottest and 9 being coolest (e.g., A8, A9, F0, and F1 form a sequence from hotter to cooler). The sequence has been expanded with classes for other stars and star-like objects that do not fit in the classical system, such as class D for white dwarfs and classes S and C for carbon stars.


 * Stellar nucleosynthesis: creation (nucleosynthesis) of chemical elements by nuclear fusion reactions within stars. Stellar nucleosynthesis has occurred since the original creation of hydrogen, helium and lithium during the Big Bang. As a predictive theory, it yields accurate estimates of the observed abundances of the elements. It explains why the observed abundances of elements change over time and why some elements and their isotopes are much more abundant than others. The theory was initially proposed by Fred Hoyle in 1946, who later refined it in 1954. Further advances were made, especially to nucleosynthesis by neutron capture of the elements heavier than iron, by Margaret and Geoffrey Burbidge, William Alfred Fowler and Hoyle in their famous 1957 B2FH paper, which became one of the most heavily cited papers in astrophysics history.
 * Proton–proton chain (p–p chain): one of two known sets of nuclear fusion reactions by which stars convert hydrogen to helium. It dominates in stars with masses less than or equal to that of the Sun, whereas the CNO cycle, the other known reaction, is suggested by theoretical models to dominate in stars with masses greater than about 1.3 times that of the Sun.
 * CNO cycle (carbon-nitrogen-oxygen): one of the two known sets of fusion reactions by which stars convert hydrogen to helium, the other being the proton–proton chain reaction (p-p cycle), which is more efficient at the Sun's core temperature. The CNO cycle is hypothesized to be dominant in stars that are more than 1.3 times as massive as the Sun.
 * Triple-alpha process
 * Alpha process and alpha process elements (alpha elements)

Celestial mechanics, orbits

 * Category:Celestial mechanics
 * Category:Orbits
 * Category:Astrodynamics
 * Category:Orbits


 * Tidal acceleration: effect of the tidal forces between an orbiting natural satellite (e.g. the Moon) and the primary planet that it orbits (e.g. Earth). The acceleration causes a gradual recession of a satellite in a prograde orbit away from the primary, and a corresponding slowdown of the primary's rotation. The process eventually leads to tidal locking, usually of the smaller body first, and later the larger body (e.g. theoretically with Earth in 50 billion years). The Earth–Moon system is the best-studied case. The similar process of tidal deceleration occurs for satellites that have an orbital period that is shorter than the primary's rotational period, or that orbit in a retrograde direction. The naming is somewhat confusing, because the average speed of the satellite relative to the body it orbits is decreased as a result of tidal acceleration, and increased as a result of tidal deceleration.
 * Tidal locking: between a pair of co-orbiting astronomical bodies occurs when one of the objects reaches a state where there is no longer any net change in its rotation rate over the course of a complete orbit. In the case where a tidally locked body possesses synchronous rotation, the object takes just as long to rotate around its own axis as it does to revolve around its partner. For example, the same side of the Moon always faces the Earth, although there is some variability because the Moon's orbit is not perfectly circular. Usually, only the satellite is tidally locked to the larger body.


 * Delta-v budget: estimate of the total change in velocity (delta-v) required for a space mission. It is calculated as the sum of the delta-v required to perform each propulsive maneuver needed during the mission. As input to the Tsiolkovsky rocket equation, it determines how much propellant is required for a vehicle of given empty mass and propulsion system. Delta-v is a scalar quantity dependent only on the desired trajectory and not on the mass of the space vehicle . For example, although more fuel is needed to transfer a heavier communication satellite from low Earth orbit to geosynchronous orbit than for a lighter one, the delta-v required is the same. Delta-v is also additive, as contrasted to rocket burn time, the latter having greater effect later in the mission when more fuel has been used up. Tables of the delta-v required to move between different space regime are useful in the conceptual planning of space missions. In the absence of an atmosphere, the delta-v is typically the same for changes in orbit in either direction ; in particular, gaining and losing speed cost an equal effort. An atmosphere can be used to slow a spacecraft by aerobraking. Because the delta-v needed to achieve the mission usually varies with the relative position of the gravitating bodies, launch windows are often calculated from porkchop plots that show delta-v plotted against the launch time.


 * Hohmann transfer orbit: orbital maneuver used to transfer a spacecraft between two orbits of different altitudes around a central body. Examples would be used for travel between low Earth orbit and the Moon, or another solar planet or asteroid. In the idealized case, the initial and target orbits are both circular and coplanar. The maneuver is accomplished by placing the craft into an elliptical transfer orbit that is tangential to both the initial and target orbits. The maneuver uses two impulsive engine burns: the first establishes the transfer orbit, and the second adjusts the orbit to match the target. The Hohmann maneuver often uses the lowest possible amount of impulse (which consumes a proportional amount of delta-v, and hence propellant) to accomplish the transfer, but requires a relatively longer travel time than higher-impulse transfers. In some cases where one orbit is much larger than the other, a bi-elliptic transfer can use even less impulse, at the cost of even greater travel time.
 * Interplanetary Transport Network: collection of gravitationally determined pathways through the Solar System that require very little energy for an object to follow. The ITN makes particular use of Lagrange points as locations where trajectories through space can be redirected using little or no energy. These points have the peculiar property of allowing objects to orbit around them, despite lacking an object to orbit. While it would use little energy, transport along the network would take a long time.

Solar System

 * Category:Local Bubble
 * Category:Local Interstellar Cloud
 * Category:Solar System
 * Category:Dynamics of the Solar System


 * List of Solar System objects by size


 * Solar System (solar system): gravitationally bound system of the Sun and the objects that orbit it, either directly or indirectly. Of the objects that orbit the Sun directly, the largest are the eight planets, with the remainder being smaller objects, the dwarf planets and small Solar System bodies. Of the objects that orbit the Sun indirectly—the natural satellites—two are larger than the smallest planet, Mercury (Ganymede and Titan). The Solar System formed 4.6 billion years ago from the gravitational collapse of a giant interstellar molecular cloud. The vast majority of the system's mass is in the Sun, with the majority of the remaining mass contained in Jupiter. The four smaller inner system planets, Mercury, Venus, Earth and Mars, are terrestrial planets, being primarily composed of rock and metal. The four outer system planets are giant planets, being substantially more massive than the terrestrials. The two largest planets, Jupiter and Saturn, are gas giants, being composed mainly of hydrogen and helium; the two outermost planets, Uranus and Neptune, are ice giants, being composed mostly of substances with relatively high melting points compared with hydrogen and helium, called volatiles, such as water, ammonia and methane. All eight planets have almost circular orbits that lie within a nearly flat disc called the ecliptic.
 * Stability of the Solar System: Though the planets have been stable historically, and will be in the short term, their weak gravitational effects on one another can add up in unpredictable ways. For this reason (among others) the Solar System is stated to be chaotic, and even the most precise long-term models for the orbital motion of the Solar System are not valid over more than a few tens of millions of years.




 * "Clearing the neighbourhood around its orbit": criterion for a celestial body to be considered a planet in the Solar System.


 * Orbital resonance: occurs when two orbiting bodies exert a regular, periodic gravitational influence on each other, usually due to their orbital periods being related by a ratio of two small integers. . Orbital resonances greatly enhance the mutual gravitational influence of the bodies, i.e., their ability to alter or constrain each other's orbits. In most cases, this results in an unstable interaction, in which the bodies exchange momentum and shift orbits until the resonance no longer exists (e.g. gaps in the rings of Saturn). Under some circumstances, a resonant system can be stable and self-correcting, so that the bodies remain in resonance.


 * Lagrange point (Lagrangian points, L-points): 5 positions in an orbital configuration where a small object affected only by gravity can theoretically be part of a constant-shape pattern with two larger objects. The Lagrange points mark positions where the combined gravitational pull of the two large masses provides precisely the centripetal force required to orbit with them. Leonhard Euler discovered 3 collinear L-points (L1, L2, L3), while Joseph-Louis Lagrange discovered the remaining two.
 * Lissajous orbit: quasi-periodic orbital trajectory that an object can follow around a Lagrangian point of a three-body system without requiring any propulsion.
 * Co-orbital configuration: refers to two or more celestial objects (such as asteroids, moons, or planets) that orbit at the same, or very similar, distance from their parent object as each other, i.e. they are in a 1:1 mean motion resonance.
 * Trojan (astronomy)
 * Hilda family
 * Halo orbit: periodic, three-dimensional orbit near one of the L1, L2 or L3 Lagrange points in the three-body problem of orbital mechanics. Although a Lagrange point is just a point in empty space, its peculiar characteristic is that it can be orbited. Halo orbits can be thought of as resulting from an interaction between the gravitational pull of the two planetary bodies and the Coriolis and centripetal acceleration on a spacecraft.
 * Weak stability boundary (WSB): including low-energy transfer, a concept introduced by Edward Belbruno in 1987. The concept explained how a spacecraft could change orbits using very little fuel. Weak stability boundary is defined for the three-body problem. This problem considers the motion of a particle P of negligible mass moving with respect to two larger bodies, P1, P2, modeled as point masses, where these bodies move in circular or elliptical orbits with respect to each other, and P2 is smaller than P1. The weak stability boundary defines a region about P2 where P is temporarily captured. This region is in position-velocity space. Capture means that the Kepler energy between P and P2 is negative. This is also called weak capture.


 * Space weather: branch of space physics and aeronomy, or heliophysics, concerned with the time varying conditions within the Solar System, including the solar wind, emphasizing the space surrounding the Earth, including conditions in the magnetosphere, ionosphere, thermosphere, and exosphere.
 * Space Weather Prediction Center (SWPC): laboratory and service center of the US National Weather Service (NWS), part of NOAA, located in Boulder, Colorado. SWPC continually monitors and forecasts Earth's space environment, providing solar-terrestrial information. SWPC is the official source of space weather alerts and warnings for USA.


 * Gas giant: large planet that is not primarily composed of rock or other solid matter. In the Solar System: Jupiter, Saturn, Uranus and Neptune.
 * Ice giant: type of giant planet composed largely of materials less volatile than hydrogen and helium. It became known in the 1990s that Uranus and Neptune were really a distinct class of giant planet, composed of about 20% hydrogen, compared to the heavier gas giant's 90%. The Nice model, in fact, suggests that Neptune formed closer to the Sun than Uranus did, and would therefore have more heavy elements.


 * History of Solar System formation and evolution hypotheses
 * Nice model (city Nice in France): scenario for the dynamical evolution of the Solar System. It proposes the migration of the giant planets from an initial compact configuration into their present positions, long after the dissipation of the initial protoplanetary gas disk. This planetary migration is used in dynamical simulations of the Solar System to explain historical events including the Late Heavy Bombardment of the inner Solar System, the formation of the Oort cloud, and the existence of populations of small Solar System bodies including the Kuiper belt, the Neptune and Jupiter Trojans, and the numerous resonant trans-Neptunian objects dominated by Neptune.
 * Jumping-Jupiter Scenario: specifies an evolution of the giant planet migration described by the Nice model in which an ice giant planet (Uranus, Neptune, or an additional Neptune-mass planet) encounters first Saturn and then Jupiter causing the step-wise separation of their orbits.
 * Hypothetical fifth gas giant: an additional planet added by some theorists to recent versions of the Nice model. The fifth giant planet is ejected from the Solar System following gravitational encounters with Saturn and Jupiter. The inclusion of five giant planets in numerical models of the early Solar System has been shown to increase the likelihood of their reproducing the current Solar System.


 * Small Solar System body: object in the Solar System that is neither a planet, a dwarf planet, nor a natural satellite. The term was first defined in 2006 by the IAU as follows: "All other objects, except satellites, orbiting the Sun shall be referred to collectively as 'Small Solar System Bodies'". This encompasses all comets and all minor planets other than those that are dwarf planets. Thus SSSBs are: the comets; the classical asteroids, with the exception of the dwarf planet Ceres; the trojans; and the centaurs and trans-Neptunian objects, with the exception of the dwarf planets Pluto, Haumea, Makemake, and Eris and others that may turn out to be dwarf planets.
 * Scattered disc: distant circumstellar disc in the Solar System that is sparsely populated by icy minor planets, a subset of the broader family of trans-Neptunian objects.
 * Kuiper belt: circumstellar disc in the Solar System beyond the planets, extending from the orbit of Neptune (at 30 AU) to approximately 50 AU from the Sun. It is similar to the asteroid belt, but it is far larger—20 times as wide and 20 to 200 times as massive. Like the asteroid belt, it consists mainly of small bodies, or remnants from the Solar System's formation. Although many asteroids are composed primarily of rock and metal, most Kuiper belt objects are composed largely of frozen volatiles (termed "ices"), such as methane, ammonia and water. The Kuiper belt is home to three officially recognized dwarf planets: Pluto, Haumea, and Makemake. Some of the Solar System's moons, such as Neptune's Triton and Saturn's Phoebe, are also thought to have originated in the region.
 * Asteroid: minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are metallic or rocky bodies with no atmosphere. Of the roughly one million known asteroids the greatest number of them are located between the orbits of Mars and Jupiter, approximately 2 to 4 AU from the Sun, in the main asteroid belt. Asteroids are generally classified to be of three types: C-type, M-type, and S-type. These were named after and are generally identified with carbonaceous, metallic, and silicaceous compositions, respectively. When found, asteroids were seen as a class of objects distinct from comets, and there was no unified term for the two until "small Solar System body" was coined in 2006. The main difference between an asteroid and a comet is that a comet shows a coma due to sublimation of near-surface ices by solar radiation. A few objects have ended up being dual-listed because they were first classified as minor planets but later showed evidence of cometary activity. Conversely, some (perhaps all) comets are eventually depleted of their surface volatile ices and become asteroid-like. A further distinction is that comets typically have more eccentric orbits than most asteroids; "asteroids" with notably eccentric orbits are probably dormant or extinct comets.
 * Comet: an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena are due to the effects of solar radiation and the solar wind acting upon the nucleus of the comet. Comet nuclei range from a few hundred meters to tens of kilometers across and are composed of loose collections of ice, dust, and small rocky particles. The coma may be up to 15 times Earth's diameter, while the tail may stretch beyond 1 au. If sufficiently bright, a comet may be seen from Earth without the aid of a telescope and may subtend an arc of 30° (60 Moons) across the sky. Comets have been observed and recorded since ancient times by many cultures and religions. The discovery of main-belt comets and active centaur minor planets has blurred the distinction between asteroids and comets. In the early 21st century, the discovery of some minor bodies with long-period comet orbits, but characteristics of inner solar system asteroids, were called Manx comets.
 * Centaur (small Solar System body): small Solar System body with either a perihelion or a semi-major axis between those of the outer planets. Centaurs generally have unstable orbits because they cross or have crossed the orbits of one or more of the giant planets; almost all their orbits have dynamic lifetimes of only a few million years, but there is one known centaur, 514107 Kaʻepaokaʻawela, which may be in a stable (though retrograde) orbit. Centaurs typically exhibit the characteristics of both asteroids and comets. They are named after the mythological centaurs that were a mixture of horse and human. Observational bias toward large objects makes determination of the total centaur population difficult. Estimates for the number of centaurs in the Solar System more than 1 km in diameter range from as low as 44,000 to more than 10,000,000.
 * Trans-Neptunian object (transneptunian object): any minor planet in the Solar System that orbits the Sun at a greater average distance than Neptune, which has a semi-major axis of 30.1 au.


 * Exoplanet
 * Super-Earth: extrasolar planet with a mass higher than Earth's, but substantially below the mass of the Solar System's ice giants Uranus and Neptune, which are 15 and 17 Earth masses respectively. The term super-Earth refers only to the mass of the planet, and does not imply anything about the surface conditions or habitability.


 * List of gravitationally rounded objects of the Solar System: which are objects that have a rounded, ellipsoidal shape due to the forces of their own gravity (hydrostatic equilibrium). Their sizes range from dwarf planets and moons to the planets and the Sun. Equatorial gravity (m/s²): Earth 9.81, Mars 3.71, Venus 8.87, Moon 1.622, Io 1.796, Ganymede 1.428, Titan 1.35, Europa 1.314, Callisto 1.235




 * Template:Spacecraft by destination
 * List of missions to the outer planets: nine spacecraft have been launched on missions that involve visits to the outer planets; all nine missions involve encounters with Jupiter, with four spacecraft also visiting Saturn. One spacecraft, Voyager 2, also visited Uranus and Neptune. Ulysses and New Horizons, whose primary objectives are not related to the outer planets, but which flew past Jupiter to gain gravity assists en route to a polar orbit around the Sun, and Pluto—at the time of its launch considered an outer planet—respectively. Cassini–Huygens also flew past Jupiter for a gravity assist on its Mission to explore Saturn. Only three of the missions to the outer planets have been orbiters : Galileo orbited Jupiter for eight years (1995-2003), while Cassini orbited Saturn for thirteen years (2004-2017). Juno has been orbiting Jupiter since 2016.


 * Murchison meteorite: meteorite that fell in Australia in 1969 near Murchison, Victoria. It belongs to a group of meteorites rich in organic compounds. Due to its mass (over 100 kg) and the fact that it was an observed fall, the Murchison meteorite is one of the most studied of all meteorites. In January 2020, cosmochemists reported that the oldest material found on Earth to date is the silicon carbide particles from the Murchison meteorite, which have been determined to be 7 billion years old, about 2.5 billion years older than the 4.54-billion-year age of the Earth and the Solar System. The published study noted that "dust lifetime estimates mainly rely on sophisticated theoretical models. These models, however, focus on the more common small dust grains and are based on assumptions with large uncertainties."


 * Local Bubble (Local Cavity): relative cavity in the interstellar medium (ISM) of the Orion Arm in the Milky Way. It contains the closest of celestial neighbours and among others, the Local Interstellar Cloud (which contains the Solar System), the neighbouring G-Cloud, Ursa Major Moving Group (the closest stellar moving group) and the Hyades (the nearest open cluster). It is at least 300 light years across, and is defined by its neutral-hydrogen density of about 0.05 atoms/cm³, or approximately one tenth of the average for the ISM in the Milky Way (0.5 atoms/cm³), and one sixth that of the Local Interstellar Cloud (0.3 atoms/cm³). The exceptionally sparse gas of the Local Bubble is the result of supernovae that exploded within the past ten to twenty million years. The gas remains in an excited state, emitting in the X-ray band.
 * Local Interstellar Cloud (Local Fluff): interstellar cloud roughly 30 light-years (9.2 pc) across, through which the Solar System is moving. It is unknown if the Sun is embedded in the Local Interstellar Cloud, or in the region where the Local Interstellar Cloud is interacting with the neighboring G-Cloud.
 * G-Cloud: interstellar cloud located next to the Local Interstellar Cloud, within the Local Bubble. It is unknown whether the Solar System is embedded in the Local Interstellar Cloud or in the region where the two clouds are interacting, although the Solar System is currently moving towards the G-Cloud. The G-Cloud contains the stars Alpha Centauri (a triple star system that includes Proxima Centauri) and Altair (and possibly others).

Space probes:
 * New Horizons: interplanetary space probe that was launched as a part of NASA's New Frontiers program. Engineered by the Johns Hopkins University Applied Physics Laboratory (APL) and the Southwest Research Institute (SwRI), with a team led by Alan Stern, the spacecraft was launched in 2006 with the primary mission to perform a flyby study of the Pluto system in 2015, and a secondary mission to fly by and study one or more other Kuiper belt objects (KBOs) in the decade to follow, which became a mission to 486958 Arrokoth. It is the fifth space probe to achieve the escape velocity needed to leave the Solar System.


 * List of objects at Lagrange points:
 * Sun–Earth Lagrange points:
 * Sun–Earth L1: Present probes: Solar and Heliospheric Observatory (SOHO) in a halo orbit; Advanced Composition Explorer (ACE) in a Lissajous orbit; WIND (At L1 since 2004); Deep Space Climate Observatory (DSCOVR), designed to image the sunlit Earth in 10 wavelengths (EPIC) and monitor total reflected radiation (NISTAR).
 * Sun–Earth L2: Present probes: ESA Gaia probe; joint Russian-German high-energy astrophysics observatory Spektr-RG; joint NASA, ESA and CSA James Webb Space Telescope (JWST)

History of human understanding of Solar System

 * Planet: astronomical body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and – according to IAU but not all planetary scientists – has cleared its neighbouring region of planetesimals. The term planet is ancient, with ties to history, astrology, science, mythology, and religion. Apart from Earth itself, five planets in the Solar System are often visible to the naked eye. These were regarded by many early cultures as divine, or as emissaries of deities.
 * Classical planet (seven classical planets or seven luminaries): seven moving astronomical objects in the sky visible to the naked eye: the Moon, Mercury, Venus, the Sun, Mars, Jupiter, and Saturn. The word planet comes from two related Greek words, πλάνης planēs (whence πλάνητες ἀστέρες planētes asteres "wandering stars, planets") and πλανήτης planētēs, both with the original meaning of "wanderer", expressing the fact that these objects move across the celestial sphere relative to the fixed stars. Greek astronomers such as Geminus and Ptolemy often divided the seven planets into the Sun, the Moon, and the five planets.

Sun

 * Template:The Sun
 * Template:Sun spacecraft


 * Sun: star at the center of the Solar System; nearly perfect sphere of hot plasma, with internal convective motion that generates a magnetic field via a dynamo process; by far the most important source of energy for life on Earth . Its diameter is about 1.39 million kilometers, i.e. 109 times that of Earth, and its mass is about 330,000 times that of Earth, accounting for about 99.86% of the total mass of the Solar System. Hydrogen (~73%), helium (~25%), with much smaller quantities of heavier elements, including oxygen, carbon, neon, and iron. The Sun is a G-type main-sequence star (G2V) based on its spectral class. As such, it is informally referred to as a yellow dwarf. It formed approximately 4.6 bln. years ago from the gravitational collapse of matter within a region of a large molecular cloud. Most of this matter gathered in the center, whereas the rest flattened into an orbiting disk that became the Solar System. The central mass became so hot and dense that it eventually initiated nuclear fusion in its core.


 * Sunspot
 * Maunder Minimum ("prolonged sunspot minimum"): name used for the period starting in about 1645 and continuing to about 1715 when sunspots became exceedingly rare, as noted by solar observers of the time. Spörer noted that, during a 28-year period (1672–1699) within the Maunder Minimum, observations revealed fewer than 50 sunspots. This contrasts with the typical 40,000–50,000 sunspots seen in modern times. Little Ice Age
 * Modern Maximum: period of relatively high solar activity which began with Solar Cycle 15 in 1914. It reached a maximum in Cycle 19 during the late 1950s and may have ended with Cycle 23 in 2000 as Cycle 24 is recording, at best, very muted solar activity. This period is a natural example of solar variation, and one of many that are known from proxy records of past solar variability. The Modern Maximum reached a double peak once in the 1950s and again during the 1990s.


 * Template:Solar storms:
 * Solar storm of 1859 (solar superstorm, Carrington Event; 1859.08.28-09.02): the largest known solar flare; huge magnetic storm: telegraph systems in Europe and North America failed.
 * Aurora of November 17, 1882: "auroral beam"


 * Helios (spacecraft) (Helios-A and Helios-B): pair of probes that were launched into heliocentric orbit to study solar processes. As a joint venture of West Germany's space agency DLR (70% share) and NASA (30% share) the probes were launched from Cape Canaveral Air Force Station, Florida, in 1974.12.10, and 1976.01.15, respectively. As built by the main contractor, Messerschmitt-Bölkow-Blohm, they were the first space probes built outside the United States and the Soviet Union to leave Earth's orbit. The probes set a maximum speed record for spacecraft of 252,792 km/h (70,220 m/s). Helios-B flew 3,000,000 kilometres closer to the Sun than Helios-A, achieving perihelion in 1976.04.17, at a record distance of 43.432 million km (0.29032 AU), closer than the orbit of Mercury. Thermal control: The biggest technical challenge faced by the designers was the heat that the probe was subject to when close to the Sun. At 0.3 astronomical units (45,000,000 km) from the Sun, approximate heat flow is 11 solar constants, (11 times the amount of received heat in Earth orbit), or 22.4 kW per exposed square meter. Under these conditions, the temperature of the probe can then reach 370 °C.


 * Parker Solar Probe: NASA space probe launched in 2018 with the mission of making observations of the outer corona of the Sun. It will approach to within 9.86 solar radii (6.9 million km) from the center of the Sun, and by 2025 will travel, at closest approach, as fast as 690,000 km/h, or 0.064% the speed of light. In 2018.10.29, at about 18:04 UTC, the spacecraft became the closest ever artificial object to the Sun. The previous record, 42.73 million kilometres from the Sun's surface, was set by the Helios 2 spacecraft in 1976.04. As of its perihelion 2021.11.21, the Parker Solar Probe's closest approach is 8.5 million kilometres. This will be surpassed after each of the two remaining flybys of Venus.
 * Solar Orbiter (SolO): Sun-observing satellite developed by ESA. SolO, designed to obtain detailed measurements of the inner heliosphere and the nascent solar wind, will also perform close observations of the polar regions of the Sun which is difficult to do from Earth. These observations are important in investigating how the Sun creates and controls its heliosphere. SolO makes observations of the Sun from an eccentric orbit moving as close as ≈60 solar radii (RS), or 0.284 au, placing it inside Mercury's perihelion of 0.3075 au. During the mission the orbital inclination will be raised to about 24°.

Moon exploration

 * List of missions to the Moon


 * Orbit of the Moon: Moon orbits Earth in the prograde direction and completes one revolution relative to the Vernal Equinox and the stars in about 27.32 days (a tropical month and sidereal month). Earth and the Moon orbit about their barycentre (common center of mass), which lies about 4,670 km (2,900 mi) from Earth's center (about 73% of its radius). On average, the distance to the Moon is about 385,000 km (239,000 mi) from Earth's center, which corresponds to about 60 Earth radii or 1.282 light-seconds.

{q.v. NASA : Apollo program}
 * Tranquility Base: site on the Moon where, in 1969, humans landed and walked on another celestial body for the first time. 1969.07.20, Apollo 11 crewmembers Neil Armstrong and Buzz Aldrin landed their Apollo Lunar Module Eagle at approximately 20:17:40 UTC. Six hours later, the two astronauts exited the spacecraft and spent 2 hours 31 minutes on the lunar surface, examining and photographing it, setting up some scientific experiment packages, and collecting 21.5 kg of dirt and rock samples for return to Earth. They lifted off the surface on July 21 at 17:54 UTC. Tranquility Base has remained unvisited since then.


 * Lunar Reconnaissance Orbiter: NASA robotic spacecraft currently orbiting the Moon in a low 50 km polar mapping orbit; precursor to future manned missions to the Moon by NASA; provided some of the first images of Apollo equipment left on the Moon.


 * Lunar Gateway: planned small space station in lunar orbit intended to serve as a solar-powered communication hub, science laboratory, short-term habitation module for government-agency astronauts, as well as a holding area for rovers and other robots. It is a multinational collaborative project involving four of the International Space Station partner agencies: NASA, ESA, JAXA, and CSA. It is planned to be both the first space station beyond low Earth orbit and the first space station to orbit the Moon.

Venus exploration

 * Template:Venus


 * List of missions to Venus


 * Akatsuki (spacecraft) (あかつき, 暁, "Dawn"; Venus Climate Orbiter (VCO)): JAXA space probe tasked to study the atmosphere of Venus. It was launched aboard an H-IIA 202 rocket in 2010.05.20, and failed to enter orbit around Venus on 2010.12.06. After the craft orbited the Sun for five years, engineers successfully placed it into an alternative Venusian elliptic orbit on 2015.12.07 by firing its attitude control thrusters for 20 minutes and made it the first Asian satellite orbiting Venus. By using five different cameras working at several wavelengths, Akatsuki is studying the stratification of the atmosphere, atmospheric dynamics, and cloud physics.

Mars exploration

 * Template:Mars


 * List of missions to Mars


 * Robert Zubrin: USA aerospace engineer, author, and advocate for human exploration of Mars. He and his colleague at Martin Marietta, David Baker, were the driving force behind Mars Direct, a proposal in a 1990 research paper intended to produce significant reductions in the cost and complexity of such a mission. The key idea was to use the Martian atmosphere to produce oxygen, water, and rocket propellant for the surface stay and return journey. A modified version of the plan was subsequently adopted by NASA as their "design reference mission". He questions the delay and cost-to-benefit ratio of first establishing a base or outpost on an asteroid or another Apollo program-like return to the Moon, as neither would be able to provide all of its own oxygen, water, or energy; these resources are producible on Mars, and he expects people would be there thereafter.
 * The Case for Mars: Zubrin decisively denounces and rejects suggestions that the Moon should be used as waypoint to Mars or as a training area. It is ultimately much easier to journey to Mars from low Earth orbit than from the moon and using the latter as a staging point is a pointless diversion of resources. While the Moon may superficially appear a good place to perfect Mars exploration and habitation techniques, the two bodies are radically different. The moon has no atmosphere, no analogous geology and a much greater temperature range and rotational period. Antarctica or desert areas of Earth provide much better training grounds at lesser cost.
 * Mars Society: nonprofit organization that advocates for human Mars exploration and colonization, founded by Robert Zubrin in 1998. It is based on Zubrin's Mars Direct plan, which aims to make human mission to Mars as lightweight and feasible as possible. The Mars Society aims to garner support for the Mars program by lobby the United States and other governments. Mars analog habitats: In mid-2001, the Mars Society received a $5000 check from Elon Musk for a fundraiser event. Zubrin took notice and invited Musk for coffee. There, he talked about the Flashline Mars Arctic Research Station and the Translife Mission which included experiments where a spinning capsule would subject mice to Martian gravity. After briefly researching about Mars concepts and missions, Musk joined the Mars Society's board of directors and gave it $100,000. The money was to be used on the next Mars analog habitat, called MDRS. He left the Mars Society shortly after, wanting to do a Mars-related publicity stunt mission on his own. In April 2002, Musk abandoned the project and founded SpaceX, inviting aerospace engineers that he had met beforehand.
 * Mars Desert Research Station (MDRS): largest and longest-running Mars surface research facility in the world and is one of two simulated Mars analog habitats owned and operated by the Mars Society. The MDRS station was built in the early 2000s near Hanksville, Utah, in the western USA. The MDRS campus includes a two-story habitat (referred to as "the Hab"), a greenhouse (referred to as "the GreenHab"), the solar-related Musk Observatory, a robotic observatory, an engineering pod (referred to as "the RAM"), and a science building (referred to as "the Science Dome").


 * Mars rover: motor vehicle that travels across the surface of the planet Mars upon arrival. Rovers have several advantages over stationary landers: they examine more territory, they can be directed to interesting features, they can place themselves in sunny positions to weather winter months, and they can advance the knowledge of how to perform very remote robotic vehicle control. As of February 2021, there have been five successful robotically operated Mars rovers, all managed by the Jet Propulsion Laboratory: Sojourner (Mars Pathfinder robotic spacecraft), Opportunity (MER-A), Spirit (MER-B), Curiosity (MSL), and Perseverance (Mars 2020).


 * Mars Science Laboratory:
 * Curiosity (rover): car-sized robotic rover exploring Gale Crater on Mars as part of NASA's Mars Science Laboratory mission (MSL).
 * Timeline of Mars Science Laboratory: Curiosity has been on the planet Mars for sols ( total days) since landing on 2012.08.06.


 * Mars to Stay: missions propose astronauts sent to Mars for the first time should intend to stay. Unused emergency return vehicles would be recycled into settlement construction as soon as the habitability of Mars becomes evident to the initial pioneers. Mars to Stay missions are advocated both to reduce cost and to ensure permanent settlement of Mars. Among many notable Mars to Stay advocates, former Apollo astronaut Buzz Aldrin has been particularly outspoken, suggesting in numerous forums "Forget the Moon, Let’s Head to Mars!" and, in June 2013, Aldrin promoted a manned mission "to homestead Mars and become a two-planet species". Davies argues that since "some people gleefully dice with death in the name of sport or adventure [and since] dangerous occupations that reduce life expectancy through exposure to hazardous conditions or substances are commonplace", we ought to not find the risks involved in a Mars to Stay architecture unusual. "A century ago, explorers set out to trek across Antarctica in the full knowledge that they could die in the process, and that even if they succeeded their health might be irreversibly harmed. Yet governments and scientific societies were willing sponsors of these enterprises." Davies then asks, "Why should it be different today?"
 * HI-SEAS (Hawaii Space Exploration Analog and Simulation): analog habitat for human spaceflight to Mars. HI-SEAS is located in an isolated position on the slopes of the Mauna Loa volcano on the island of Hawaii. The area has Mars-like features and an elevation of approximately 8,200 feet (2,500 m) above sea level. The first HI-SEAS study was in 2013 and NASA's Human Research Program continues to fund and sponsor follow-up studies. The missions are of extended duration from four months to a year. One thing under study by NASA is trying to understand crew dynamics such as morale, stress management, and how they solve problems as group.


 * Climate of Mars: Mars is the only terrestrial planet whose surface can be directly observed in detail from the Earth with help from a telescope. Although Mars is smaller than the Earth, 11% of Earth's mass, and 50% farther from the Sun than the Earth, its climate has important similarities, such as the presence of polar ice caps, seasonal changes and observable weather patterns. It has attracted sustained study from planetologists and climatologists. While Mars' climate has similarities to Earth's, including periodic ice ages, there are also important differences, such as much lower thermal inertia. Mars has been studied by Earth-based instruments since the 17th century, but it is only since the exploration of Mars began in the mid-1960s that close-range observation has been possible. Flyby and orbital spacecraft have provided data from above, while landers and rovers have measured atmospheric conditions directly. Advanced Earth-orbital instruments today continue to provide some useful "big picture" observations of relatively large weather phenomena.

Mercury exploration

 * BepiColombo: joint mission of ESA and JAXA to the planet Mercury. The mission comprises two satellites launched together: the Mercury Planetary Orbiter (MPO) and Mio (Mercury Magnetospheric Orbiter, MMO). The mission will perform a comprehensive study of Mercury, including characterization of its magnetic field, magnetosphere, and both interior and surface structure.

Jupiter

 * Template:Jupiter


 * Jupiter: fifth planet from the Sun and the largest in the Solar System. It is a giant planet with a mass one-thousandth that of the Sun, but two and a half times that of all the other planets in the Solar System combined. Jupiter is a gas giant.
 * Atmosphere of Jupiter: largest planetary atmosphere in the Solar System. It is mostly made of molecular hydrogen and helium in roughly solar proportions; other chemical compounds are present only in small amounts and include methane, ammonia, hydrogen sulfide and water. The nitrogen, sulfur, and noble gas abundances in Jupiter's atmosphere exceed solar values by a factor of about three. The atmosphere of Jupiter lacks a clear lower boundary and gradually transitions into the liquid interior of the planet. From lowest to highest, the atmospheric layers are the troposphere, stratosphere, thermosphere and exosphere. The vortices reveal themselves as large red, white or brown spots (ovals). The largest two spots are the Great Red Spot (GRS) and Oval BA, which is also red. These two and most of the other large spots are anticyclonic.
 * Magnetosphere of Jupiter


 * Comet Shoemaker–Levy 9: comet that broke apart and collided with Jupiter in July 1994, providing the first direct observation of an extraterrestrial collision of Solar System objects. These fragments due to a previous closer approach to Jupiter in 1992.07 collided with Jupiter's southern hemisphere 1994.07.16-22, at a speed of approximately 60 km/s or 216,000 km/h. The prominent scars from the impacts were more easily visible than the Great Red Spot and persisted for many months.
 * 2009 Jupiter impact event: July 2009 impact on Jupiter that caused a black spot in the planet's atmosphere. The impact area covered 190 million square kilometers, similar in area to the planet's Little Red Spot and approximately the size of the Pacific Ocean. The impactor is estimated to have been about 200 to 500 meters in diameter.


 * Moons of Jupiter
 * Galilean moons: four largest moons of Jupiter—Io, Europa, Ganymede, and Callisto. They were first seen by Galileo Galilei in January 1610, and recognized by him as satellites of Jupiter in March 1610. They were the first objects found to orbit another planet. Their names derive from the lovers of Zeus. They are among the largest objects in the Solar System with the exception of the Sun and the eight planets, with a radius larger than any of the dwarf planets. Ganymede is the largest moon in the Solar System, and is even bigger than the planet Mercury, though only around half as massive. The three inner moons—Io, Europa, and Ganymede—are in a 4:2:1 orbital resonance with each other. Galilean moons
 * Ganymede (moon): largest and most massive moon of Jupiter and in the Solar System. The ninth largest object in the Solar System, it is the largest without a substantial atmosphere.

Saturn

 * Template:Saturn


 * Saturn's hexagon: persisting hexagonal cloud pattern around the north pole of Saturn, located at about 78°N. The sides of the hexagon are about 13,800 km long, which is more than the diameter of Earth (about 12,700 km). It rotates with a period of 10h 39m 24s, the same period as Saturn's radio emissions from its interior. The hexagon does not shift in longitude like other clouds in the visible atmosphere. Saturn's south pole does not have a hexagon, according to Hubble observations; however, it does have a vortex, and there is also a vortex inside the northern hexagon. Saturn's polar hexagon discovery was made by the Voyager mission in 1981, and it was revisited in 2006 by the Cassini mission.
 * Great White Spot: periodic storms that are large enough to be visible by telescope from Earth by their characteristic white appearance. The spots can be several thousands of kilometers wide.


 * Moons of Saturn: numerous and diverse, ranging from tiny moonlets less than 1 kilometer across to the enormous Titan, which is larger than the planet Mercury. Moons of Saturn
 * Titan (moon): largest moon of Saturn. It is the only moon known to have a dense atmosphere, and the only object in space, other than Earth, where clear evidence of stable bodies of surface liquid have been found. Titan is the sixth gravitationally rounded moon from Saturn. Frequently described as a planet-like moon, Titan is 50% larger than Earth's moon and 80% more massive. It is the second-largest moon in the solar system after Jupiter's moon Ganymede, and is larger than the smallest planet, Mercury, but only 40% as massive. The atmosphere of Titan is largely nitrogen; minor components lead to the formation of methane and ethane clouds and nitrogen-rich organic smog. The climate—including wind and rain—creates surface features similar to those of Earth, such as dunes, rivers, lakes, seas (probably of liquid methane and ethane), and deltas, and is dominated by seasonal weather patterns as on Earth. With its liquids (both surface and subsurface) and robust nitrogen atmosphere, Titan's methane cycle is analogous to Earth's water cycle, at the much lower temperature of about 94 K (−179.2 °C).
 * Enceladus: 6th-largest moon of Saturn. It is about 500 km in diameter, about a tenth of that of Saturn's largest moon, Titan.

Asteroids

 * Category:Asteroid mining
 * Category:Space law in the United States


 * Asteroid mining: hypothetical exploitation of materials from asteroids and other minor planets, including near-Earth objects. Notable asteroid mining challenges include the high cost of spaceflight, unreliable identification of asteroids which are suitable for mining, and the challenges of extracting usable material in a space environment. As of 2021, less than 1 gram of asteroid material has been successfully returned to Earth from space. In progress missions promise to increase this amount to approximately 60 grams.


 * Ceres (dwarf planet) (minor-planet designation: 1 Ceres): dwarf planet in the asteroid belt between the orbits of Mars and Jupiter. It was the first asteroid discovered, on 1 January 1801, by Giuseppe Piazzi at Palermo Astronomical Observatory in Sicily. In 2006, it was reclassified again as a dwarf planet – the only one always inside Neptune's orbit – because, at 940 km in diameter, it is the only asteroid large enough for its gravity to maintain it as a spheroid in hydrostatic equilibrium. Ceres's small size means that even at its brightest it is too dim to be seen by the naked eye, except under extremely dark skies. Its apparent magnitude ranges from 6.7 to 9.3, peaking at opposition (when it is closest to Earth) once every 15- to 16-month synodic period. Its surface features are barely visible even with the most powerful telescopes, and little was known of them until the robotic NASA spacecraft Dawn approached Ceres for its orbital mission in 2015. Dawn found Ceres's surface to be a mixture of water ice and hydrated minerals such as carbonates and clay. Gravity data suggest Ceres to be partially differentiated into a muddy (ice-rock) mantle/core and a less-dense but stronger crust that is at most 30% ice by volume. Ceres's small size means that any internal ocean of liquid water it may once have possessed has likely frozen by now. It is not completely frozen, however: brines still flow through the outer mantle and reach the surface, allowing cryovolcanoes such as Ahuna Mons to form at the rate of about one every 50 million years. This makes Ceres the closest known cryovolcanic body to the Sun, and the brines provide a potential habitat for microbial life. In January 2014, emissions of water vapor were detected around Ceres, creating a tenuous, transient atmosphere known as an exosphere. This was unexpected because asteroids typically do not emit vapor, a hallmark of comets.

Planetary science

 * Category:Planetary science
 * Category:Impact events
 * Category:Planetary defense
 * Category:Planetary geology
 * Category:Impact geology
 * Category:Earth Impact Database


 * Template:Modern impact events

{q.v. }


 * Asteroid impact avoidance: comprises a number of methods by which near-Earth objects (NEO) could be diverted, preventing destructive impact events. A sufficiently large impact by an asteroid or other NEOs would cause, depending on its impact location, massive tsunamis, multiple firestorms and an impact winter caused by the sunlight blocking effect of placing large quantities of pulverized rock dust, and other debris, into the stratosphere. A collision between the Earth and an approximately 10-kilometre-wide object 66 million years ago is thought to have produced the Chicxulub Crater and the Cretaceous–Paleogene extinction event, widely held responsible for the extinction of the dinosaurs.


 * Chelyabinsk meteor: superbolide caused by a near-Earth asteroid that entered Earth's atmosphere over Russia on 2013.02.15 at about 09:20 YEKT (03:20 UTC), with a speed of 19.16±0.15 km/s. It quickly became a brilliant superbolide meteor over the southern Ural region. The light from the meteor was brighter than the Sun, up to 100 km away. 500 kilotons of TNT (about 1.8 PJ), 20–30 times more energy than was released from the atomic bomb detonated at Hiroshima.

Universe, Cosmology

 * Category:Universe
 * Category:Cosmology
 * Category:Physical cosmology


 * The Celestial Zoo infographic wikimedia.png


 * Template:Earth's location: Earth → Solar System → Local Interstellar Cloud → Local Bubble → Gould Belt → Orion Arm → Milky Way → Milky Way subgroup → Local Group → Virgo Supercluster → Laniakea Supercluster → Observable universe → Universe


 * Multiverse: hypothetical set of all universes. Together, these universes are presumed to comprise everything that exists: the entirety of space, time, matter, energy, information, and the physical laws and constants that describe them. The different universes within the multiverse are called "parallel universes", "other universes", "alternate universes", or "many worlds". One common assumption is that the multiverse is a "patchwork quilt of separate universes all bound by the same laws of physics."
 * Mathematical universe hypothesis (ultimate ensemble theory): speculative "theory of everything" (TOE) proposed by cosmologist Max Tegmark.


 * Observable universe: spherical region of the Universe comprising all matter that can be observed from Earth at the present time, because electromagnetic radiation from these objects has had time to reach Earth since the beginning of the cosmological expansion. There are at least 2 trillion galaxies in the observable universe, containing more stars than all the grains of sand on planet Earth. Assuming the Universe is isotropic, the distance to the edge of the observable universe is roughly the same in every direction. That is, the observable universe is a spherical volume (a ball) centered on the observer. Every location in the Universe has its own observable universe, which may or may not overlap with the one centered on Earth.


 * Inflation (cosmology) (cosmic inflation, cosmological inflation): theory of exponential expansion of space in the early universe. The inflationary epoch lasted from 10⁻³⁶ seconds after the conjectured Big Bang singularity to some time between 10⁻³³ and 10⁻³² seconds after the singularity. Following the inflationary period, the universe continued to expand, but at a slower rate. The acceleration of this expansion due to dark energy began after the universe was already over 7.7 billion years old (5.4 billion years ago). The detailed particle physics mechanism responsible for inflation is unknown. The basic inflationary paradigm is accepted by most physicists, as a number of inflation model predictions have been confirmed by observation; however, a substantial minority of scientists dissent from this position. The hypothetical field thought to be responsible for inflation is called the inflaton field.


 * UniverseMachine: project of an ongoing series of astrophysical supercomputer simulations of various models of possible universes, that was created by astronomer Peter Behroozi and his research team at the Steward Observatory and the University of Arizona. As such, numerous universes with different physical characteristics may be simulated in order to develop insights into the possible beginning, and later evolution, of our current universe. One of the major objectives of the project is to better understand the role of dark matter in the development of the universe. According to Behroozi, "On the computer, we can create many different universes and compare them to the actual one, and that lets us infer which rules lead to the one we see."


 * Bolshoi Cosmological Simulation: computer model of the universe run in 2010 on the Pleiades supercomputer at the NASA Ames Research Center, was the most accurate cosmological simulation to that date of the evolution of the large-scale structure of the universe. The Bolshoi simulation used the now-standard ΛCDM (Lambda-CDM) model of the universe and the WMAP five-year and seven-year cosmological parameters from NASA's Wilkinson Microwave Anisotropy Probe team. "The principal purpose of the Bolshoi simulation is to compute and model the evolution of dark matter halos, thereby rendering the invisible visible for astronomers to study, and to predict visible structure that astronomers can seek to observe."


 * N-body simulation: of a dynamical system of particles, usually under the influence of physical forces, such as gravity (see n-body problem). N-body simulations are widely used tools in astrophysics, from investigating the dynamics of few-body systems like the Earth-Moon-Sun system to understanding the evolution of the large-scale structure of the universe.


 * Black Hole Initiative: "If determinism — the predictability of the universe — breaks down in black holes, it could break down in other situations. Even worse, if determinism breaks down, we can’t be sure of our past history either. The history books and our memories could just be illusions. It is the past that tells us who we are. Without it, we lose our identity." — Stephen Hawking, BHI Inauguration, Harvard University, 2016.04.18

Gravity, gravitation, general relativity

 * Category:Gravity
 * Category:Theories of gravity
 * Category:General relativity
 * Category:Gravitational-wave astronomy
 * Category:Gravitational waves
 * Category:Mathematical methods in general relativity


 * Gravitational wave observation (2016.02.11): LIGO and Virgo collaborations announced the first observation of gravitational waves. Waveform, detected on 2015.09.14 by Marco Drago, physicist at the Albert Einstein Institute in Hannover, Germany, matched the predictions of general relativity for the inward spiral and merger of a pair of black holes and subsequent 'ringdown' of the resulting single black hole. The signal was named GW150914.


 * Kerr metric (Kerr geometry): geometry of empty spacetime around a rotating uncharged axially-symmetric black hole with a spherical event horizon. The Kerr metric is an exact solution of the Einstein field equations of general relativity; these equations are highly non-linear, which makes exact solutions very difficult to find.


 * Cosmic censorship hypothesis: two mathematical conjectures about the structure of singularities arising in general relativity. Singularities that arise in the solutions of Einstein's equations are typically hidden within event horizons, and therefore cannot be seen from the rest of spacetime. Singularities that are not so hidden are called naked. The weak cosmic censorship hypothesis was conceived by Roger Penrose in 1969 and posits that no naked singularities, other than the Big Bang singularity, exist in the universe.


 * Numerical relativity: uses numerical methods and algorithms to solve and analyze problems. To this end, supercomputers are often employed to study black holes, gravitational waves, neutron stars and many other phenomena governed by Einstein's theory of general relativity. History: Foundations in theory; Maturation of the field: Excision, Punctures, Breakthrough, Lazarus project (1998–2005), Adaptive mesh refinement. Recent developments: technique extended to astrophysical binary systems involving neutron stars and black holes, and multiple black holes. One of the most surprising predictions is that the merger of two black holes can give the remnant hole a speed of up to 4000 km/s that can allow it to escape from any known galaxy. The simulations also predict an enormous release of gravitational energy in this merger process, amounting up to 8% of its total rest mass.


 * List of gravitational wave observations: Direct observation of gravitational waves, which commenced with the detection of an event by LIGO in 2015, constitutes part of gravitational wave astronomy. LIGO has played a role in all subsequent detections to date, with Virgo joining in August 2017.
 * First observation of gravitational waves (GW150914; 2015.09.14): announced by the LIGO and Virgo collaborations in 2016.02.11. Previously, gravitational waves had been inferred only indirectly, via their effect on the timing of pulsars in binary star systems. The waveform, detected by both LIGO observatories, matched the predictions of general relativity for a gravitational wave emanating from the inward spiral and merger of a pair of black holes of around 36 and 29 solar masses and the subsequent "ringdown" of the single resulting black hole.


 * Roger Babson (1875.07.06–1967.03.05): USA entrepreneur, economist, and business theorist in the first half of the 20th century. He is best remembered for founding Babson College. He also founded Webber College, now Webber International University, in Babson Park, Florida, and the defunct Utopia College, in Eureka, Kansas. Roger attended MIT and worked for investment firms before founding Babson's Statistical Organization (1904), which analyzed stocks and business reports; it continues today as Babson-United, Inc.
 * Gravity Research Foundation: organization established in 1948 by businessman Roger Babson (founder of Babson College) to find ways to implement gravitational shielding. It holds an annual contest rewarding essays by scientific researchers on gravity-related topics. The contest, which awards prizes of up to $4,000, has been won by at least six people who later won the Nobel Prize in physics. The foundation held conferences and conducted operations in New Boston, New Hampshire through the late 1960s, but that aspect of its operation ended following Babson's death in 1967. In an essay titled Gravity – Our Enemy Number One, Babson indicated that his wish to overcome gravity dated from the childhood drowning of his sister. "She was unable to fight gravity, which came up and seized her like a dragon and brought her to the bottom", he wrote.

Spacetime and relativity (special relativity, general relativity)/gravity

 * Template:Relativity
 * Special relativity: Background, Fundamental concepts, Formulation, Phenomena, Spacetime
 * General relativity: Background, Fundamental concepts, Formulation, Phenomena, Advanced theories, Solutions
 * Scientists

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 * 
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 * Category:Spacetime


 * Spacetime: any mathematical model which fuses the three dimensions of space and the one dimension of time into a single four-dimensional manifold. The fabric of space-time is a conceptual model combining the three dimensions of space with the fourth dimension of time. Spacetime diagrams can be used to visualize relativistic effects, such as why different observers perceive differently where and when events occur.
 * Spacetime diagram: graphical illustration of the properties of space and time in the special theory of relativity. Spacetime diagrams allow a qualitative understanding of the corresponding phenomena like time dilation and length contraction without mathematical equations. The most well-known class of spacetime diagrams are known as Minkowski diagrams, developed by Hermann Minkowski in 1908.
 * Minkowski space (Minkowski spacetime): combination of three-dimensional Euclidean space and time into a four-dimensional manifold where the spacetime interval between any two events is independent of the inertial frame of reference in which they are recorded. Although initially developed by mathematician Hermann Minkowski for Maxwell's equations of electromagnetism, the mathematical structure of Minkowski spacetime was shown to be implied by the postulates of special relativity.
 * The choice of metric signature: In general, but with several exceptions, mathematicians and general relativists prefer spacelike vectors to yield a positive sign, (− + + +), while particle physicists tend to prefer timelike vectors to yield a positive sign, (+ − − −). Authors covering several areas of physics, e.g. Steven Weinberg and Landau and Lifshitz ((− + + +) and (+ − − −) respectively) stick to one choice regardless of topic. Arguments for the former convention include "continuity" from the Euclidean case corresponding to the non-relativistic limit c → ∞. Arguments for the latter include that minus signs, otherwise ubiquitous in particle physics, go away.


 * Energy–momentum relation (relativistic dispersion relation): relativistic equation relating total energy (which is also called relativistic energy) to invariant mass (which is also called rest mass) and momentum. It is the extension of mass–energy equivalence for bodies or systems with non-zero momentum.


 * Anti-de Sitter space (AdSn): maximally symmetric Lorentzian manifold with constant negative scalar curvature. Willem de Sitter and Albert Einstein worked together closely in Leiden in the 1920s on the spacetime structure of the universe. Manifolds of constant curvature are most familiar in the case of two dimensions, where the elliptic plane or surface of a sphere is a surface of constant positive curvature, a flat (i.e., Euclidean) plane is a surface of constant zero curvature, and a hyperbolic plane is a surface of constant negative curvature. Einstein's general theory of relativity places space and time on equal footing, so that one considers the geometry of a unified spacetime instead of considering space and time separately. The cases of spacetime of constant curvature are de Sitter space (positive), Minkowski space (zero), and anti-de Sitter space (negative). As such, they are exact solutions of the Einstein field equations for an empty universe with a positive, zero, or negative cosmological constant, respectively.
 * De Sitter space (dSn): maximally symmetric Lorentzian manifold with constant positive scalar curvature. It is the Lorentzian analogue of an n-sphere (with its canonical Riemannian metric). The main application of de Sitter space is its use in general relativity, where it serves as one of the simplest mathematical models of the universe consistent with the observed accelerating expansion of the universe. More specifically, de Sitter space is the maximally symmetric vacuum solution of Einstein's field equations with a positive cosmological constant Λ (corresponding to a positive vacuum energy density and negative pressure). There is cosmological evidence that the universe itself is asymptotically de Sitter, i.e. it will evolve like the de Sitter universe in the far future when dark energy dominates.
 * De Sitter universe: cosmological solution to the Einstein field equations of general relativity, named after Willem de Sitter. It models the universe as spatially flat and neglects ordinary matter, so the dynamics of the universe are dominated by the cosmological constant, thought to correspond to dark energy in our universe or the inflaton field in the early universe. According to the models of inflation and current observations of the accelerating universe, the concordance models of physical cosmology are converging on a consistent model where our universe was best described as a de Sitter universe at about a time t=10⁻³³ seconds after the fiducial Big Bang singularity, and far into the future.


 * Relativity of simultaneity: concept that distant simultaneity – whether two spatially separated events occur at the same time – is not absolute, but depends on the observer's reference frame.


 * Postulates of special relativity: Albert Einstein's 1905 theory of special relativity is derived from first principles. Einstein's formulation only uses two postulates, though his derivation implies a few more assumptions:
 * The laws of physics take the same form in all inertial frames of reference (principle of relativity).
 * As measured in any inertial frame of reference, light is always propagated in empty space with a definite velocity c that is independent of the state of motion of the emitting body. Or: the speed of light in free space has the same value c in all inertial frames of reference (invariance of c).


 * World line.svg
 * Light cone: path that a flash of light, emanating from a single event (localized to a single point in space and a single moment in time) and traveling in all directions, would take through spacetime.


 * Lorentz transform of world line.gif
 * World line: object is the path that object traces in 4-dimensional spacetime. It is an important concept in modern physics, and particularly theoretical physics.


 * Twin paradox: thought experiment in special relativity involving identical twins, one of whom makes a journey into space in a high-speed rocket and returns home to find that the twin who remained on Earth has aged more. This result appears puzzling because each twin sees the other twin as moving, and so, as a consequence of an incorrect and naive application of time dilation and the principle of relativity, each should paradoxically find the other to have aged less. However, this scenario can be resolved within the standard framework of special relativity: the travelling twin's trajectory involves two different inertial frames, one for the outbound journey and one for the inbound journey. Another way of looking at it is by realising that the travelling twin is undergoing acceleration, which makes him a non-inertial observer . In both views there is no symmetry between the spacetime paths of the twins. Therefore, the twin paradox is not a paradox in the sense of a logical contradiction.


 * Gravitational time dilation: form of time dilation, an actual difference of elapsed time between two events as measured by observers situated at varying distances from a gravitating mass. The lower the gravitational potential (the closer the clock is to the source of gravitation), the slower time passes, speeding up as the gravitational potential increases (the clock getting away from the source of gravitation). Albert Einstein originally predicted this effect in his theory of relativity and it has since been confirmed by tests of general relativity.

Books:
 * Gravitation (book) (1973, 2017; by Charles W. Misner, Kip S. Thorne, John Archibald Wheeler): MTW uses the $$- + + +$$ sign convention, and dissuades the use of the $$+ + + +$$ metric and imaginary time coordinate $$ict$$.
 * The Large Scale Structure of Space-Time (1973; by physicist Stephen Hawking & mathematician George Ellis)

People:
 * Hermann Minkowski (1864.06.22–1909.01.12): mathematician and professor at Königsberg, Zürich and Göttingen. In different sources Minkowski's nationality is variously given as German, Polish, or Lithuanian-German, or Russian. He created and developed the geometry of numbers and used geometrical methods to solve problems in number theory, mathematical physics, and the theory of relativity. Minkowski is perhaps best known for his work in relativity, in which he showed in 1907 that his former student Albert Einstein's special theory of relativity (1905) could be understood geometrically as a theory of four-dimensional space–time, since known as the "Minkowski spacetime".

Earth sciences

 * Category:Earth sciences
 * Category:Cartography


 * Earth science (geoscience, the geosciences or the Earth sciences)


 * Hydronym: proper name of a body of water. Hydronymy is the study of hydronyms and of how bodies of water receive their names and how they are transmitted through history. It can apply to rivers, lakes, and even oceanic elements. More than most toponyms, as linguistic items hydronyms are very conservative, with successor peoples often retaining the name given a body of water (e.g. Mississippi has passed from Native Americans to contemporary Americans (and then to other languages)). The names of large rivers are especially conserved, while the local names of small streams are less so.

Water bodies
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 * Meromictic lake: has layers of water that do not intermix

Places on Earth
Template:World geologic provinces
 * Geologic province (geologic or geomorphic province)

Impacts on Earth

 * Category:Impact craters on Earth
 * Category:Lists of impact craters on Earth
 * Category:Earth Impact Database

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 * List of impact craters on Earth
 * Earth Impact Database: database of confirmed impact structures or craters on Earth. It was initiated in 1955 by the Dominion Observatory, Ottawa, under the direction of Carlyle S. Beals. Since 2001, it has been maintained as a not-for-profit source of information at the Planetary and Space Science Centre at the University of New Brunswick, Canada.


 * List of possible impact structures on Earth: More than 130 geophysical features on the surface of the Earth have been proposed as candidate sites for impact events by appearing several times in the literature and/or being endorsed by the Impact Field Studies Group (IFSG) and/or Expert Database on Earth Impact Structures (EDEIS). For the purposes of this list and the List of impact craters on Earth, the terminology of "confirmed" as defined by the Earth Impact Database (EID) is considered authoritative.
 * Nastapoka arc: distinctively arcuate segment of the coastline of the southeastern shore of Hudson Bay in Quebec, Canada, that extends from the most northerly of the Hopewell Islands to Long Island near the junction with James Bay. It is a prominent, near-perfect circular arc, covering more than 160° of a 450-km-diameter circle.

Paleontology

 * Category:Paleontology


 * Paleontology: scientific study of life existent prior to, but sometimes including, the start of the Holocene Epoch. Includes the study of fossils to determine organisms' evolution and interactions with each other and their environments (their paleoecology). Paleontology lies on the border between biology and geology, but differs from archaeology in that it excludes the study of morphologically modern humans.

Geology

 * Category:Geology
 * Category:Subfields of geology
 * Category:Geochemistry
 * Category:Geophysics
 * Category:Radiometric dating
 * Category:Structural geology


 * Category:Historical geology
 * Category:Geological history of Earth
 * Category:Supercontinents
 * Category:Afro-Eurasia
 * Category:Americas
 * Category:Oceania


 * List of important publications in geology: Foundations. Economic geology. Geochemistry. Geochronology. Geomorphology. Geophysics. Geotechnical engineering. Hydrogeology. Mineralogy and petrology. Petroleum geology. Plate tectonics. Sedimentology and stratigraphy. Structural geology. Paleontology. Seismology. Tectonics. Volcanology.


 * Geology: science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which they change.
 * The principle of Uniformitarianism
 * The principle of intrusive relationships
 * The principle of cross-cutting relationships
 * The principle of inclusions and components
 * The principle of original horizontality
 * The principle of superposition
 * The principle of faunal succession


 * Goldschmidt classification: developed by Victor Goldschmidt, is a geochemical classification which groups the chemical elements according to their preferred host phases:
 * Lithophile elements (rock-loving): strong affinity for oxygen, most lithophile elements are enriched in the Earth's crust relative to their abundance in the solar system; phosphorus and the heavier halogens are probably significantly depleted on Earth as a whole relative to their solar abundances.
 * Siderophile elements (iron-loving): high-density transition metals which tend to sink into the core because they dissolve readily in iron either as solid solutions or in the molten state. Most siderophile elements have practically no affinity whatsoever for oxygen.
 * Chalcophile elements (ore-loving or chalcogen-loving): remain on or close to the surface because they combine readily with sulfur and/or some other chalcogen other than oxygen, forming compounds which do not sink into the core.
 * Atmophile (gas-loving) or volatile elements: element, or a compound in which it occurs, is liquid or gaseous at ambient surface conditions. H, C, N and noble gases.

Volcanology, vulcanology
Category:Petrology
 * Category:Igneous petrology
 * Category:Volcanology
 * Category:Volcanism
 * Category:Volcanoes
 * Category:Supervolcanoes
 * Category:Structural geology
 * Category:Tectonics
 * Category:Plate tectonics
 * Category:Earth's crust

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 * Volcanology (vulcanology): study of volcanoes, lava, magma and related geological, geophysical and geochemical phenomena (volcanism). Latin word vulcan. Vulcan was the ancient Roman god of fire.


 * Hotspot (geology): volcanic locales thought to be fed by underlying mantle that is anomalously hot compared with the surrounding mantle. Examples include the Hawaii, Iceland and Yellowstone hotspots. A hotspot's position on the Earth's surface is independent of tectonic plate boundaries, and so hotspots may create a chain of volcanoes as the plates move above them. There are two hypotheses that attempt to explain their origins. One suggests that hotspots are due to mantle plumes that rise as thermal diapirs from the core–mantle boundary. The alternative plate theory is that the mantle source beneath a hotspot is not anomalously hot, rather the crust above is unusually weak or thin, so that lithospheric extension permits the passive rising of melt from shallow depths.


 * Pangaea (Pangea): supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from earlier continental units during the Carboniferous approximately 335 million years ago, and began to break apart about 200 million years ago, at the end of the Triassic and beginning of the Jurassic. In contrast to the present Earth and its distribution of continental mass, Pangaea was centred on the Equator and surrounded by the superocean Panthalassa and the Paleo-Tethys and subsequent Tethys Oceans. Pangaea is the most recent supercontinent to have existed and the first to be reconstructed by geologists.

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 * VEIfigure en.svg
 * Volcanic Explosivity Index (VEI)


 * Supervolcano: large volcano that has had an eruption with VEI of 8, the largest recorded value on the index. This means the volume of deposits for that eruption is greater than 1,000 cubic kilometers.
 * Oruanui eruption: of New Zealand's Taupo Volcano, the world's most recent supereruption, had VEI of 8. It is one of the largest eruptions in the history of New Zealand. It occurred about 26,500 years ago in the Late Pleistocene and generated approximately 430 km³ of pyroclastic fall deposits, 320 km³ of pyroclastic density current (PDC) deposits (mostly ignimbrite) and 420 km³ of primary intracaldera material, equivalent to 530 km³ of magma, totaling 1,170 km³ of total deposits.
 * Lake Toba: large natural lake in North Sumatra, Indonesia, occupying the caldera of a supervolcano. The lake is about 100 km long, 30 km wide, and up to 505 m deep. It is the largest lake in Indonesia and the largest volcanic lake in the world .
 * Toba catastrophe theory: Youngest Toba eruption was a supervolcanic eruption that occurred around 75,000 years ago at the site of present-day Lake Toba in Sumatra, Indonesia. It is one of the Earth's largest known explosive eruptions. The Toba catastrophe theory holds that this event caused a global volcanic winter of six to ten years and possibly a 1,000-year-long cooling episode . In 1993, science journalist Ann Gibbons posited that a population bottleneck occurred in human evolution about 70,000 years ago, and she suggested that this was caused by the eruption. The Youngest Toba eruption is the most closely studied supervolcanic eruption. Volcanic winter and global cooling computer models: Physical data contradicting the winter hypothesis. Genetic bottleneck theory: Genetic bottleneck in humans; Genetic bottlenecks in other mammals. Migration after Toba: Analyses of mitochondrial DNA have estimated that the major migration from Africa occurred 60,000–70,000 years ago, consistent with dating of the Youngest Toba eruption to around 75,000 years ago.


 * List of largest volcanic eruptions: volcanic eruption, lava, volcanic bombs and ash, and various gases are expelled from a volcanic vent and fissure. While many eruptions only pose dangers to the immediately surrounding area, Earth's largest eruptions can have a major regional or even global impact, with some affecting the climate and contributing to mass extinctions. Volcanic eruptions can generally be characterized as either explosive eruptions, sudden ejections of rock and ash, or effusive eruptions, relatively gentle outpourings of lava.


 * Siberian Traps (Сибирские траппы): large region of volcanic rock, known as a large igneous province; massive eruptive event that formed the Traps is one of the largest-known volcanic events that has occurred in the last 500 Ma. The eruptions continued for roughly two Ma and spanned the P–T boundary . The Siberian Traps are believed to be the primary cause of the Permian–Triassic extinction event, the most severe extinction event in the geologic record.

Earthquakes:
 * Earthquake rupture: extent of slip that occurs during an earthquake in the Earth's crust. Earthquakes occur for many reasons that include: landslides, movement of magma in a volcano, the formation of a new fault, or, most commonly of all, a slip on an existing fault.
 * Earthquake light: luminous aerial phenomenon that reportedly appears in the sky at or near areas of tectonic stress, seismic activity, or volcanic eruptions. There is no broad consensus as to the causes of the phenomenon (or phenomena) involved. The phenomenon differs from disruptions to electrical grids – such as arcing power lines – which can produce bright flashes as a result of ground shaking or hazardous weather conditions.
 * Megathrust earthquakes: occur at convergent plate boundaries, where one tectonic plate is forced underneath another. The earthquakes are caused by slip along the thrust fault that forms the contact between the two plates. These interplate earthquakes are the planet's most powerful, with moment magnitudes (Mw) that can exceed 9.0. Since 1900, all earthquakes of magnitude 9.0 or greater have been megathrust earthquakes.


 * Ring of Fire (Pacific Ring of Fire): region around much of the rim of the Pacific Ocean where many volcanic eruptions and earthquakes occur. The Ring of Fire is a horseshoe-shaped belt about 40,000 km long and up to about 500 km wide.
 * Alpide belt (Alpine-Himalayan orogenic belt): seismic and orogenic belt that includes an array of mountain ranges extending for more than 15,000 kilometres along the southern margin of Eurasia, stretching from Java and Sumatra, through the Indochinese Peninsula, the Himalayas and Transhimalayas, the mountains of Iran, Caucasus, Anatolia, the Mediterranean, and out into the Atlantic. It is the second most seismically active region in the world, after the circum-Pacific belt (the Ring of Fire), with 17% of the world's largest earthquakes.

Stratigraphy

 * Category:Stratigraphy


 * Stratigraphy: branch of geology which studies rock layers (strata) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks.

Atmospheric sciences, atmosphere

 * Category:Atmospheric thermodynamics
 * Category:Atmosphere of Earth
 * Category:Atmospheric sciences
 * Category:Meteorology
 * Category:Branches of meteorology
 * Category:Tropical meteorology
 * Category:Types of cyclone
 * Category:Tropical cyclones
 * Category:Tropical cyclones by strength 1÷5
 * Category:Meteorological phenomena
 * Category:Atmospheric electricity
 * Category:Lightning


 * Terrestrial gamma-ray flash (TGF): burst of gamma rays produced in Earth's atmosphere. TGFs have been recorded to last 0.2 to 3.5 ms, and have energies of up to 20 MeV. It is speculated that TGFs are caused by intense electric fields produced above or inside thunderstorms. Scientists have also detected energetic positrons and electrons produced by terrestrial gamma-ray flashes.
 * Ball lightning: rare and unexplained phenomenon described as luminescent, spherical objects that vary from pea-sized to several meters in diameter. Though usually associated with thunderstorms, the observed phenomenon is reported to last considerably longer than the split-second flash of a lightning bolt, and is a phenomenon distinct from St. Elmo's fire. Characteristics: Odors resembling ozone, burning sulphur, or nitrogen oxides are often reported; Their diameters range from 1–100 cm, most commonly 10–20 cm; A wide range of colors has been observed, with red, orange, and yellow being the most common. Direct measurements of natural ball lightning. Laboratory experiments.


 * Storm surge (storm flood, tidal surge, or storm tide): coastal flood or tsunami-like phenomenon of rising water commonly associated with low-pressure weather systems, such as cyclones. It is measured as the rise in water level above the normal tidal level, and does not include waves. The main meteorological factor contributing to a storm surge is high-speed wind pushing water towards the coast over a long fetch. Other factors affecting storm surge severity include the shallowness and orientation of the water body in the storm path, the timing of tides, and the atmospheric pressure drop due to the storm. Most casualties during tropical cyclones occur as the result of storm surges and surges are a major source of damage to infrastructure and property during storms . Some theorize that as extreme weather becomes more intense and sea level rises due to climate change, storm surge is expected to cause more risk to coastal populations.


 * North Sea flood of 1953: major flood caused by a heavy storm at the end of Saturday, 1953.01.31 and morning of the next day. The storm surge struck the Netherlands, north-west Belgium, England and Scotland. A combination of a high spring tide and a severe European windstorm over the North Sea caused a storm tide. The combination of wind, high tide, and low pressure caused the sea to flood land up to 5.6 m above mean sea level. Most sea defences facing the surge were overwhelmed, causing extensive flooding. Responses: In the Netherlands the government conceived and constructed an ambitious flood defence system beginning in the 1960s. Called the Delta Works (Dutch: Deltawerken), it is designed to protect the estuaries of the rivers Rhine, Meuse and Scheldt. The system was completed in 1998, with completion of the storm surge barrier Maeslantkering in the Nieuwe Waterweg, near Rotterdam. In the UK, the Permanent Secretary to the Home Office, Sir Frank Newsam, coordinated the immediate efforts to defend homes, save lives and recover after the floods. After the flooding, the government made major investments in new sea defences. The Thames Barrier programme was started to secure Central London against a future storm surge; the Barrier was officially opened 1984.05.08. A range of flood defence measures were initiated around the UK coast.




 * List of Category 5 Atlantic hurricanes: tropical cyclone that reaches Category 5 intensity on the Saffir–Simpson hurricane wind scale, within the Atlantic Ocean to the north of the equator. They are among the strongest tropical cyclones that can form on Earth, having 1-minute sustained wind speeds of at least 254 km/h (70 m/s). The USA National Hurricane Center currently estimates that a total of 37 tropical cyclones between 1851 and 2021 have peaked as Category 5 hurricanes.
 * List of Category 4 Atlantic hurricanes: Category 4 hurricanes that later attained Category 5 strength are not included in this list. The Atlantic basin includes the open waters of the Atlantic Ocean, the Caribbean Sea and the Gulf of Mexico. Based on the Atlantic hurricane database, 142 hurricanes have attained Category 4 hurricane status since 1851, the start of modern meteorological record keeping. Category 4 storms are considered extreme hurricanes.


 * High-frequency Active Auroral Research Program (HAARP): original purpose was to analyze the ionosphere and investigate the potential for developing ionospheric enhancement technology for radio communications and surveillance. Since 2015 it has been operated by the University of Alaska Fairbanks. The most prominent instrument at HAARP is the Ionospheric Research Instrument (IRI), a high-power radio frequency transmitter facility operating in the high frequency (HF) band. The IRI is used to temporarily excite a limited area of the ionosphere. Other instruments, such as a VHF and a UHF radar, a fluxgate magnetometer, a digisonde (an ionospheric sounding device), and an induction magnetometer, are used to study the physical processes that occur in the excited region. HAARP is a target of conspiracy theorists, who claim that it is capable of "weaponizing" weather. Conspiracy theories: Journalist Sharon Weinberger called HAARP "the Moby Dick of conspiracy theories," and said the popularity of conspiracy theories often overshadows the benefits HAARP may provide to the scientific community.

Historical geology

 * Category:Historical geology


 * Supercontinent: assembly of most or all of Earth's continental blocks or cratons to form a single large landmass. However, the definition of a supercontinent can be ambiguous. Many earth scientists use the term supercontinent to mean "a clustering of nearly all continents".
 * Supercontinent cycle: quasi-periodic aggregation and dispersal of Earth's continental crust. There are varying opinions as to whether the amount of continental crust is increasing, decreasing, or staying about the same, but it is agreed that the Earth's crust is constantly being reconfigured. One complete supercontinent cycle is said to take 300 to 500 million years. The most recent supercontinent, Pangaea, formed about 300 million years ago. There are two different views on the history of earlier supercontinents. Because the oldest seafloor material found today dates to only 170 million years old, whereas the oldest continental crust material found today dates to at least 4 billion years old, it makes sense to emphasize the much longer record of the planetary pulse that is recorded in the continents. Relation to evolution: A north–south arrangement of continents and oceans leads to much more diversity and isolation than east–west arrangements.

Geochronology and chronostratigraphy

 * Category:Geochronology
 * Category:Geochronological dating methods
 * Category:Radiometric dating


 * Geologic time scale & Template:Geologic time scale: provides a system of chronologic measurement relating stratigraphy to time that is used by geologists, paleontologists and other earth scientists to describe the timing and relationships between events that have occurred during the history of the Earth.
 * Chronostratigraphy: branch of stratigraphy that studies the age of rock strata in relation to time. Ultimate aim of chronostratigraphy is to arrange the sequence of deposition and the time of deposition of all rocks within a geological region, and eventually, the entire geologic record of the Earth.
 * Geochronology: science of determining the age of rocks, fossils, and sediments, within a certain degree of uncertainty inherent to the method used.
 * Chronostratigraphy vs geochronology: chronostratigraphic units are geological material (layers of different (visual, chemical...) rocks); geochronological units are periods of time . Periods of time and the rock layers (strata, segments of rock) have the same names, but different unit names, Template:Geology to Paleobiology:
 * Geochronology: Eon (4, ~>500 Ma) > Era (12, ~>100 Ma) > Period > Epoch (~>10 Ma) > Age (~>1 Ma)
 * Chronostratigraphy: Eonothem (4, ~>500 Ma) > Erathem (12, ~>100 Ma) > System > Series (~>10 Ma) > Stage (~>1 Ma)
 * Global Standard Stratigraphic Age (GSSA): used primarily for time dating of rock layers older than 630 mya, before a good fossil record exists  (Precambrian). There is a gap between the last GSSP (542 mya) and the first GSSA (630 mya). List of GSSAs.
 * List of Global Boundary Stratotype Sections and Points: Global Boundary Stratotype Sections and Points (abbreviated GSSPs) are internationally agreed upon stratigraphic sections of rock which serve as references for boundaries on the geologic time scale. Starts at the earliest Cambrian (542.0±1.0 mya; when diverse hard-shelled animals first appeared), i.e. includes the whole Phanerozoic Eon.
 * Precambrian: Supereon from the formation of Earth to the Cambrian.
 * Cambrian: from 542±0.3 to 488.3±1.7 mya. Cambrian has unusually high proportion of lagerstätten (sites of exceptional preservation, where 'soft' parts of organisms are preserved as well as their more resistant shells):
 * Template:Cambrian explosion graphical timeline & Cambrian explosion (Cambrian radiation): relatively short evolutionary event, beginning around 542 Mya in the Cambrian Period, during which most major animal phyla appeared, as indicated by the fossil record. Lasting for about the next 20 My, it resulted in the origin of the body plan of modern metazoans.
 * Template:Cambrian preservational modes (Modes of preservation in the Cambrian)
 * International Union of Geological Sciences (IUGS):
 * International Commission on Stratigraphy (ICS, aka "International Stratigraphic Commission"), largest subcommittee of IUGS.


 * Lead–lead dating: method for dating geological samples, normally based on 'whole-rock' samples of material such as granite. For most dating requirements it has been superseded by uranium–lead dating (U–Pb dating), but in certain specialized situations (such as dating meteorites and the age of the Earth) it is more important than U–Pb dating.
 * Uranium–lead dating (U–Pb dating): one of the oldest and most refined of the radiometric dating schemes. It can be used to date rocks that formed and crystallised from about 1 million years to over 4.5 billion years ago with routine precisions in the 0.1–1 % range. The method is usually applied to zircon. This mineral incorporates uranium and thorium atoms into its crystal structure, but strongly rejects lead when forming. As a result, newly-formed zircon deposits will contain no lead, meaning that any lead found in the mineral is radiogenic. Since the exact rate at which uranium decays into lead is known, the current ratio of lead to uranium in a sample of the mineral can be used to reliably determine its age. Undamaged zircon retains the lead generated by radioactive decay of uranium and thorium up to very high temperatures (about 900 °C), though accumulated radiation damage within zones of very high uranium can lower this temperature substantially. Zircon is very chemically inert and resistant to mechanical weathering—a mixed blessing for geochronologists, as zones or even whole crystals can survive melting of their parent rock with their original uranium-lead age intact. Zircon crystals with prolonged and complex histories can thus contain zones of dramatically different ages (usually, with the oldest and youngest zones forming the core and rim, respectively, of the crystal), and thus are said to demonstrate inherited characteristics.

Geological eras

 * Category:Geological eras

{q.v. }
 * 


 * Cenozoic (Age of Mammals; 66.0 – 0 Ma)
 * Quaternary (2.588 – 0 Ma): current and most recent of the three periods of the Cenozoic Era in the geologic time scale of ICS.
 * Holocene (0.0117 – 0 Ma) ↓
 * Meghalayan (0.0042 – 0 Ma) ↓
 * Pleistocene (Ice Age; 2.58 – 0.0117 Ma) ↓
 * Tertiary widely used but obsolete term for the geologic period 66.0 – 2.6 Ma.
 * Neogene (informally Upper Tertiary or Late Tertiary; 23.03 – 2.58 Ma)
 * Paleogene (Palæogene, informally Lower Tertiary or Early Tertiary; 66.0 – 23.03 Ma): beginning of the Cenozoic Era of the present Phanerozoic Eon.
 * Mesozoic (Age of Reptiles, Age of Conifers; 251.902 ± 0.024 – 66.0 Ma)
 * Paleozoic (541.0 ± 1.0 – 251.902 ± 0.024 Ma)


 * Phanerozoic Eon (541.0 ± 1.0 – 0 Ma): current geologic eon in the geologic time scale, and the one during which abundant animal and plant life has existed; began with the Cambrian Period when animals first developed hard shells preserved in the fossil record. The time before the Phanerozoic, called the Precambrian, is now divided into the Hadean, Archaean and Proterozoic eons. The time span of the Phanerozoic starts with the sudden appearance of fossilized evidence of a number of animal phyla; the evolution of those phyla into diverse forms; the emergence and development of complex plants; the evolution of fish; the emergence of insects and tetrapods; and the development of modern fauna. Plant life on land appeared in the early Phanerozoic eon. During this time span, tectonic forces which move the continents had collected them into a single landmass known as Pangaea (the most recent supercontinent), which then separated into the current continental landmasses.
 * Cenozoic
 * Mesozoic
 * Paleozoic

Deep Earth

 * Category:Structure of the Earth
 * Category:Lithosphere Earth's lithosphere, other planetary bodies' lithospheres
 * Category:Earth's crust


 * Earth radius (R🜨 or $$R_E$$): distance from the center of Earth to a point on or near its surface. Approximating the figure of Earth by an Earth spheroid, the radius ranges from a maximum of nearly 6,378 km (equatorial radius, denoted a) to a minimum of nearly 6,357 km (polar radius, denoted b).


 * Lithosphere (λίθος 'rocky', and σφαίρα 'sphere'): rigid, outermost rocky shell of a terrestrial planet or natural satellite. On Earth, it is composed of the crust and the lithospheric mantle, the topmost portion of the upper mantle that behaves elastically on time scales of up to thousands of years or more.
 * Earth's lithosphere


 * Internal structure of Earth: solid portion of the Earth,[clarification needed] excluding its atmosphere and hydrosphere. The structure consists of an outer silicate solid crust, a highly viscous asthenosphere and solid mantle, a liquid outer core whose flow generates the Earth's magnetic field, and a solid inner core.
 * Crust and lithosphere
 * Mantle
 * Core: outer core is a fluid layer about 2,400 km thick [37% of the radius, 15.6% of the volume] and composed of mostly iron and nickel that lies above Earth's solid inner core and below its mantle. Inner core was discovered in 1936 by Inge Lehmann and is generally composed primarily of iron and some nickel. Since this layer is able to transmit shear waves (transverse seismic waves), it must be solid. Experimental evidence has at times been inconsistent with current crystal models of the core. Under laboratory conditions a sample of iron–nickel alloy was subjected to the corelike pressures by gripping it in a vise between 2 diamond tips (diamond anvil cell), and then heating to approximately 4000 K. The sample was observed with x-rays, and strongly supported the theory that Earth's inner core was made of giant crystals running north to south.
 * South Atlantic Anomaly: area where the Earth's inner Van Allen radiation belt comes closest to the Earth's surface


 * Earth's crust: less than 1% of Earth's radius and volume. It is the top component of the lithosphere, a division of Earth's layers that includes the crust and the upper part of the mantle. The lithosphere is broken into tectonic plates whose motion allows heat to escape from the interior of the Earth into space. The crust lies on top of the mantle, a configuration that is stable because the upper mantle is made of peridotite and is therefore significantly denser than the crust. The boundary between the crust and mantle is conventionally placed at the Mohorovičić discontinuity, a boundary defined by a contrast in seismic velocity. The crust of Earth is of two distinct types: 1. Oceanic: 5 km to 10 km thick and composed primarily of denser, more mafic rocks, such as basalt, diabase, and gabbro. 2. Continental: 30 km to 50 km thick and mostly composed of less dense, more felsic rocks, such as granite. In a few places, such as the Tibetan Plateau, the Altiplano, and the eastern Baltic Shield, the continental crust is thicker (50 km to 80 km).
 * Abundance of elements in Earth's crust: Most Abundant Elements of Earth's Crust by mass%: O (47%), Si (28%), Al (8%), Fe (5%), Ca (3-4%), Na (2.3-2.7%), K (2.1-2.6%), Mg (1.5-2.3%), Ti (0.44-0.57%), H (0.14%), P (0.10-0.11%), Mn (0.10%).


 * Mohorovičić discontinuity (Moho): boundary between the Earth's crust and the mantle; defined by the distinct change in velocity of seismic waves as they pass through changing densities of rock. The Moho lies almost entirely within the lithosphere (the hard outer layer of the Earth, including the crust). Only beneath mid-ocean ridges does it define the lithosphere–asthenosphere boundary (the depth at which the mantle becomes significantly ductile). The Mohorovičić discontinuity is 5 to 10 km below the ocean floor, and 20 to 90 km beneath typical continental crusts, with an average of 35 km.


 * Asthenosphere (ἀσθενός 'without strength'): mechanically weak and ductile region of the upper mantle of Earth. It lies below the lithosphere, at a depth between ~80 and 200 km below the surface, and extends as deep as 700 km. However, the lower boundary of the asthenosphere is not well defined. The asthenosphere is almost solid, but a slight amount of melting (less than 0.1% of the rock) contributes to its mechanical weakness. More extensive decompression melting of the asthenosphere takes place where it wells upwards, and this is the most important source of magma on Earth. It is the source of mid-ocean ridge basalt (MORB) and of some magmas that erupted above subduction zones or in regions of continental rifting.


 * Salt dome: a type of structural dome formed when a thick bed of evaporite minerals (mainly salt, or halite) found at depth intrudes vertically into surrounding rock strata, forming a diapir (salt is less dense than the surrounding strata under high pressure and therefore "floats" up (has increased buoyancy)); important in petroleum geology because salt structures are impermeable and can lead to the formation of a stratigraphic trap.
 * Salt glacier: flow of salt (typically halite) that is created when a rising diapir in a salt dome breaches the surface.

Sea/ocean floor drilling (with ships):
 * Deep Sea Drilling Program (DSDP; 1968-1983): ocean drilling project; provided crucial data to support the seafloor spreading hypothesis and helped to prove the theory of plate tectonics; for oil and gas exploration ; Messinian salinity crisis - 5.96-5.33 Ma multiple partly/nearly complete desiccation of the Mediterranean Sea to produce lots of salt. Ship: Glomar Challenger.
 * Ocean Drilling Program (ODP; 1985-2004): ship: JOIDES Resolution; climate change cycles, frozen methane hydrates, microbial community deep within the oceanic crust, fluids circulating through the ocean floor, formation of gigantic volcanic plateaus.
 * Integrated Ocean Drilling Program (IDOP; 2003-2013?): lead agencies: Japan's MEXT and USA's NSF; associates: PRC, South Korea, India, others. Ships: JOIDES Resolution (riserless), Chikyū (riser-equipped, deepest drill of 7,740 m).


 * Kola Superdeep Borehole (Кольская сверхглубокая скважина): result of a scientific drilling project of USSR in the Pechengsky District, on the Kola Peninsula. Project attempted to drill as deep as possible into the Earth's crust. Drilling began in 1970.05.24 using the Uralmash-4E, and later the Uralmash-15000 series drilling rig. A number of boreholes were drilled by branching from a central hole. The deepest, SG-3, reached 12,262 m in 1989 and still is the deepest artificial point on Earth. Because of higher-than-expected temperatures at this depth and location, 180 °C instead of expected 100 °C, drilling deeper was deemed infeasible and the drilling was stopped in 1992. To scientists, one of the more fascinating findings to emerge from this well is that no transition from granite to basalt was found at the depth of about 7 km, where the velocity of seismic waves has a discontinuity; instead the change in the seismic wave velocity is caused by a metamorphic transition in the granite rock; the rock at that depth had been thoroughly fractured and was saturated with water, which was surprising.

Climate

 * Category:Climatology
 * Category:Climate

{q.v. }
 * 


 * Climate




 * Antarctic ice sheet: covers about 98% of the Antarctic continent and is the largest single mass of ice on Earth. It covers an area of almost 14 million km² and contains 26.5 million km³ of ice. In East Antarctica, the ice sheet rests on a major land mass, while in West Antarctica the bed can extend to more than 2,500 m below sea level. Satellite measurements by NASA indicate a still increasing sheet thickness above the continent, outweighing the losses at the edge. The reasons for this are not fully understood, but suggestions include the climatic effects on ocean and atmospheric circulation of the ozone hole, and/or cooler ocean surface temperatures as the warming deep waters melt the ice shelves. History: The icing of Antarctica began in the middle Eocene about 45.5 mln. years ago and escalated during the Eocene–Oligocene extinction event about 34 mya. CO₂ levels were then about 760 ppm and had been decreasing from earlier levels in the thousands of ppm. Carbon dioxide decrease, with a tipping point of 600 ppm, was the primary agent forcing Antarctic glaciation.
 * Greenland ice sheet: vast body of ice covering 1,710,000 km², roughly 79% of the surface of Greenland. Second largest ice body in the world, after the Antarctic ice sheet. The ice sheet is almost 2,900 km long in a north–south direction, and its greatest width is 1,100 km at a latitude of 77°N, near its northern margin. The mean altitude of the ice is 2,135 m. The thickness is generally more than 2 km and over 3 km at its thickest point. In addition to the large ice sheet, smaller ice caps (such as Maniitsoq and Flade Isblink) as well as glaciers, cover between 76,000 and 100,000 km² around the periphery. If the entire 2,850,000 km³ of ice were to melt, it would lead to a global sea level rise of 7.2 m. Change of the ice sheet: The ice sheet as a record of past climates; General considerations on ice melting; General considerations on rate of change; Observation and research since 2010; Glacial calving 2000–2015; Twenty-first century melting events.

Global warming:
 * West Antarctic Ice Sheet: in the last 50 years the ice amount in Antarctica is decreasing. Why? Is it a normal fluctuation over 10k y. or not?
 * Runaway climate change
 * Clathrate gun hypothesis
 * Coral bleaching
 * Shutdown of thermohaline circulation: hypothesized effect of global warming on a major ocean circulation.
 * Arctic sea ice decline: occurred in recent decades by sea ice in the Arctic Ocean melting faster than it refreezes in the winter. The IPCC's Fourth Assessment Report (2007) stated that greenhouse gas forcing is predominantly responsible for the decline in Arctic sea ice extent.
 * Batagaika crater: thermokarst depression in the Chersky Range area. The biggest permafrost crater in the world, it administratively belongs to the Sakha Republic Russia and is in its Verkhoyansky District. The depression is in the form of a one-kilometre-long gash up to 100 metres deep, and growing. According to research published in 2016, the crater wall has been growing by a yearly average of 10 meters per year over a ten-year observational period.

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 * Tipping points in the climate system: threshold that, when exceeded, leads to large and often irreversible changes in the state of the system. Tipping points have been identified in the physical climate system and in ecosystems, which will have severe impacts on humans when crossed. Tipping points may be crossed even at a moderate increase of global temperature of 1.5–2 °C over pre-industrial times, due to current global warming. Climate scientists have identified over a dozen possible tipping points. If the tipping point in one system is crossed, this could lead to a cascade of other tipping points. One of these cascades could take the world into a greenhouse Earth state 4 or 5 degrees Celsius above pre-industrial levels.


 * Circum-Arctic Map of Permafrost and Ground Ice Conditions.png


 * 2003 European heat wave: hottest summer on record in Europe since at least 1540; c. 70k people died, mostly elderly. FR was affected the worst.


 * Great Frost of 1709: as it was known in England, or Le Grand Hiver ("The Great Winter"), as it was known in France, was an extraordinarily cold winter in Europe in late 1708 and early 1709, and was the coldest European winter during the past 500 years. The severe cold occurred during the time of low sunspot activity known as the Maunder Minimum . William Derham recorded in Upminster, near London, a low of −12 °C on the night of 5 January 1709, the lowest he had ever measured since he started taking readings in 1697. His contemporaries in the weather observation field in Europe likewise recorded lows down to −15 °C. Derham wrote in Philosophical Transactions: "I believe the Frost was greater (if not more universal also) than any other within the Memory of Man." During the Great Northern War, the Swedish invasion of Russia led by Charles XII of Sweden against Russia's Peter the Great was notably weakened by the severe winter. Sudden winter storms and frosts killed thousands during the Swedish army's winter offensives, most noticeably during a single night away from camp that killed at least 2,000. Because the Russian troops were more prepared for the harmful weather and cautiously stayed within their camps, their losses were substantially lower, contributing heavily to their eventual victory at Poltava the following summer. France was particularly hard hit by the winter, with the subsequent famine estimated to have caused 600,000 deaths by the end of 1710. Because the famine occurred during War of the Spanish Succession, there were contemporary nationalist claims that there were no deaths from starvation in the kingdom of France in 1709. European Union Millennium Project: Modern climate models do not appear to be entirely effective for explaining the climate of 1709.




 * Holocene (0.0117 – 0 Ma): current geological epoch began approximately 11,650 cal years BP, after the last glacial period, which concluded with the Holocene glacial retreat. The Holocene has been identified with the current warm period, known as MIS 1. It is considered by some to be an interglacial period within the Pleistocene Epoch, called the Flandrian interglacial. The Holocene corresponds with the rapid proliferation, growth and impacts of the human species worldwide, including all of its written history, technological revolutions, development of major civilizations, and overall significant transition towards urban living in the present. The human impact on modern-era Earth and its ecosystems may be considered of global significance for the future evolution of living species, including approximately synchronous lithospheric evidence, or more recently hydrospheric and atmospheric evidence of the human impact. In July 2018, the International Union of Geological Sciences split the Holocene epoch into three distinct subsections, Greenlandian (11,700 years ago to 8,200 years ago), Northgrippian (8,200 years ago to 4,200 years ago) and Meghalayan (4,200 years ago to the present), as proposed by ICS.
 * Meghalayan (0.0042 – 0 Ma): latest age or uppermost stage of the Quaternary. The age began with a 200-year drought that impacted human civilizations in the Eastern Mediterranean, Mesopotamia, the Indus Valley and the Yangtze River Valley. "The fact that the beginning of this age coincides with a cultural shift caused by a global climate event makes it unique," according to Stanley Finney, Secretary General of the International Union of Geological Sciences.
 * 4.2-kiloyear event (4.2-kiloyear BP aridification event): one of the most severe climatic events of the Holocene epoch. It defines the beginning of the current Meghalayan age in the Holocene epoch. Starting around 2200 BC, it probably lasted the entire 22nd century BC. It has been hypothesised to have caused the collapse of the Old Kingdom in Egypt as well as the Akkadian Empire in Mesopotamia, and the Liangzhu culture in the lower Yangtze River area. The drought may also have initiated the collapse of the Indus Valley Civilisation, with some of its population moving southeastward to follow the movement of their desired habitat, as well as the migration of Indo-European-speaking people into India.
 * 8.2 kiloyear event: sudden decrease in global temperatures that occurred approximately 8,200 years before the present, or c. 6,200 BCE, and which lasted for the next two to four centuries. Milder than the Younger Dryas cold spell that preceded it, but more severe than the Little Ice Age that would follow, the 8.2 kiloyear cooling was a significant exception to general trends of the Holocene climatic optimum.
 * Younger Dryas (c. 12,900 - c. 11,700 BP; YD): sharp decline in temperature over most of the northern hemisphere, at the end of the Pleistocene epoch, immediately preceding the current warmer Holocene. It was the most recent and longest of several interruptions to the gradual warming of the Earth's climate since the severe Last Glacial Maximum; period of climatic change, but the effects were complex and variable.
 * Younger Dryas impact hypothesis ((YDIH), Clovis comet hypothesis): speculative attempt to explain the onset of YD as an alternative to the long standing and widely accepted cause due to a significant reduction or shutdown of the North Atlantic "Conveyor" in response to a sudden influx of fresh water from Lake Agassiz and deglaciation in North America. The YDIH posits that fragments of a large (more than 4 kilometers in diameter), disintegrating asteroid or comet struck North America, South America, Europe, and western Asia around 12,850 years ago, coinciding with the beginning of the Younger Dryas cooling event. Multiple meteor air bursts and/or impacts are said to have produced the Younger Dryas boundary layer (YDB), depositing peak concentrations of platinum, high-temperature spherules, meltglass, and nanodiamonds, forming an isochronous datum at more than 50 sites across about 50 million km2 of Earth's surface. Some scientists have proposed that this event triggered extensive biomass burning, a brief impact winter and the Younger Dryas abrupt climate change, contributed to extinctions of late Pleistocene megafauna, and resulted in the end of the Clovis culture. A group known as the Comet Research Group are the primary advocates for the impact hypothesis, though other groups have published supporting evidence.
 * Channeled Scablands: relatively barren and soil-free region of interconnected relict and dry flood channels, coulees and cataracts eroded into Palouse loess and the typically flat-lying basalt flows that remain after cataclysmic floods within the southeastern part of Washington. The Channeled Scablands were scoured by more than 40 cataclysmic floods during the Last Glacial Maximum and innumerable older cataclysmic floods over the last two million years.
 * Missoula floods: cataclysmic glacial lake outburst floods that swept periodically across eastern Washington and down the Columbia River Gorge at the end of the last ice age. These floods were the result of periodic sudden ruptures of the ice dam on the Clark Fork River that created Glacial Lake Missoula.


 * Pleistocene (Ice Age; 2.58 – 0.0117 Ma): geological epoch spanning the world's most recent period of repeated glaciations. Before a change finally confirmed in 2009 by the International Union of Geological Sciences, the cutoff of the Pleistocene and the preceding Pliocene was regarded as being 1.806 million years BP. Publications from earlier years may use either definition of the period. The end of the Pleistocene corresponds with the end of the last glacial period and also with the end of the Paleolithic age used in archaeology.
 * Last Glacial Period (LGP): occurred from the end of the Eemian to the end of the Younger Dryas, encompassing the period c. 115,000 – c. 11,700 years ago. The LGP is part of a larger sequence of glacial and interglacial periods known as the Quaternary glaciation which started around 2,588,000 years ago and is ongoing. From the point of view of human archaeology, the LGP falls in the Paleolithic and early Mesolithic periods. When the glaciation event started, Homo sapiens was confined to lower latitudes and used tools comparable to those used by Neanderthals in western and central Eurasia and by Denisovans and Homo erectus in Asia. Near the end of the event, H. sapiens migrated into Eurasia and Australia. Archaeological and genetic data suggest that the source populations of Paleolithic humans survived the LGP in sparsely wooded areas, and dispersed through areas of high primary productivity, while avoiding dense forest cover.
 * Late Glacial Maximum (c. 13,000-10,000 years ago): defined primarily by the beginning of the modern warm period, in which climates in the Northern Hemisphere warmed substantially, causing a process of accelerated deglaciation following the Last Glacial Maximum.
 * Last Glacial Maximum: last period in the Earth's climate history during the last glacial period when ice sheets were at their greatest extension. Growth of the ice sheets reached their maximum positions 26,500 years ago. Deglaciation commenced in the Northern Hemisphere approximately 19,000 years ago, and in Antarctica approximately 14,500 years ago which is consistent with evidence that this was the primary source for an abrupt rise in the sea level 14,500 years ago. At this time, vast ice sheets covered much of North America, northern Europe and Asia.
 * Sundaland: biogeographical region of South-eastern Asia corresponding to a larger landmass that was exposed throughout the last 2.6 million years during periods when sea levels were lower. It includes Borneo, Java, and Sumatra in Indonesia, and their surrounding small islands, as well as the Malay Peninsula on the Asian mainland.


 * Pleistocene megafauna: set of large animals that lived on Earth during the Pleistocene epoch. Pleistocene megafauna became extinct during the Quaternary extinction event resulting in substantial changes to ecosystems globally. The role of humans in causing Pleistocene megafaunal extinctions is controversial. Extinction causes: Four theories have been advanced as likely causes of these extinctions: hunting by the spreading humans (or overkill hypothesis, initially developed by geoscientist Paul S. Martin), the change in climate at the end of the last glacial period, disease, and an extraterrestrial impact from an asteroid or comet. These factors are not necessarily exclusive: any or all may have combined to cause the extinctions.


 * Bond event: North Atlantic ice rafting events that are tentatively linked to climate fluctuations in the Holocene. Eight such events have been identified. Bond events were previously believed to exhibit a roughly c. 1,500-year cycle, but the primary period of variability is now put at c. 1,000 years.


 * Paleocene–Eocene Thermal Maximum (PETM, "Eocene thermal maximum 1" (ETM1); 55.0 mln ya): most extreme change in Earth surface conditions during the Cenozoic Era began just after the temporal boundary between the Paleocene and Eocene epochs; rapid (in geological terms) global warming, profound changes in ecosystems, and major perturbations in the carbon cycle. Global temperatures rose by about 6 °C over a period of approximately 20,000 years.


 * Quaternary extinction event (from 2.588 ± 0.005 million years ago to the present): the extinctions of numerous predominantly megafaunal species, which have resulted in a collapse in faunal density and diversity and the extinction of key ecological strata across the globe. The most prominent event in the Late Pleistocene is differentiated from previous Quaternary pulse extinctions by the widespread absence of ecological succession to replace these extinct species, and the regime shift of previously established faunal relationships and habitats as a consequence. The earliest casualties were incurred at 130,000 BCE (the start of the Late Pleistocene), in Australia ~ 60,000 years ago, in Americas ~ 15,000 years ago, coinciding in time with the early human migrations. However, the great majority of extinctions in Afro-Eurasia and the Americas occurred during the transition from the Pleistocene to the Holocene epoch (13,000 BCE to 8,000 BCE).
 * Holocene extinction (Anthropocene extinction): ongoing extinction event during the Holocene epoch. The extinctions span numerous families of bacteria, fungi, plants, and animals, including mammals, birds, reptiles, amphibians, fish, invertebrates, and affecting not just terrestrial species but also large sectors of marine life. With widespread degradation of biodiversity hotspots, such as coral reefs and rainforests, as well as other areas, the vast majority of these extinctions are thought to be undocumented, as the species are undiscovered at the time of their extinction, which goes unrecorded. The current rate of extinction of species is estimated at 100 to 1,000 times higher than natural background extinction rates, and is increasing. During the past 100–200 years, biodiversity loss and species extinction have accelerated, to the point that most conservation biologists now believe that humankind has either entered a period of mass extinction, or is on the cusp of doing so.

Climate change

 * Category:Climate change
 * Category:Climate change and the environment
 * Category:Climate change mitigation
 * Category:Climate change policy

{q.v. }





Politics:
 * 2015 United Nations Climate Change Conference: held in Paris, France 2015.11.30-12.12. It was the 21st yearly session of the Conference of the Parties to the 1992 United Nations Framework Convention on Climate Change (UNFCCC) and the 11th session of the Meeting of the Parties to the 1997 Kyoto Protocol. Limit the temperature increase to 1.5°C. Such an ambitious goal would require a zero level in emissions sometimes between 2030 and 2050 . However, no concrete goals for emissions were stated in the final version of the Paris Agreement.
 * Paris Agreement:


 * Global dimming: first systematic measurements of global direct irradiance at the Earth's surface began in the 1950s. A decline in irradiance was soon observed, and it was given the name of global dimming. It continued from 1950s until 1980s, with an observed reduction of 4–5% per decade, even though solar activity did not vary more than the usual at the time. Global dimming has instead been attributed to an increase in atmospheric particulate matter, predominantly sulfate aerosols, as the result of rapidly growing air pollution due to post-war industrialization . After 1980s, global dimming started to reverse, alongside reductions in particulate emissions, in what has been described as global brightening, although this reversal is only considered "partial" for now. The reversal has also been globally uneven, as the dimming trend continued during the 1990s over some mostly developing countries like India, Zimbabwe, Chile and Venezuela. Over China, the dimming trend continued at a slower rate after 1990, and did not begin to reverse until around 2005. Global dimming has interfered with the hydrological cycle by lowering evaporation, which is likely to have reduced rainfall in certain areas, and may have caused the observed southwards shift of the entire tropical rain belt between 1950 and 1985, with a limited recovery afterwards. Since high evaporation at the tropics is needed to drive the wet season, cooling caused by particulate pollution appears to weaken Monsoon of South Asia, while reductions in pollution strengthen it. Multiple studies have also connected record levels of particulate pollution in the Northern Hemisphere to the monsoon failure behind the 1984 Ethiopian famine, although the full extent of anthropogenic vs. natural influences on that event is still disputed. On the other hand, global dimming has also counteracted some of the greenhouse gas emissions, effectively "masking" the total extent of global warming experienced to date, with the most-polluted regions even experiencing cooling in the 1970s. Conversely, global brightening had contributed to the acceleration of global warming which began in the 1990s . Climate models are broadly capable of simulating the impact of aerosols like sulfates, and in the IPCC Sixth Assessment Report, they are believed to offset around 0.5 °C of warming. Likewise, climate change scenarios incorporate reductions in particulates and the cooling they offered into their projections, and this includes the scenarios for climate action required to meet 1.5 °C and 2 °C targets. It is generally believed that the cooling provided by global dimming is similar to the warming derived from atmospheric methane, meaning that simultaneous reductions in both would effectively cancel each other out. However, uncertainties remain about the models' representation of aerosol impacts on weather systems, especially over the regions with a poorer historical record of atmospheric observations.

Ice ages

 * Category:Ice ages
 * Category:Cryogenian


 * Snowball Earth: geohistorical hypothesis that proposes during one or more of Earth's icehouse climates, the planet's surface became entirely or nearly entirely frozen with no liquid oceanic or surface water exposed to the atmosphere. The most academically referred period of such global glaciation is believed to have occurred sometime before 650 mya during the Cryogenian period. A number of unanswered questions remain, including whether Earth was a full snowball or a "slushball" with a thin equatorial band of open (or seasonally open) water. The snowball-Earth episodes are proposed to have occurred before the sudden radiation of multicellular bioforms known as the Cambrian explosion. The most recent snowball episode may have triggered the evolution of multicellularity.

Geography

 * Category:Geography
 * Category:Branches of geography
 * Category:Cartography
 * Category:Geographic data and information
 * Category:Geographical technology
 * Category:Geographic information systems
 * Category:Navigation
 * Category:History of navigation
 * Category:Satellite navigation
 * Category:Landforms
 * Category:Continents


 * Continents by colour.png
 * Continental models-Australia.gif


 * Continent: one of several large landmasses. Generally identified by convention rather than any strict criteria, up to seven regions are commonly regarded as continents. Ordered from largest in area to smallest, these seven regions are: Asia, Africa, North America, South America, Antarctica, Europe, and Australia. Variations with fewer continents may merge some of these, for example some systems include Eurasia or America as single continents. Oceanic islands are frequently grouped with a neighbouring continent to divide all the world's land into regions. Under this scheme, most of the island countries and territories in the Pacific Ocean are grouped together with the continent of Australia to form a region called Oceania.


 * Longitude rewards: system of inducement prizes offered by the British government for a simple and practical method for the precise determination of a ship's longitude at sea. The rewards, established through an Act of Parliament (the Longitude Act) in 1714, were administered by the Board of Longitude. This was by no means the first reward to be offered to solve this problem. Philip II of Spain offered one in 1567, Philip III in 1598 offered 6,000 ducats and a pension, whilst the States General of the Netherlands offered 10,000 florins shortly after. However, these large sums were never won, though several people were awarded smaller amounts for significant achievements. John Harrison's contested reward: H4 sea watch. Harrison was 21 years old when the Longitude Act was passed. He spent the next 45 years perfecting the design of his timekeepers. He first received a reward from the Commissioners of Longitude in 1737 and did not receive his final payment until he was 80.
 * Marine chronometer: timepiece that is precise and accurate enough to be used as a portable time standard; it can therefore be used to determine longitude by means of celestial navigation. When first developed in the 18th century, it was a major technical achievement, as accurate knowledge of the time over a long sea voyage is necessary for navigation, lacking electronic or communications aids. The first true chronometer was the life work of one man, John Harrison, spanning 31 years of persistent experimentation and testing that revolutionized naval (and later aerial) navigation and enabling the Age of Discovery and Colonialism to accelerate.


 * Terra Australis


 * Mediterranean sea (oceanography): mostly enclosed sea that has limited exchange of water with outer oceans and where the water circulation is dominated by salinity and temperature differences rather than winds. E.g. Baltic Sea, Mediterranean Sea, Arctic Ocean; Red Sea, Persian Gulf; Australasian Mediterranean Sea.


 * Baltic Sea: was known in ancient sources as Mare Suebicum or Mare Germanicum. In the Middle Ages the sea was known by variety of names. The name Baltic Sea became dominant only after 1600. Usage of Baltic and similar terms to denote the region east of the sea started only in 19th century.


 * Satellite navigation (SAT NAV; global navigation satellite system (GNSS)): system is a system of satellites that provide autonomous geo-spatial positioning with global coverage. It allows small electronic receivers to determine their location (longitude, latitude, and altitude) to within a few metres using time signals transmitted along a line-of-sight by radio from satellites.
 * Global Positioning System (GPS): USA; free to use for civilian needs.
 * Dilution of precision (GPS) (DOP; geometric dilution of precision (GDOP)): term used in GPS and geomatics engineering to specify the additional multiplicative effect of GPS satellite geometry on GPS precision.
 * GLONASS (ГЛОНАСС): RU SAT NAV. Began in 1976 by USSR. In 2000s (decade) under Putin's presidency GLONASS was restored and by 2010 GLONASS covered 100% of RU; in 2011.10 24 satellites were restored enabling full coverage . The most expensive project by RU's Federal Space Agency. Free for civilians. Main reason for restoration: during 2008 South Ossetia war GPS was blacked out in the region. iPhone 4S supports both GPS & GLONASS.
 * Beidou navigation system (BeiDou (Compass) Navigation Satellite System): project by China/PRC to develop an independent SAT NAV. Operational in 2011.12 with coverage over PRC and neighbors with 10 satellites.
 * Galileo (satellite navigation): EU's SAT NAV. €20 bln. 2 satellites on 2011.10.21. In total 30 satellites by the earliest 2019-2020. Free for civilian use; special encrypted band for the commercial purposes for fee.
 * Regional SAT NAVs: Indian Regional Navigational Satellite System (IRNSS): first satellite to be launched in 2012-2013.

Physical geography, cartography

 * Category:Physical geography
 * Category:Biogeography
 * Category:Cartography
 * Category:Collaborative mapping
 * Category:Geographic information systems
 * Category:Maps
 * Category:Web mapping
 * Category:Climate
 * Category:Geographic data and information
 * Category:Web mapping
 * Category:Maps

{q.v. }
 * User:Kazkaskazkasako/Books/EECS
 * User:Kazkaskazkasako/Books/EECS


 * Cartography (from Greek χάρτης chartēs, "papyrus, sheet of paper, map"; and γράφειν graphein, "write"): study and practice of making maps. Combining science, aesthetics, and technique, cartography builds on the premise that reality can be modeled in ways that communicate spatial information effectively. Set the map's agenda and select traits of the object to be mapped; map projections; generalization; reduce the complexity of the characteristics that will be mapped; map design.
 * Cartographic generalization (map generalization): includes all changes in a map that are made when one derives a smaller-scale map from a larger-scale map or map data, or vice-versa. Whether done manually by a cartographer or by a computer or set of algorithms, generalization seeks to abstract spatial information at a high level of detail to information that can be rendered on a map at a lower level of detail. For example, we might have the outlines of all of the thousands of buildings in a region, but we wish to make a map of the whole city no more than a few inches wide. Instead of throwing out the building information, or trying to render it all at once, we could generalize the data into some sort of outline of the urbanized area of the region.
 * Map: symbolic depiction emphasizing relationships between elements of some space, such as objects, regions, or themes. Many maps are static, fixed to paper or some other durable medium, while others are dynamic or interactive. Although most commonly used to depict geography, maps may represent any space, real or fictional, without regard to context or scale, such as in brain mapping, DNA mapping, or computer network topology mapping. The space being mapped may be two dimensional, such as the surface of the earth, three dimensional, such as the interior of the earth, or even more abstract spaces of any dimension, such as arise in modeling phenomena having many independent variables. Although the earliest maps known are of the heavens, geographic maps of territory have a very long tradition and exist from ancient times. The word "map" comes from the medieval Latin Mappa mundi, wherein mappa meant napkin or cloth and mundi the world. {q.v. User:Kazkaskazkasako/Books/History @Mappa mundi} History of cartography. Geographic maps. Orientation of maps. Scale and accuracy. Symbology (Map symbol; Labeling). Map types: Electronic maps, Climatic maps, Non-geographical spatial maps, Topological maps, General-purpose maps.
 * Map projection: way to flatten a globe's surface into a plane in order to make a map. This requires a systematic transformation of the latitudes and longitudes of locations from the surface of the globe into locations on a plane. All projections of a sphere on a plane necessarily distort the surface in some way and to some extent. Depending on the purpose of the map, some distortions are acceptable and others are not; therefore, different map projections exist in order to preserve some properties of the sphere-like body at the expense of other properties. Every distinct map projection distorts in a distinct way, by definition. Projections by surface: Cylindrical, Pseudocylindrical, Hybrid, Conic, Pseudoconic, Azimuthal (projections onto a plane). Projections by preservation of a metric property: Equal-area, Equidistant, Gnomonic, Retroazimuthal, Compromise projections. Which projection is best?


 * Choropleth map (Greek χῶρος choros 'area/region' and πλῆθος plethos 'multitude'): type of thematic map in which a set of pre-defined areas is colored or patterned in proportion to a statistical variable that represents an aggregate summary of a geographic characteristic within each area, such as population density or per-capita income.


 * Geographic information system (GIS): system designed to capture, store, manipulate, analyze, manage, and present spatial or geographic data. GIS applications are tools that allow users to create interactive queries (user-created searches), analyze spatial information, edit data in maps, and present the results of all these operations. GIScience. GIS can refer to a number of different technologies, processes, techniques and methods. GIS can relate unrelated information by using location as the key index variable. Locations or extents in the Earth space–time may be recorded as dates/times of occurrence, and x, y, and z coordinates representing, longitude, latitude, and elevation, respectively. All Earth-based spatial–temporal location and extent references should be relatable to one another and ultimately to a "real" physical location or extent. This key characteristic of GIS has begun to open new avenues of scientific inquiry. History of development. Techniques and technology: Geoprocessing; Relating information from different sources; GIS uncertainties; Data representation (GIS file formats); Data capture; Raster-to-vector translation; Projections, coordinate systems, and registration (@Map projection). Spatial analysis with GIS: Slope and aspect, Data analysis, Topological modeling, Geometric networks, Hydrological modeling, Cartographic modeling, Map overlay, Geostatistics, Address geocoding, Reverse geocoding, Data output and cartography, Graphic display techniques, Spatial ETL, GIS data mining. Applications: Open Geospatial Consortium standards, @Web mapping, Adding the dimension of time. Semantics. Implications of GIS in society.


 * Template:Cartography topics:
 * By continent: Early world maps; Africa; Asia; Europe
 * By country or region
 * By city: Dublin; Jerusalem; York
 * History of cartography:
 * Ancient age: Ptolemy's world map; Soleto Map (Sec. V BC)
 * Middle age: Tabula Rogeriana (1154); Catalan Atlas (1375)
 * Modern age: Map of Juan de la Cosa (1500); Cantino planisphere (1502); Early modern Iberian cartography; Early modern Netherlandish cartography
 * Contemporary age: Cassini map

History of cartography

 * History of cartography: traces the development of cartography, or mapmaking technology, in human history. Maps have been one of the most important human inventions for millennia. People have created and used maps to help them define, explain, and navigate their way through the world. Earliest archaeological maps include cave paintings to ancient maps of Babylon, Greece, China, and India. They began as two-dimensional drawings, and for some time at least in Europe, the Earth was thought to be flat. Nowadays maps can be visualized adopted as three-dimensional shapes on globes. Modern maps of the old and new worlds developed through the Age of Discovery. Ancient Near East. Ancient Greece. Hellenistic Mediterranean. Roman Empire. China. India. Islamic cartographic schools (Arab and Persian cartography). Polynesian stick charts. Medieval Europe. Early modern cartography. Modern cartography. History of cartography's technological changes.

Ancient age:
 * Ptolemy's world map: map of the world known to Greco-Roman society in the 2nd century. It is based on the description contained in Ptolemy's book Geography, written c. 150. Based on an inscription in several of the earliest surviving manuscripts, it is traditionally credited to Agathodaemon of Alexandria. Notable features of Ptolemy's map is the first use of longitudinal and latitudinal lines as well as specifying terrestrial locations by celestial observations. The Geography was translated from Greek into Arabic in the 9th century and played a role in the work of al-Khwārizmī before lapsing into obscurity. The idea of a global coordinate system revolutionized European geographical thought, however, and inspired more mathematical treatment of cartography.

Middle age:

Modern age:
 * Cantino planisphere (Cantino world map): manuscript Portuguese world map preserved at the Biblioteca Estense in Modena, Italy. It is named after Alberto Cantino, an agent for the Duke of Ferrara, who successfully smuggled it from Portugal to Italy in 1502. It measures 220 x 105 cm. This planisphere is the earliest surviving map showing Portuguese geographic discoveries in the east and west, and is particularly notable for portraying a fragmentary record of the Brazilian coast, which the Portuguese explorer Pedro Álvares Cabral explored in 1500, and for depicting the African coast of the Atlantic and Indian Oceans with remarkable accuracy and detail.

Contemporary age:
 * Cassini map (map of the Academy): first topographic and geometric map established of the Kingdom of France as a whole. It was compiled by the Cassini family, mainly César-François Cassini (Cassini III) and his son Jean-Dominique Cassini (Cassini IV) in the 18th c.

Biogeography

 * Category:Biogeography
 * Category:Biogeographic realms
 * Category:Australasian realm {q.v. }


 * Biogeography: study of the distribution of species and ecosystems in geographic space and through geological time. Organisms and biological communities often vary in a regular fashion along geographic gradients of latitude, elevation, isolation and habitat area. Phytogeography is the branch of biogeography that studies the distribution of plants. Zoogeography is the branch that studies distribution of animals.


 * Template:Biomes


 * Terrestrial ecozone: broadest biogeographic division of the Earth's land surface, based on distributional patterns of terrestrial organisms; organisms have been evolving in relative isolation over long periods of time, separated from one another by geographic features, such as oceans, broad deserts, or high mountain ranges, that constitute barriers to migration. Ecozones (WWF definition): Palearctic (Eurasia + N. Africa), Nearctic (N. America), Afrotropic (Sub-Saharan Africa), Neotropic (S. and C. America), Australasia, Indo-Malaya (Indian subcontinent, SE Asia, Southern China), Oceania, Antarctic.


 * Map of Sunda and Sahul 2.png
 * Australasian realm: biogeographic realm that is coincident, but not synonymous (by some definitions), with the geographical region of Australasia. The realm includes Australia, the island of New Guinea (including Papua New Guinea and the Indonesian province of Papua), and the eastern part of the Indonesian archipelago, including the island of Sulawesi, the Moluccan islands (the Indonesian provinces of Maluku and North Maluku) and islands of Lombok, Sumbawa, Sumba, Flores, and Timor, often known as the Lesser Sundas. The Australasian realm also includes several Pacific island groups, including the Bismarck Archipelago, Vanuatu, the Solomon Islands, and New Caledonia. New Zealand and its surrounding islands are a distinctive sub-region of the Australasian realm. From an ecological perspective the Australasian realm is a distinct region with a common geologic and evolutionary history and a great many unique plants and animals.
 * Wallacea: biogeographical designation for a group of mainly Indonesian islands separated by deep water straits from the Asian and Australian continental shelves. Wallacea includes Sulawesi, the largest island in the group, as well as Lombok, Sumbawa, Flores, Sumba, Timor, Halmahera, Buru, Seram, and many smaller islands.
 * Wallace Line: faunal boundary line drawn in 1859 by the British naturalist Alfred Russel Wallace that separates the ecozones of Asia and Wallacea, a transitional zone between Asia and Australia. West of the line are found organisms related to Asiatic species; to the east, a mixture of species of Asian and Australian origin is present.


 * Indomalayan realm


 * Great American Interchange: important late Cenozoic paleozoogeographic event in which land and freshwater fauna migrated from North America via Central America to South America and vice versa, as the volcanic Isthmus of Panama rose up from the sea floor and bridged the formerly separated continents. Although there were earlier dispersals, probably over water, the migration accelerated dramatically about 2.7 Ma during the Piacenzian age. One living South American marsupial, the monito del monte, has been shown to be more closely related to Australian marsupials than to other South American marsupials; however, it is the most basal australidelphian, meaning that this superorder arose in South America and then colonized Australia after the monito del monte split off. The near-simultaneity of the megafaunal extinctions with the glacial retreat and the peopling of the Americas has led to proposals that both climate change and human hunting played a role. Similar megafaunal extinctions have occurred on other recently populated land masses (e.g. Australia, Japan, Madagascar, New Zealand, and many smaller islands around the world, such as Cyprus, Crete, Tilos and New Caledonia) at different times that correspond closely to the first arrival of humans at each location. The reason that a number of groups went extinct in North America but lived on in South America (while there are no examples of the opposite pattern) appears to be that the dense rainforest of the Amazon basin and the high peaks of the Andes provided environments that afforded a degree of protection from human predation.

Geocoding

 * Category:Geocodes
 * Category:Country codes


 * ISO 3166-1 alpha-3: three-letter country codes defined in ISO 3166-1. Most important ones: EU/Eu: AUT (Austria), BEL, BGR, CHE (Switzerland), DEU, ESP, EST, FRA, GBR, GRC (Greece), HRV, HUN, IRL, ITA, LTU, NLD, NOR (Norway), POL, ROU (Romania), RUS, SVK (Slovakia), SVN (Slovenia), SWE, UKR; Africa: EGY, ZAF (South Africa); Americas: CAN, USA; Asia: CHN, HKG, IDN (Indonesia), IND, ISR, JPN, MYS (Malaysia), PAK, TUR, TWN (Taiwan); Other: AUS, NZL.


 * List of international vehicle registration codes: displayed in bold block uppercase on a small white oval plate or sticker near the number plate on the rear of a vehicle. Many vehicle codes created since the adoption of ISO 3166 coincide with ISO two- or three-letter codes, exceptions (oldies): A (austria), B (Belgium), D (Germany), E (Spain), F (France), H (Hungary), P (Portugal), L (Luxembourg), S (Sweden), I (Italy), N (Norway), C (Cuba), V (Vatican), T (Thailand), K (Cambodia), J (Japan), Z (Zambia), M (Malta), Q (Qatar), G (Gabon)

Afro-Eurasia, Eurasia

 * Category:Afro-Eurasia
 * Category:Eurasia

Asia

 * Anatolia (Asia Minor; Ἀνατολή, Anatolḗ, meaning east or [sun]rise, Turkish: Anadolu; Asian Turkey, Anatolian peninsula): large peninsula in Western Asia and the westernmost protrusion of the Asian continent. It constitutes the majority of modern-day Turkey. The region is bounded by the Turkish Straits to the northwest, the Black Sea to the north, the Armenian Highlands to the east, the Mediterranean Sea to the south, and the Aegean Sea to the west. The Sea of Marmara forms a connection between the Black and Aegean seas through the Bosporus and Dardanelles straits and separates Anatolia from Thrace on the Balkan peninsula of Southeast Europe. The ancient Anatolian peoples spoke the now-extinct Anatolian languages of the Indo-European language family, which were largely replaced by the Greek language during the classical antiquity as well as during the Hellenistic, Roman, and Byzantine periods. The major Anatolian languages included Hittite, Luwian, and Lydian, while other, poorly attested local languages included Phrygian and Mysian. Hurro-Urartian languages were spoken in the southeastern kingdom of Mitanni, while Galatian, a Celtic language, was spoken in Galatia, central Anatolia. The Turkification of Anatolia began under the rule of the Seljuk Empire in the late 11th century and it continued under the rule of the Ottoman Empire between the late 13th and the early 20th century and it has continued under the rule of today's Republic of Turkey.

{q.v. User:Kazkaskazkasako/Books/History}

Europe

 * Modern Celts:
 * Brittany shouldn't be mixed with Normandy.


 * Normandy: named after the Vikings. Normandy was the area from which Norman conquest of England was carried out.
 * Cotentin Peninsula (Cherbourg Peninsula): in Normandy that forms part of the northwest coast of France. It extends north-westward into the English Channel, towards Great Britain. To its west lie the Channel Islands and to the southwest lies the peninsula of Brittany.
 * Channel Islands (Norman: Îles d'la Manche; French: îles Anglo-Normandes or îles de la Manche): archipelago in the English Channel, off the French coast of Normandy. They include two Crown dependencies: the Bailiwick of Jersey, which is the largest of the islands; and the Bailiwick of Guernsey, consisting of Guernsey, Alderney, Sark, Herm and some smaller islands. They are considered the remnants of the Duchy of Normandy and, although they are not part of UK, the UK is responsible for the defence and international relations of the islands. "Channel Islands" is a geographical term, not a political unit. The two bailiwicks have been administered separately since the late 13th century. Each has its own independent laws, elections, and representative bodies (although in modern times, politicians from the islands' legislatures are in regular contact). Any institution common to both is the exception rather than the rule.


 * Atlantropa (Panropa): was a gigantic engineering and colonisation idea devised by the German architect Herman Sörgel in the 1920s and promoted by him until his death in 1952. Its central feature was a hydroelectric dam to be built across the Strait of Gibraltar, which would have provided enormous amounts of hydroelectricity and would have led to the lowering of the surface of the Mediterranean Sea by up to 200 metres, opening up large new lands for settlement, for example in the Adriatic Sea. The project proposed four additional major dams as well: Across the Dardanelles to hold back the Black Sea; Between Sicily and Tunisia; On the Congo River below its Kwa River tributary to refill the Mega-Chad basin around Lake Chad providing fresh water to irrigate the Sahara and creating a shipping lane to the interior of Africa; Suez Canal extension and locks to maintain Red Sea connection.
 * Desertec: was a large scale project supported by a foundation of the same name and the consortium Dii (Desertec industrial initiative) created in Germany as GmbH. The project aimed at creating a global renewable energy plan based on the concept of harnessing sustainable power from sites where renewable sources of energy are more abundant and transferring it through high-voltage direct current transmission to consumption centers. All kinds of renewable energy sources are envisioned, but the sun-rich deserts of the world play a special role.
 * DESERTEC-Map large.jpg

Middle East

 * Category:Geography of the Middle East
 * Category:Mesopotamia
 * Category:Upper Mesopotamia

{q.v. User:Kazkaskazkasako/Books/History: history of Middle East}

Americas

 * Category:Americas

South America

 * Darién Gap: break in the Pan-American Highway consisting of a large swath of undeveloped swampland and forest within Panama's Darién Province in Central America and the northern portion of Colombia's Chocó Department in South America. The gap begins in Yaviza, Panama and ends in Turbo, Colombia, and is 106 km long. Roadbuilding through this area is expensive and the environmental cost is high. Political consensus in favor of road construction has not emerged. Consequently, there is no road connection through the Darién Gap connecting North America with South America and it is the missing link of the Pan-American Highway. Armed conflict and kidnappings: The Darién Gap was subject to the presence and activities of the Marxist Revolutionary Armed Forces of Colombia (FARC), which has committed assassinations, kidnappings and human rights violations during its decades-long insurgency against the Colombian government.

Antarctica

 * Category:Science and technology in Antarctica
 * Category:Astronomy in the Antarctic
 * Category:Antarctic research
 * Category:Outposts of Antarctica


 * Research stations in Antarctica: Many of the stations are staffed around the year. A total of 42 countries (as of October 2006), all signatories to the Antarctic Treaty, operate seasonal (summer) and year-round research stations on the continent. The population of people performing and supporting scientific research on the continent and nearby islands varies from approximately 4,000 during the summer season to 1,000 during winter (June).


 * Dome A: loftiest ice dome on the Antarctic Plateau, located 1,200 km inland. It is thought to be the coldest naturally occurring place on Earth; with temperatures believed to reach −90°C to −98°C. It is the highest ice feature in Antarctica, consisting of an ice dome or eminence of 4,093 m elevation above sea level. Exploration. Observatory
 * Ridge A: site in Antarctica that was identified in 2009 as the best suited location on the surface of Earth for astronomical research. The site, approximately 1,000 km from the South Pole and 144 km southeast of Dome A. The site is on the Antarctic Plateau at an altitude of 4,053 m, and has an average winter temperature of −70°C. It is possible that this site may have even lower temperatures than Dome A. Ridge A was identified by a team of Australian and American scientists searching for the best observatory spot in the world. The site represents the "Eye of the Storm", whereby winds flowing off Antarctica in all directions appear to start from a point at Ridge A, where winds are at their calmest. It is also the site of a vortex in which swirling stratospheric winds high up and calm air at ground level combine to make it a place for viewing into space that is three times clearer than any other location on Earth.


 * History of Antarctica

Oceania

 * Category:Oceania
 * Category:Regions of Oceania
 * Category:Melanesia
 * Category:Micronesia
 * Category:Polynesia
 * Australasia | Australasian realm {q.v. }


 * Oceanias Regions.png


 * Australasia: region which comprises Australia, New Zealand, and some neighbouring islands. The term is used in a number of different contexts including geopolitically, physiogeographically, and ecologically where the term covers several slightly different but related regions.




 * Melanesia: subregion of Oceania in the southwestern Pacific Ocean. It extends from the island of New Guinea in the west to Tonga in the east, and includes the Arafura Sea. The region includes the four independent countries of Fiji, Vanuatu, the Solomon Islands, and Papua New Guinea. It also includes the French colony of New Caledonia and parts of Indonesia – notably the occupied regions of Maluku Islands and Western New Guinea, which is often referred to as West Papua. East Timor is also often included. Almost all of the region is in the Southern Hemisphere; only a few small islands that are considered part of Oceania — specifically the northwestern islands of Western New Guinea — lie in the Northern Hemisphere.

Natural resources, resource extraction

 * Category:Energy production
 * Category:Fuel production
 * Category:Natural resources
 * Category:Resource extraction
 * Category:Mining
 * Category:Mining by mineral
 * Category:Coal mining
 * Category:History of primary sector industries
 * Category:History of agriculture
 * Category:Agricultural revolutions
 * Category:Intensive farming


 * Coal seam fire: underground smouldering of a coal deposit, often in a coal mine (due to human intervention or human factor); serious health and safety hazard as well as affecting the environment by releasing toxic fumes, reigniting grass, brush, or forest fires, and causing subsidence of surface infrastructure such as roads, pipelines, electric lines, bridge supports, buildings and homes. Because they burn underground, coal seam fires are extremely difficult and costly to extinguish, and are unlikely to be suppressed by rainfall. These fires are most acute in industrializing, coal-rich nations such as PRC.

Forest products

 * Category:Forest products
 * Category:Non-timber forest products


 * Creosote: category of carbonaceous chemicals formed by the distillation of various tars and pyrolysis of plant-derived material, such as wood or fossil fuel. They are typically used as preservatives or antiseptics. Some creosote types were used historically as a treatment for components of seagoing and outdoor wood structures to prevent rot (e.g., bridgework and railroad ties). Samples may be found commonly inside chimney flues, where the coal or wood burns under variable conditions, producing soot and tarry smoke. Creosotes are the principal chemicals responsible for the stability, scent, and flavor characteristic of smoked meat; the name is derived from Greek κρέας (kreas), meaning 'meat', and σωτήρ (sōtēr), meaning 'preserver'. The two main kinds recognized in industry are coal-tar creosote and wood-tar creosote. The coal-tar variety, having stronger and more toxic properties, has chiefly been used as a preservative for wood. Varieties of creosote have also been made from both oil shale and petroleum, and are known as oil-tar creosote when derived from oil tar, and as water-gas-tar creosote when derived from the tar of water gas. Creosote also has been made from pre-coal formations such as lignite, yielding lignite-tar creosote, and peat, yielding peat-tar creosote.

Environment

 * Category:Natural environment
 * Category:Environment and society

Environment and society: Man-made disasters, environmental issues/disasters, pollution

 * Category:Environment and society
 * Category:Environmental issues
 * Category:Environmental issues with soil
 * Category:Desertification
 * Category:Pollution
 * Category:Man-made disasters
 * Category:Environmental disasters
 * Category:Plastics and the environment

{q.v. }

"Pollute first, then clean up": a way from underdeveloped to the developed country. Questionable? Worst energy-generating polluters: Coal, oil, ..., nuclear. There are more deaths from renewables (flooding, damn building human deaths) than from nuclear accidents. And nuclear is held at much higher standard for waste disposal than burned waste derived from coal or oil. Persistent organic pollutants, forever chemicals (per- and polyfluoroalkyl substances), microsplastics, ...


 * Plastic pollution: accumulation of plastic objects and particles in the Earth's environment that adversely affects humans, wildlife and their habitat. Plastics that act as pollutants are categorized by size into micro-, meso-, or macro debris. Plastics are inexpensive and durable, making them very adaptable for different uses; as a result, manufacturers choose to use plastic over other materials. However, the chemical structure of most plastics renders them resistant to many natural processes of degradation and as a result they are slow to degrade. Together, these two factors allow large volumes of plastic to enter the environment as mismanaged waste and for it to persist in the ecosystem. As of 2020, the global mass of produced plastic exceeds the biomass of all land and marine animals combined. A May 2019 amendment to the Basel Convention regulates the exportation/importation of plastic waste, largely intended to prevent the shipping of plastic waste from developed countries to developing countries. Nearly all countries have joined this agreement.
 * Marine plastic pollution: plastic pollution in the ocean) is a type of marine pollution by plastics, ranging in size from large original material such as bottles and bags, down to microplastics formed from the fragmentation of plastic material. Marine debris is mainly discarded human rubbish which floats on, or is suspended in the ocean. Eighty percent of marine debris is plastic. Microplastics and nanoplastics result from the breakdown or photodegradation of plastic waste in surface waters, rivers or oceans. Recently, scientists have uncovered nanoplastics in heavy snow, more specifically about 3000 tons that cover Switzerland yearly. It is estimated that there is a stock of 86 million tons of plastic marine debris in the worldwide ocean as of the end of 2013, assuming that 1.4% of global plastics produced from 1950 to 2013 has entered the ocean and has accumulated there. It is estimated that 19–23 million tonnes of plastic leaks into aquatic ecosystems annually. The 2017 UN Ocean Conference estimated that the oceans might contain more weight in plastics than fish by the year 2050.


 * Microplastics: fragments of any type of plastic less than 5 mm in length, according to NOAA and the European Chemicals Agency. They enter natural ecosystems from a variety of sources, including cosmetics, clothing, and industrial processes. Primary microplastics include any plastic fragments or particles that are already 5.0 mm in size or less before entering the environment. These include microfibers from clothing, microbeads, and plastic pellets (also known as nurdles). Secondary microplastics arise from the degradation (breakdown) of larger plastic products through natural weathering processes after entering the environment. Such sources of secondary microplastics include water and soda bottles, fishing nets, plastic bags, microwave containers and tea bags. Both types are recognized to persist in the environment at high levels, particularly in aquatic and marine ecosystems. However, microplastics also accumulate in the air and terrestrial ecosystems. The term macroplastics is used to differentiate microplastics from larger plastic waste, such as plastic bottles. Because plastics degrade slowly (often over hundreds to thousands of years), microplastics have a high probability of ingestion, incorporation into, and accumulation in the bodies and tissues of many organisms. The toxic chemicals that come from both the ocean and runoff can also biomagnify up the food chain. In terrestrial ecosystems, microplastics have been demonstrated to reduce the viability of soil ecosystems and reduce weight of earthworms. The cycle and movement of microplastics in the environment are not fully known, but research is currently underway to investigate the phenomenon. Deep layer ocean sediment surveys in China (2020) show the presence of plastics in deposition layers far older than the invention of plastics, leading to suspected underestimation of microplastics in surface sample ocean surveys. The Ocean Conservancy has reported that China (PRC), Indonesia, Philippines, Thailand, and Vietnam dump more plastic in the sea than all other countries combined. China banned in 2018 the import of recyclables from other countries, forcing those other countries to re-examine their recycling schemes. The Yangtze River in China contributes 55% of all plastic waste going to the seas. Including microplastics, the Yangtze bears an average of 500,000 pieces of plastic per square kilometer. Scientific American reported that China dumps 30% of all plastics in the ocean. Where microplastics can be found: Oceans: Seabed; Ice Cores; Freshwater ecosystems; Soil; Human body; Air.
 * Tea bag (teabag): small, porous, sealed bag or packet, typically containing tea leaves or the leaves of other herbs, which is immersed in water to steep and make an infusion. Originally used only for tea (Camellia sinensis), they are now made with other tisanes ("herbal teas") as well. Plastics: Even before composting, microplastics may be found in the tea meant for human consumption. A 2019 study showed that "steeping a single plastic teabag at brewing temperature (95 °C) releases approximately 11.6 billion microplastics and 3.1 billion nanoplastics into a single cup of the beverage".
 * Plastisphere: refer to ecosystems that have evolved to live in human-made plastic environments. All the plastic that is accumulating in marine ecosystems serve as a habitat for various types of microorganisms. The use of plastic has increased twenty-fold since 1964, and it is expected to double by 2035. Despite efforts to implement recycling programs, recycling rates tend to be quite low. For instance, in the EU, only 29% of the plastic consumed is recycled. Plastic pollution acts as a more durable "ship" than biodegradable material for carrying the organisms over long distances. This long distance transportation can move microbes to different ecosystems and potentially introduce invasive species as well as harmful algae. The microorganisms found on the plastic debris include autotrophs, heterotrophs and symbionts. The ecosystem created by the plastisphere differs from other floating materials that naturally occur (i.e., feathers and algae) due to the slow speed of biodegradation and the different conditions. In addition to microbes, insects have come to flourish in areas of the ocean that were previously uninhabitable. The sea skater, for example, has been able to reproduce on the hard surface provided by the floating plastic. Degradation by microorganisms: On the other hand, as plastic is broken down into smaller pieces and eventually microplastics, there is a higher likelihood that it will be consumed by plankton and enter into the food chain. As plankton are eaten by larger organisms, the plastic may eventually cause there to be bioaccumulation in fish eaten by humans.
 * Plasticulture: practice of using plastic materials in agricultural applications. The plastic materials themselves are often and broadly referred to as "ag plastics". Plasticulture ag plastics include soil fumigation film, irrigation drip tape/tubing, plastic plant packaging cord, nursery pots and bales, but the term is most often used to describe all kinds of plastic plant/soil coverings. Such coverings range from plastic mulch film, row coverings, high and low tunnels (polytunnels), to plastic greenhouses. Plastic used in agriculture was expected to include 6.7 million tons of plastic in 2019 or 2% of global plastic production. Plastic used in agriculture is hard to recycle because of contamination by agricultural chemicals. Moreover, plastic degradation into microplastics is damaging to soil health, microorganisms and beneficial organism like earth worms.
 * Plastic mulch: product used in plasticulture in a similar fashion to mulch, to suppress weeds and conserve water in crop production and landscaping. Certain plastic mulches also act as a barrier to keep methyl bromide, both a powerful fumigant and ozone depleter, in the soil. Crops grow through slits or holes in thin plastic sheeting. Plastic mulch is often used in conjunction with drip irrigation.
 * Plasticosis: form of fibrotic scarring that is caused by small pieces of plastic which inflame the digestive tract. A 2023 study by Hayley Charlton-Howard, Alex Bond, Jack Rivers-Auty, and Jennifer Lavers, found that plastic pollution caused disease in seabirds. The researchers coined the term plasticosis to indicate the first recorded instance of plastic-induced fibrosis in wild animals. "Further, the ingestion of plastic has far-reaching and severe consequences, many of which we are only just beginning to fully document and understand." Plasticosis is a pathological wound healing in which connective tissue replaces normal parenchymal tissue to the extent that it goes unchecked, leading to considerable tissue remodelling and the formation of permanent scar tissue.
 * The Ocean Cleanup: nonprofit environmental engineering organization based in the Netherlands that develops technology to extract plastic pollution from the oceans and to capture it in rivers before it can reach the ocean. Their initial focus was on the Pacific Ocean and its garbage patch, and extended to rivers in countries including Indonesia, Guatemala, and USA.


 * Desertification


 * List of environmental disasters: Agricultural; Biodiversity; Human health; Industrial; Mining; Coal mining; Oil industry; Nuclear; Air/land/water


 * Persistent, bioaccumulative and toxic substances (PBTs): class of compounds that have high resistance to degradation from abiotic and biotic factors, high mobility in the environment and high toxicity. Because of these factors PBTs have been observed to have a high order of bioaccumulation and biomagnification, very long retention times in various media, and widespread distribution across the globe. Majority of PBTs in the environment are either created through industry or are unintentional byproducts.
 * Stockholm Convention on Persistent Organic Pollutants: international environmental treaty, signed in 2001 and effective from May 2004, that aims to eliminate or restrict the production and use of POPs.
 * Persistent organic pollutant (POPs, "forever chemicals"): organic compounds that are resistant to environmental degradation through chemical, biological, and photolytic processes. Because of their persistence, POPs bioaccumulate with potential adverse impacts on human health and the environment. The effect of POPs on human and environmental health was discussed, with intention to eliminate or severely restrict their production, by the international community at the Stockholm Convention on Persistent Organic Pollutants in 2001. Many POPs are currently or were in the past used as pesticides, solvents, pharmaceuticals, and industrial chemicals.
 * Per- and polyfluoroalkyl substances (PFASs, perfluorinated alkylated substances): synthetic organofluorine chemical compounds that have multiple fluorine atoms attached to an alkyl chain. As such, they contain at least one perfluoroalkyl moiety, –CnF2n–. They are more effective at reducing the surface tension of water than comparable hydrocarbon surfactants. They include the perfluorosulfonic acids such as the PFOS and the perfluorocarboxylic acids such as PFOA. PFOS and PFOA are persistent organic pollutants and are detected in humans and wildlife. Fluorosurfactants such as PFOS, PFOA, and PFNA have caught the attention of regulatory agencies because of their persistence, toxicity, and widespread occurrence in the blood of general populations and wildlife. In 2009, PFASs were listed as persistent organic pollutants under the Stockholm Convention, due to their ubiquitous, persistent, bioaccumulative, and toxic nature. The Devil We Know (2018), Dark Waters (2019).
 * Perfluorooctanesulfonic acid (PFOS; C₈HF₁₇O₃S, C8HF17O3S)
 * Perfluorooctanoic acid (PFOA; C₈HF₁₅O₂, C8HF15O2)
 * Perfluorononanoic acid (PFNA; C₉HF₁₇O₂, C9HF17O2)
 * Hexafluoro-2-propanol (CF3)2CHOH
 * Timeline of events related to per- and polyfluoroalkyl substances (PFASs): discovery, development, manufacture, marketing, uses, concerns, litigation, regulation, and legislation, involving the man-made PFASs, particularly PFOA and PFOS. and about the companies, mainly DuPont and 3M that manufactured and marketed them. PFAS are commonly found in every American household, and in products as diverse as non-stick cookware, stain resistant furniture and carpets, wrinkle free and water repellant clothing, cosmetics, lubricants, paint, pizza boxes, popcorn bags, and many other everyday products.
 * Polytetrafluoroethylene (Teflon): synthetic fluoropolymer of tetrafluoroethylene that has numerous applications. PTFE is a fluorocarbon solid (at room temperature), as it is a high molecular weight polymer consisting wholly of carbon and fluorine. PTFE is hydrophobic: neither water nor water-containing substances wet PTFE, as fluorocarbons demonstrate mitigated London dispersion forces due to the high electronegativity of fluorine. PTFE has one of the lowest coefficients of friction of any solid. PTFE is used as a non-stick coating for pans and other cookware. It is non-reactive, partly because of the strength of carbon–fluorine bonds, and so it is often used in containers and pipework for reactive and corrosive chemicals. Where used as a lubricant, PTFE reduces friction, wear, and energy consumption of machinery. It is commonly used as a graft material in surgical interventions. It is also frequently employed as coating on catheters; this interferes with the ability of bacteria and other infectious agents to adhere to catheters and cause hospital-acquired infections.


 * Hexavalent chromium (Cr(VI)): chromium in any chemical compound that contains the element in the +6 oxidation state (thus hexavalent). Virtually all chromium ore is processed via Cr(VI), specifically the salt sodium dichromate. Cr(VI) is key to all materials made from chromium. Approximately 136,000 t of Cr(VI) were produced in 1985. Cr(VI) is used in textile dyes, wood preservation, anti-corrosion products, chromate conversion coatings, and a variety of niche uses. Industrial uses of Cr(VI) compounds include chromate pigments in dyes, paints, inks, and plastics; chromates added as anticorrosive agents to paints, primers, and other surface coatings; and chromic acid electroplated onto metal parts to provide a decorative or protective coating. Cr(VI) can be formed when performing "hot work" such as welding on stainless steel or melting chromium metal. In these situations the chromium is not originally hexavalent, but the high temperatures involved in the process result in oxidation that converts the chromium to a hexavalent state. Cr(VI) can also be found in drinking water and public water systems. All Cr(VI) compounds are toxic (due to their oxidizing power) as well as carcinogenic (IARC Group 1), especially if airborne and inhaled where they cause lung cancer. Positive associations have also been observed between exposure to Cr(VI) compounds and cancer of the nose and nasal sinuses. Workers in many occupations are exposed to Cr(VI). Problematic exposure is known to occur among workers who handle chromate-containing products and those who grind and/ or weld stainless steel. Workers who are exposed to Cr(VI) are at increased risk of developing lung cancer, asthma, or damage to the nasal epithelia and skin. Toxicity: Due to its structural similarity to sulfate, chromate (a typical form of Cr(VI) at neutral pH) is transported into cells via sulfate channels. Inside the cell, Cr(VI) is reduced first to pentavalent Cr(V) then to trivalent Cr(III) without the aid of any enzymes. The reduction occurs via direct electron transfer primarily from ascorbate and some nonprotein thiols. Vitamin C and other reducing agents combine with chromate to give Cr(III) products inside the cell. The resultant Cr(III) forms stable complexes with nucleic acids and proteins. This causes strand breaks and Cr–DNA adducts which are responsible for mutagenic damage.
 * Hinkley groundwater contamination: from 1952 to 1966, Pacific Gas and Electric Company (PG&E) dumped about 1,400 mln L of chromium-tainted wastewater into unlined wastewater spreading ponds around the town of Hinkley, CA, USA, located in the Mojave Desert (about 120 miles north-northeast of LA). PG&E used Cr(VI) (a cheap and efficient rust suppressor) in its compressor station for natural-gas transmission pipelines. In 1993, legal clerk Erin Brockovich began an investigation into the health impacts of the contamination. A class-action lawsuit about the contamination was settled in 1996 for $333 million.
 * Chromium toxicity: any poisonous toxic effect in an organism or cell that results from exposure to specific forms of chromium—especially Cr(VI). Cr(VI) and its compounds are toxic when inhaled or ingested. Cr(III) is a trace mineral that is essential to human nutrition. There is a hypothetical risk of genotoxicity in humans if large amounts of Cr(III) were somehow able to enter living cells, but normal metabolism and cell function prevent this.
 * Chromium deficiency: described as the consequence of an insufficient dietary intake of the mineral chromium. Chromium was first proposed as an essential element for normal glucose metabolism in 1959, and was widely accepted as being such by the 1990s. Cases of deficiency were described in people who received all of their nutrition intravenously for long periods of time.

Industrial:
 * Love Canal: was a neighborhood in Niagara Falls, New York, located in the LaSalle section of the city. In the mid-1970s Love Canal became the subject of national and international attention after it was revealed in the press that the site had formerly been used to bury 21,000 tons of toxic waste by Hooker Chemical Company (now Occidental Petroleum Corporation). Hooker Chemical sold the site to the Niagara Falls School Board in 1953 for $1, with a deed explicitly detailing the presence of the waste, and including a liability limitation clause about the contamination. The construction efforts of housing development, combined with particularly heavy rainstorms, released the chemical waste, leading to a public health emergency and an urban planning scandal. Hooker Chemical was found to be negligent in their disposal of waste, though not reckless in the sale of the land, in what became a test case for liability clauses. "National symbol of a failure to exercise a sense of concern for future generations"; inhabitants "overflowed into the wastes instead of the other way around".


 * Hydrocarbons (oil industry):
 * List of oil spills
 * Deepwater Horizon explosion & Deepwater Horizon oil spill: in the Gulf of Mexico. Marine ecological catastrophy (fisheries closed, aquacultures perished, ocean floor full of oil, marine animals and mammals found dead); economic catastrophy (sand beaches full of oil, pollution of swimming water and air). BP created $20 bln spill response fund, around 100,000 claims; settling out of court through compensation.
 * Piper Alpha: began production in 1976, firstly as an oil platform, later converted to gas production. Gas explosion and resulting fire destroyed it on 6 July 1988. Hugest disaster of that time and in the North Sea.


 * Aliso Canyon gas leak (Porter Ranch gas leak): massive natural gas leak in the Santa Susana Mountains near Porter Ranch, LA, CA, USA. Discovered by SoCalGas employees in 2015.10.23, gas was escaping from a well within the Aliso Canyon underground storage facility. This second-largest gas storage facility of its kind in the United States belongs to the Southern California Gas Company, a subsidiary of Sempra Energy. In 2016.01.06, Governor Jerry Brown issued a state of emergency. The Aliso gas leak's carbon footprint is said to be larger than the Deepwater Horizon leak in the Gulf of Mexico. An estimated 97,100 t of methane and 7,300 t of ethane were released into the atmosphere.

Pollution in USA

 * [[File:Superfund sites.svg|thumb|400px|right|Map of Superfund sites in USA; Red indicates currently on final National Priority List, yellow is proposed, green is deleted (usually meaning having been cleaned up). US EPA [2010].]]
 * National Priorities List (NPL): list of hazardous waste sites in USA eligible for long-term remedial action (cleanup) financed under the federal Superfund program. EPA regulations outline a formal process for assessing hazardous waste sites and placing them on the NPL.
 * List of Superfund sites in the United States: polluted locations requiring a long-term response to clean up hazardous material contaminations.
 * Superfund (Comprehensive Environmental Response, Compensation, and Liability Act of 1980): USA federal law designed to clean up sites contaminated with hazardous substances as well as broadly defined "pollutants or contaminants". EPA may identify parties responsible for hazardous substances releases to the environment and compel those parties to clean up the sites, or it may cleanup itself using the Superfund (a trust fund) and cost recover from responsible parties by referring such matters to the U.S. Department of Justice.


 * Oakdale Dump: EPA Superfund site located in Oakdale, Minnesota, and comprises three non-contiguous properties that were used for dumping from the late 1940s until the 1950s by the 3M corporation. In September 1982, the Minnesota Mining and Manufacturing Company (3M) conducted excavation tests in the trenches at the Abresch site and buried drum stockpiles were identified. 3M commissioned a surface cleanup of wastes at the Abresch site beginning in the winter of 1983. During the excavation activities, a total of 11,500 cubic yards of waste material was removed including 4,200 empty drums, 8,700 empty 5-gallon pails, 4,660 cubic yards of contaminated soil, and 15 intact containers that were over-packed. Most of the waste, 11,800 tons, was transported to the 3M Chemolite incinerator in Cottage Grove, Minnesota. An additional 6,500 tons of excavated waste containing more than 50 ppm of PCBs were transported to a hazardous waste landfill for disposal.

Pollution in PRC (China), depletion of resources

 * Environment in the People's Republic of China: ancient forests, desertification
 * Environmental issues in China: soil and water,
 * Pollution in China: industrial pollution, air & water pollution: cancer is the leading cause of death
 * Electronic waste in Guiyu: largest e-waste site on Earth; no laws on import of e-waste


 * Water supply and sanitation in the People's Republic of China
 * Chinese water crisis
 * China Water Risk: non-profit initiative based in Hong Kong dedicated to highlighting and addressing business and environmental risk arising from the country’s water crisis. Its stated aim is "to foster efficient and responsible use of water resources of PRC by engaging the global investment and business communities, civil society and individuals in understanding and managing China’s water risk”. Key risks in China arising from water scarcity and pollution: China has 20% of the world’s population but only 7% of its freshwater reserves; Dry 11 of 31 regions of mainland China provinces (including Jiangsu, Shandong, Henan, Hebei, Shanxi, Beijing, Shanghai and Tianjin) have renewable resources per capita per annum below 1,000 m³; These Dry 11 have water resources comparable to the Middle East; Pollution exacerbates scarcity. 77% of the 26 key lakes and reservoirs and 43% of the 7 major river basins monitored are unfit for human contact. Already, 19% of rivers and basins and 35% of key lakes and reservoirs are essentially useless for both agricultural and industrial use.


 * Coal in China

Pollution in USSR, Russia

 * Lake Karachay: dumping site for radioactive waste (see also: Kyshtym disaster, Mayak Production Association)
 * Dzerzhinsk, Russia: city in Nizhny Novgorod Oblast, Russia, located along the Oka River, about 400 kilometers (250 mi) east of Moscow. Greenpeace: high levels of persistent organic chemicals, particularly dioxins; Blacksmith Institute: also sarin, lewisite, sulfur mustard, hydrogen cyanide, phosgene, lead, and organic chemicals among the worst pollutants (Dzerzhinsk is one of the worst-polluted cities of the world and has a life expectancy of 42 years for men and 47 for women, with the 2003 death rate exceeding its birth rate by 260%).
 * Derweze (The Gate; Darvaza. Turkmenistan): Derweze area is rich in natural gas. While drilling in 1971, Soviet geologists tapped into a cavern filled with natural gas; ground beneath the drilling rig collapsed, leaving a large hole with a diameter of 70 metres; it was decided the best solution was to burn it off; geologists had hoped the fire would use all the fuel in a matter of days, but the gas is still burning today; locals have dubbed the cavern "The Door to Hell".

Fisheries, world waters as food source
{q.v. User:Kazkaskazkasako/Books/All}


 * Category:Environmental impact of fishing


 * Harmful algal bloom: contains organisms that can severely lower oxygen levels in natural waters, killing marine life. Some HABs are associated with algae-produced toxins. Blooms can last from a few days to many months. After the bloom dies, the microbes which decompose the dead algae use up even more of the oxygen, which can create fish die-offs. When these zones of depleted oxygen cover a large area for an extended period of time, they are referred to as dead zones, where neither fish nor plants are able to survive. Types: Cyanobacteria; Red tides (diatoms, dinoflagellates). Causes: chemical wastes, primarily nutrients—phosphorus and nitrates. Harmful effects: Human health: Food, Drinking water; Economic impact: Recreation and tourism, Fisheries industry; Environmental impact: Increasing number and range, Fish die-offs, Land animal deaths, More dead zones.
 * Dead zone (ecology): hypoxic (low-oxygen) areas in the world's oceans and large lakes, caused by "excessive nutrient pollution from human activities coupled with other factors that deplete the oxygen required to support most marine life in bottom and near-bottom water".
 * Baltic Sea hypoxia: The total area of bottom covered with hypoxic waters with oxygen concentrations less than 2 mg/l in the Baltic Sea has averaged 49,000 km2 over the last 40 years.
 * Aquatic Dead Zones.jpg


 * Environmental impact of fishing: includes issues such as the availability of fish, overfishing, fisheries, and fisheries management; and issues around the impact of fishing on other elements of the environment, such as by-catch. The journal Science published a four-year study in November 2006, which predicted that, at prevailing trends, the world would run out of wild-caught seafood in 2048. The scientists stated that the decline was a result of overfishing, pollution and other environmental factors that were reducing the population of fisheries at the same time as their ecosystems were being annihilated.
 * Fishing down the food web process whereby fisheries in a given ecosystem, "having depleted the large predatory fish on top of the food web, turn to increasingly smaller species, finally ending up with previously spurned small fish and invertebrates".
 * Environmental issues with salmon: Salmon population levels are of concern in the Atlantic and in some parts of the Pacific. Alaska fishery stocks are still abundant, and catches have been on the rise in recent decades, after the state initiated limitations in 1972.
 * Cod
 * Cod fisheries
 * Collapse of the Atlantic northwest cod fishery: in 1992 the Canadian government declared a moratorium on the Northern Cod fishery, which for the past 500 years had largely shaped the lives and communities of Canada's eastern coast. Tragedy of the commons: Canadian government acted too late. The damage done to Newfoundland's coastal ecosystem proved irreversible. Even after ~20 years, the Northern Cod population has not rebounded and the cod fishery remains closed.
 * Time series for collapse of Atlantic northwest cod.png
 * Marine Stewardship Council: independent non-profit organization which sets a standard for sustainable fishing. Fisheries that wish to demonstrate they are well managed and sustainable compared to the science-based MSC standard are assessed by a team of experts who are independent of both the fishery and the MSC. Seafood products can display the blue MSC ecolabel only if that seafood can be traced back through the supply chain to a fishery that has been certified against the MSC standard.
 * Illegal, unreported and unregulated fishing (IUU): issue around the world. Fishing industry observers believe IUU occurs in most fisheries, and accounts for up to 30% of total catches in some important fisheries.


 * The End of the Line: How Overfishing Is Changing the World and What We Eat (2004): The book provides details about overfishing in many of the world's critical ocean habitats, such as the New England fishing grounds, west African coastlines, the European North Atlantic fishing grounds, and the ocean around Japan.


 * Unsustainable fishing methods: Dynamite fishing, electro-fishing, or fishing with poisons are examples of the latter, used in developing countries. Western unsustainable fishing methods include bottom trawling, which was called a 'great harm' by a group of leading marine environmentalists.
 * Destructive fishing practices: narrowest definition of destructive fishing practices refers principally to bottom trawling over vulnerable habitat (shallow corals, deep sea corals, or seagrass, for example), as well as practices such as shark-finning, blast-fishing, poison-fishing, muroami, and push-netting. Bottom trawling over vulnerable habitat, however, will continue within the Exclusive Fishing Zones of most nations until governments have mapped the location of vulnerable habitats, and taken steps to exclude all bottom trawling activities from these areas.


 * Bottom trawling ("dragging"): scientific community divides bottom trawling into benthic trawling and demersal trawling.

Waste management, recycling, (sustainability)

 * Category:Environmental issues
 * Category:Waste
 * Category:Waste management
 * Category:Recycling
 * Category:Sustainability and environmental management
 * Category:Waste management
 * Category:Sustainability
 * Category:Recycling
 * Category:Environmental economics


 * Recycling symbol (Unicode: ♲ (U+2672) or ♻ (U+267B))
 * Resin identification code: ♳, PETE or PET (Polyethylene terephthalate); ♴, HDPE (High-density polyethylene); ♵, PVC or V (Polyvinyl chloride); ♶, LDPE (Low density polyethylene); ♷, PP (Polypropylene); ♸, PS (Polystyrene); ♹, OTHER or O; ABS (Acrylonitrile butadiene styrene)


 * Circular economy: generic term for an industrial economy that is, by design or intention, restorative and in which material flows are of two types, biological nutrients, designed to reenter the biosphere safely, and technical nutrients, which are designed to circulate at high quality without entering the biosphere.
 * Natural capital
 * Cradle-to-cradle design
 * Permaculture: branch of ecological design, ecological engineering, environmental design, construction and integrated water resources management that develops sustainable architecture, regenerative and self-maintained habitat and agricultural systems modeled from natural ecosystems.
 * Transition town: grassroot community project that seeks to build resilience in response to peak oil, climate destruction, and economic instability.


 * Waste-to-energy: process of generating energy in the form of electricity and/or heat from the primary treatment of waste. WtE is a form of energy recovery. Most WtE processes produce electricity and/or heat directly through combustion.

Sewage

 * Cesspit: pit, conservancy tank or covered cistern which can be used to dispose of urine and feces, and more generally of all sewage and refuse. In 1846: 100 cesspits were cleaned in Paris every night, by 200-250 total cesspit cleaners in the city, and out of a total of 30,000 cesspits.
 * Sewage treatment: sewage (domestic) and runoff (e.g. rain runoff) treatment. Usually rain water and sewage are separated in modernly built cities.


 * Combined sewer: type of gravity sewer with a system of pipes, tunnels, pump stations etc. to transport sewage and urban runoff together to a sewage treatment plant or disposal site. This means that during rain events, the sewage gets diluted, resulting in higher flowrates at the treatment site. Combined sewers can cause serious water pollution problems during combined sewer overflow (CSO) events when combined sewage and surface runoff flows exceed the capacity of the sewage treatment plant, or of the maximum flow rate of the system which transmits the combined sources. In instances where exceptionally high surface runoff occurs (such as large rainstorms), the load on individual tributary branches of the sewer system may cause a back-up to a point where raw sewage flows out of input sources such as toilets, causing inhabited buildings to be flooded with a toxic sewage-runoff mixture, incurring massive financial burdens for cleanup and repair. When combined sewer systems experience these higher than normal throughputs, relief systems cause discharges containing human and industrial waste to flow into rivers, streams, or other bodies of water. Such events frequently cause both negative environmental and lifestyle consequences, including beach closures, contaminated shellfish unsafe for consumption, and contamination of drinking water sources, rendering them temporarily unsafe for drinking and requiring boiling before uses such as bathing or washing dishes.

Nuclear accidents, radioactive contamination

 * Category:Environmental impact of nuclear power
 * Category:Nuclear accidents and incidents
 * Category:Radioactive contamination
 * Category:Military nuclear accidents and incidents
 * Category:Radiation accidents and incidents
 * Category:Radiation health effects
 * Category:Chernobyl disaster

{q.v. } Nuclear:
 * Acute radiation syndrome (radiation poisoning, radiation sickness or radiation toxicity)
 * Corium (nuclear reactor) (fuel containing material, lava-like fuel containing material): lava-like material created in the core of a nuclear reactor during a meltdown accident. Consists of a mixture of nuclear fuel, fission products, control rods, structural materials from the affected parts of the reactor, products of their chemical reaction with air, water and steam, and, in the event that the reactor vessel is breached, molten concrete from the floor of the reactor room.
 * Nuclear fallout
 * International Nuclear Event Scale (1990)
 * Kyshtym disaster: 29 September 1957; level 6.
 * Mayak (Mayak Production Association; Chelyabinsk-40 and later as Chelyabinsk-65): industrial complex which is one of the biggest nuclear facilities in the Russian Federation. It housed plutonium production reactors and a reprocessing plant.
 * Chernobyl disaster (1986.04.25-26; level 7): catastrophic nuclear accident in the No. 4 nuclear reactor at the Chernobyl Nuclear Power Plant, near the city of Pripyat, in northern Ukrainian SSR. Accident occurred during a late-night safety test which simulated a station blackout power-failure, during the course of which both emergency safety and power-regulating systems were intentionally turned off for testing. A combination of inherent reactor design flaws as well as reactor operators arranging the core in a manner contrary to the checklist for the test, resulted in uncontrolled reaction conditions. Superheated water was instantly turned into steam causing a destructive steam explosion. This fire produced considerable updrafts for about nine days. The fire was finally contained on 4 May 1986. The lofted plumes of fission products released into the atmosphere by the fire precipitated onto parts of the USSR and western Europe. The estimated radioactive inventory that was released during this very hot fire phase approximately equaled in magnitude the airborne fission products released in the initial destructive explosion. The Chernobyl accident is considered the most disastrous nuclear power plant accident in history, both in terms of cost and casualties.
 * Chernobyl compared to other radioactivity releases
 * Red Forest
 * Chernobyl Nuclear Power Plant sarcophagus
 * New Safe Confinement
 * Chernobyl after the disaster: wildlife under radioactivity
 * Chernobyl Exclusion Zone: the officially designated exclusion area around the site of the Chernobyl nuclear reactor disaster. The Chernobyl Exclusion Zone borders a separately administered area, the Polesie state radiation and ecological reserve, to the north, in Belarus. Today the Exclusion Zone is one of the most radioactively contaminated areas in the world and draws significant scientific interest for the high levels of radiation exposure in the environment, as well as increasing interest from tourists.
 * Valery Legasov (1936.09.01–1988.04.27): prominent USSR inorganic chemist and a member of the Academy of Sciences of the USSR. He is now mainly remembered for his work as the chief of the commission investigating the Chernobyl disaster. He took the most important decisions to avoid repeat accidents and informed the government of the situation in the disaster area. He did not hesitate to speak to his fellow scientists and to the press about the safety risks of the destroyed plant and insisted on the immediate evacuation of the entire population of the city of Pripyat nearby. In 1986.08, he presented the report of the Soviet delegation at the special meeting of IAEA in Vienna. Legasov's suicide caused shockwaves in the Soviet nuclear industry. In particular, the problem with the design of the control rods in Chernobyl-type RBMK reactors was rapidly admitted and changed.


 * Operation Crossroads (mid-1946; Bikini Atoll): The Baker test's radioactive contamination of all the target ships was the first case of immediate, concentrated radioactive fallout from a nuclear explosion. Chemist Glenn T. Seaborg, the longest-serving chairman of the Atomic Energy Commission, called Baker "the world's first nuclear disaster."
 * Soviet submarine K-19: 1961.07.04 submarine suffered a complete loss of coolant to its reactor. With no backup system, the captain ordered members of the engineering crew to find a solution to avoid a nuclear meltdown. Sacrificing their own lives, 22 crew members jury-rigged a secondary coolant system and kept the reactor from exploding.


 * Linear no-threshold model: used in radiation protection to quantify radiation exposition and set regulatory limits. It assumes that the long term, biological damage caused by ionizing radiation (essentially the cancer risk) is directly proportional to the dose. This allows the summation by dosimeters of all radiation exposure, without taking into consideration dose levels or dose rates. UNSCEAR: "the Scientific Committee does not recommend multiplying very low doses by large numbers of individuals to estimate numbers of radiation-induced health effects within a population exposed to incremental doses at levels equivalent to or lower than natural background levels;" this is a reversal from previous recommendations by the same organization.

Nuclear war:
 * Hiroshima (book)

Water, sanitation, sewerage, hygiene

 * Category:Water supply
 * Category:Drinking water
 * Category:Water filters
 * Category:Water pollution
 * Category:Hygiene
 * Category:Sanitation
 * Category:Sewerage

{q.v. User:Kazkaskazkasako/Work}


 * Water pollution (aquatic pollution): contamination of water bodies, usually as a result of human activities, in such a manner that negatively affects its legitimate uses. Water pollution reduces the ability of the body of water to provide the ecosystem services that it would otherwise provide. All plants and organisms living in or being exposed to polluted water bodies can be impacted. The effects can damage individual species and impact the natural biological communities they are part of. Water pollution can also lead to water-borne diseases for people using polluted water for drinking, bathing, washing or irrigation. Approx 785 mln people in the world do not have access to clean drinking water because of pollution. Pollution may take the form of toxic substances (e.g., oil, metals, plastics, pesticides, persistent organic pollutants, industrial waste products), stressful conditions (e.g., changes of pH, hypoxia or anoxia, stressful temperatures, excessive turbidity, unpleasant taste or odor, and changes of salinity), or pathogenic organisms. Contaminants may include organic and inorganic substances. Heat can also be a pollutant, and this is called thermal pollution. A common cause of thermal pollution is the use of water as a coolant by power plants and industrial manufacturers. Types of surface water pollution. Groundwater pollution.


 * Sanitation: hygienic means of promoting health through prevention of human contact with the hazards (physical, microbiological, biological or chemical agents of disease) of wastes (human and animal feces, solid wastes, domestic wastewater (sewage, sullage, greywater), industrial wastes and agricultural wastes) as well as the treatment and proper disposal of sewage wastewater.
 * World Toilet Organization (WTO; :D NOT the World Trade Org; 2001-): global non-profit organization committed to improving toilet and sanitation conditions worldwide; working towards eliminating the toilet taboo and delivering sustainable sanitation.
 * Sustainable Sanitation Alliance (SuSanA): network formed by organisations active in the field of sustainable sanitation


 * Water supply and sanitation in Sub-Saharan Africa: Sub-Saharan Africa is unlikely to meet the Millennium Development Goals of halving the share of the population without access to safe drinking water and sanitation between 1990 and 2015. There are, however, large disparities among Sub-Saharan countries, and between the urban and rural areas. Usually, water is provided by utilities in urban areas and municipalities or community groups in rural areas. Sewerage is not common and wastewater treatment even less. Sanitation is often in the form of individual or communal latrines. The best performer in the region is South Africa (S.A. introduced free basic utility services for all, including 6m3 of water per month for free).
 * 2018–20 Southern Africa drought: ongoing period of drought taking place in Southern Africa. The drought began in late October 2018, and is negatively affecting food security in the region. As of mid-August 2019, the drought is classified as a level 2 Red-Class event by the Global Disaster Alert and Coordination System.
 * Cape Town water crisis: period of severe water shortage in the Western Cape region, most notably affecting the City of Cape Town. While dam water levels had been declining since 2015, the Cape Town water crisis peaked during mid-2017 to mid-2018 when water levels hovered between 15% and 30% of total dam capacity. "Day Zero" would herald the start of Level 7 water restrictions, when municipal water supplies would largely be switched off and residents would have to queue for their daily ration of water, making the City of Cape Town the first major city in the world to potentially run out of water. Causes: Severe drought, Long-term demand and supply management, Government failure.


 * Water politics in the Middle East: Water issues reflect a central aspect of the nature of the Israeli–Palestinian conflict; namely, the original influx of an additional large population mass to a relatively fragile geographical area of land, and the massive expansion of previously existing populations.
 * Water politics in the Jordan River basin: Arab-Israeli conflict and water


 * Water supply and sanitation in India

Water filters:
 * Slingshot (water vapor distillation system): water purification device created by inventor Dean Kamen. Powered by a Stirling engine running on a combustible fuel source, it claims to be able to produce drinking water from almost any source by means of vapor compression distillation, requires no filters, and can operate using cow dung as fuel.
 * LifeSaver bottle: portable water purification device. The bottle filters out objects larger than 15 nm. After the 2004 Asian tsunami and Hurricane Katrina disaster in the U.S., Michael Pritchard, a water-treatment expert in Ipswich, England began to develop the LifeSaver bottle after seeing that it took multiple days for water to reach refugees. Speaking at TED in 2009, Pritchard estimated that by using the LifeSaver bottle, reaching the Millennium Development Goals of halving the number of people without drinking water will cost $8 bln; while $20 bln would provide drinking water for everyone on Earth.
 * LifeStraw: brand that manufactures water filtration and purification devices. The first product (the original LifeStraw) was designed as a portable water filter "straw". It filters a maximum of 4000 litres of water, enough for one person for three years. It removes almost all of waterborne bacteria, microplastics and parasites.
 * Tata Swach: water purifier developed by Tata Chemicals; designed as a low cost purifier for Indian low-income groups, who lack access to safe drinking water.
 * Sono arsenic filter: invented in 2006 by Abul Hussam, who is a chemistry professor at George Mason University. It was developed to deal with the problem of arsenic contamination of groundwater. The filter is now in use in Hussam's native Bangladesh.

Physical and chemical properties of water

 * Category:Water
 * Category:Water chemistry
 * Category:Water physics


 * Self-ionization of water: autoionization of water, and autodissociation of water) is an ionization reaction in pure water or in an aqueous solution, in which a water molecule, H₂O, deprotonates (loses the nucleus of one of its hydrogen atoms) to become a hydroxide ion, OH⁻. The hydrogen nucleus, H⁺, immediately protonates another water molecule to form hydronium, H3O⁺. It is an example of autoprotolysis, and exemplifies the amphoteric nature of water. Ionization constant, dissociation constant, self-ionization constant, water ion-product constant or ionic product of water $$K_{\rm w}=[{\rm{H_3O^+}}][{\rm{OH^-}}]$$. At 25°C and zero ionic strength, Kw is equal to $695,508$.


 * Electromagnetic absorption by water: The absorption in the gas phase occurs in three regions of the spectrum. Rotational transitions are responsible for absorption in the microwave and far-infrared, vibrational transitions in the mid-infrared and near-infrared. Vibrational bands have rotational fine structure. Electronic transitions occur in the vacuum ultraviolet regions. Liquid water has no rotational spectrum but does absorb in the microwave region. Its weak absorption in the visible spectrum results in the pale blue color of water. The absorption was attributed to a sequence of overtone and combination bands whose intensity decreases at each step, giving rise to an absolute minimum at 418 nm, at which wavelength the attenuation coefficient is about 0.0044 m⁻¹, which is an attenuation length of about 227 meters.


 * Heavy water (²H₂O, D₂O, deuterium oxide): The presence of the heavier hydrogen isotope gives the water different nuclear properties, and the increase of mass gives it slightly different physical and chemical properties when compared to normal water.
 * Physical properties: One study has concluded that heavy water tastes "distinctly sweeter" for humans, and is mediated by the TAS1R2/TAS1R3 taste receptor. Rats given a choice between distilled normal water and heavy water were able to avoid the heavy water based on smell, and it may have a different taste.
 * Effect on biological systems: To perform their tasks, enzymes rely on their finely-tuned networks of hydrogen bonds, both in the active center with their substrates, and outside the active center, to stabilize their tertiary structures. As a hydrogen bond with deuterium is slightly stronger than one involving ordinary hydrogen, in a highly deuterated environment, some normal reactions in cells are disrupted. Particularly hard-hit by heavy water are the delicate assemblies of mitotic spindle formations necessary for cell division in eukaryotes. Plants stop growing and seeds do not germinate when given only heavy water, because heavy water stops eukaryotic cell division. Experiments showed that bacteria can live in 98% heavy water. However, all concentrations over 50% of deuterium in the water molecules were found to kill plants. Effect on animals; Toxicity in humans; Heavy water radiation contamination confusion.
 * Production: USSR, USA, India, Norway (WWII), Canada: CANDU (AECL is currently researching other more efficient and environmentally benign processes for creating heavy water. Heavy water represents about 15–20% of the total capital cost of each CANDU plant), Iran, Pakistan
 * Applications: NMR, Organic chemistry, Infrared spectroscopy (FTIR), Neutron moderator, Neutrino detector, Metabolic rate testing in physiology and biology (Doubly labeled water test), Tritium production.


 * Ultrapure water (UPW, high-purity water or highly purified water (HPW)): water that has been purified to uncommonly stringent specifications. Ultrapure water is a term commonly used in manufacturing to emphasize the fact that the water is treated to the highest levels of purity for all contaminant types, including: organic and inorganic compounds; dissolved and particulate matter; volatile and non-volatile; reactive, and inert; hydrophilic and hydrophobic; and dissolved gases. UPW and commonly used term deionized (DI) water are not the same. In addition to the fact that UPW has organic particles and dissolved gases removed, a typical UPW system has three stages: a pretreatment stage to produce purified water, a primary stage to further purify the water, and a polishing stage, the most expensive part of the treatment process. A number of organizations and groups develop and publish standards associated with the production of UPW. For microelectronics and power, they include Semiconductor Equipment and Materials International (SEMI) (microelectronics and photovoltaic), American Society for Testing and Materials International (ASTM International) (semiconductor, power), Electric Power Research Institute (EPRI) (power), American Society of Mechanical Engineers (ASME) (power), and International Association for the Properties of Water and Steam (IAPWS) (power). Pharmaceutical plants follow water quality standards as developed by pharmacopeias, of which three examples are the United States Pharmacopeia, European Pharmacopeia, and Japanese Pharmacopeia.
 * Analytical methods and techniques:
 * On-line analytical measurements:
 * Conductivity/resistivity: Absolutely pure water has a conductivity of 0.05501 μS/cm and a resistivity of 18.18 Mohm•cm at 25 °C, the most common reference temperature to which these measurements are compensated. An example of the sensitivity to contamination of these measurements is that 0.1 ppb of NaCl raises the conductivity of pure water to 0.05523 μS/cm and lowers the resistivity to 18.11 Mohm•cm. Ultrapure water is easily contaminated by traces of carbon dioxide from the atmosphere passing through tiny leaks or diffusing through thin wall polymer tubing when sample lines are used for measurement. Carbon dioxide forms conductive carbonic acid in water. For this reason, conductivity probes are most often permanently inserted directly into the main ultrapure water system piping to provide real-time continuous monitoring of contamination. These probes contain both conductivity and temperature sensors to enable accurate compensation for the very large temperature influence on the conductivity of pure waters. Conductivity probes have an operating life of many years in pure water systems. They require no maintenance except for periodic verification of measurement accuracy, typically annually.
 * Sodium
 * Dissolved oxygen (DO)
 * Silica
 * Particles
 * Non-volatile residue
 * Total organic carbon (TOC)

Food

 * Category:Food and drink
 * Category:Food and the environment
 * Category:Sustainable food system
 * Category:Food politics
 * Category:Food security

{q.v. }


 * Template:Consumer food safety
 * Adulterants, food contaminants
 * Flavorings
 * Intestinal parasites and parasitic disease
 * Microorganisms
 * Pesticides
 * Preservatives
 * Sugar substitutes
 * Toxins, poisons, environment pollution
 * Food contamination incidents
 * Regulation, standards, watchdogs
 * Food processing
 * Institutions


 * Food security: condition related to the ongoing availability of food. Concerns over food security have existed throughout history. There is evidence of granaries being in use over 10,000 years ago, with central authorities in civilizations including Ancient China and Ancient Egypt being known to release food from storage in times of famine. FAO: food security "exists when all people, at all times, have physical and economic access to sufficient, safe and nutritious food to meet their dietary needs and food preferences for an active and healthy life".
 * 2022–2023 food crises: year 2022 saw a rapid increase in food prices and shortages of food supplies around the world. The worsening crises in distinct parts of the world were caused by compounding geopolitical and economic crisis. The crises followed food security and economic crises during the COVID-19 pandemic. The world food prices went down again by 18% in 2023.01 since 2022.03. Nevertheless, FAO warns of the double-digit food inflation that are still happening in dozens of countries. The compounding issues, including the Russian invasion of Ukraine, as well as climate-related crop failures, are feared to reverse global trends in reducing hunger and malnutrition.


 * Cultured meat (cell-cultured meat, in vitro meat): meat grown inside cell culture instead of animals. In the 21st century, several research projects have worked on cultured meat in the laboratory. The first cultured beefburger, created by a Dutch team, was eaten at a demonstration for the press in London in 2013.08. There remain difficulties to be overcome before cultured meat becomes commercially available. Cultured meat is prohibitively expensive, but it is expected that the cost could be reduced to compete with that of conventionally obtained meat as technology improves.


 * Arsenic contamination of groundwater: form of groundwater pollution which is often due to naturally occurring high concentrations of arsenic in deeper levels of groundwater. A 2007 study found that over 137 million people in more than 70 countries are probably affected by arsenic poisoning of drinking water. The problem became serious health concern after mass poisoning of water in Bangladesh. Arsenic contamination of ground water is found in many countries throughout the world, including the USA.

Environmental science

 * Category:Environmental science
 * Category:Environmental chemistry
 * Category:Systems ecology
 * Category:Ecosystems
 * Category:Aquatic ecology
 * Category:Toxicology
 * Category:Water pollution
 * Category:Biogeochemistry
 * Category:Ecology
 * Category:Environmental non-fiction books


 * List of years in the environment: subjects relate to environmental law, conservation, environmentalism and environmental issues.


 * Biogeochemistry: study of the chemical, physical, geological, and biological processes and reactions that govern the composition of the natural environment (including the biosphere, the cryosphere, the hydrosphere, the pedosphere, the atmosphere, and the lithosphere). In particular, biogeochemistry is the study of the cycles of chemical elements, such as carbon and nitrogen, and their interactions with and incorporation into living things transported through earth scale biological systems in space and time. The field focuses on chemical cycles which are either driven by or influence biological activity. Particular emphasis is placed on the study of carbon, nitrogen, sulfur, iron, and phosphorus cycles. Biogeochemistry is a systems science closely related to systems ecology. [Is plastic part of carbon cycle?]


 * Ecosystem (ecological system): consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the system through photosynthesis and is incorporated into plant tissue. By feeding on plants and on one another, animals play an important role in the movement of matter and energy through the system. They also influence the quantity of plant and microbial biomass present. By breaking down dead organic matter, decomposers release carbon back to the atmosphere and facilitate nutrient cycling by converting nutrients stored in dead biomass back to a form that can be readily used by plants and other microbes.


 * Mesocosm (meso- or 'medium' and -cosm 'world'): any outdoor experimental system that examines the natural environment under controlled conditions. In this way mesocosm studies provide a link between field surveys and highly controlled laboratory experiments. Mesocosms also tend to be medium-sized to large (e.g., aquatic mesocosm range: 1 to > 10,000 L) and contain multiple trophic levels of interacting organisms.


 * Abyssal zone (abyssopelagic zone): layer of the pelagic zone of the ocean. "Abyss" derives from the Greek word ἄβυσσος, meaning bottomless. At depths of 3,000 to 6,000 metres, this zone remains in perpetual darkness. It covers 83% of the total area of the ocean and 60% of the Earth's surface. The abyssal zone has temperatures around 2 to 3 °C through the large majority of its mass. Due to there being no light, there are no plants producing oxygen, which primarily comes from ice that had melted long ago from the polar regions. The water along the seafloor of this zone is actually devoid of oxygen, resulting in a death trap for organisms unable to quickly return to the oxygen-enriched water above. This region also contains a much higher concentration of nutrient salts, like nitrogen, phosphorus, and silica, due to the large amount of dead organic material that drifts down from the above ocean zones and decomposes. The water pressure can reach up to 76 MPa (750 atm). Environmental concerns: As with all of the rest of the natural world climate change has negative effects. Due to the zone’s depth, increasing global temperatures do not affect it as quickly or drastically as the rest of the world, but the zone is still afflicted by ocean acidification. Along with climate change and ocean acidification, pollutants, such as plastics, are also present in this zone. Plastics are especially bad for the abyssal zone due to the fact that these organisms have evolved to eat or try to eat anything that moves or appears to be detritus, resulting in most organisms consuming plastics instead of nutrients. Both ocean acidification and pollution are decreasing the already small biomass that resides within the abyssal zone. Another problem caused by humans is overfishing.


 * Silent Spring: environmental science book by Rachel Carson. The book was published in 1962.09.27, documenting the adverse environmental effects caused by the indiscriminate use of pesticides. Carson accused the chemical industry of spreading disinformation, and public officials of accepting the industry's marketing claims unquestioningly. It spurred a reversal in the United States' national pesticide policy, led to a nationwide ban on DDT for agricultural uses, and helped to inspire an environmental movement that led to the creation of the USA EPA.


 * Nekton (νήκτον, translit. nekton, lit. "to swim"): actively swimming aquatic organisms in a body of water. The term was proposed by German biologist Ernst Haeckel to differentiate between the active swimmers in a body of water, and the passive organisms that were carried along by the current, the plankton. As a guideline, nektonic organisms have a high Reynolds number (greater than 1000) and planktonic organisms a low one (less than 10). However, some organisms can begin life as plankton and transition to nekton later on in life, sometimes making distinction difficult when attempting to classify certain plankton-to-nekton species as one or the other. For this reason, some biologists choose not to use this term.


 * Dissolved organic carbon (DOC): fraction of organic carbon operationally defined as that which can pass through a filter with a pore size typically between 0.22 and 0.7 micrometers. The fraction remaining on the filter is called particulate organic carbon (POC). Dissolved organic matter (DOM) is a closely related term often used interchangeably with DOC. While DOC refers specifically to the mass of carbon in the dissolved organic material, DOM refers to the total mass of the dissolved organic matter. So DOM also includes the mass of other elements present in the organic material, such as nitrogen, oxygen and hydrogen. DOC is a component of DOM and there is typically about twice as much DOM as DOC. Many statements that can be made about DOC apply equally to DOM, and vice versa.

Ecology

 * Category:Ecology @Template:Category diffuse, Contrast|Environmental issues
 * Category:Biogeography
 * Category:Ecology terminology


 * Ecology (οἶκος, "house" and -λογία, "study of"): study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organisms at the individual, population, community, ecosystems, and biosphere level. Ecology overlaps with the closely related sciences of biogeography, evolutionary biology, genetics, ethology and natural history. Ecology is a branch of biology, and it is not synonymous with environmentalism. Evolutionary concepts relating to adaptation and natural selection are cornerstones of modern ecological theory. Ecosystems are dynamically interacting systems of organisms, the communities they make up, and the non-living components of their environment. Ecosystem processes, such as primary production, nutrient cycling, and niche construction, regulate the flux of energy and matter through an environment. Ecosystems have biophysical feedback mechanisms that moderate processes acting on living (biotic) and non-living (abiotic) components of the planet. Ecosystems sustain life-supporting functions and provide ecosystem services like biomass production (food, fuel, fiber, and medicine), the regulation of climate, global biogeochemical cycles, water filtration, soil formation, erosion control, flood protection, and many other natural features of scientific, historical, economic, or intrinsic value. Levels, scope, and scale of organization: Hierarchy; Biodiversity; Habitat; Ecological niche; Niche construction; Biome {q.v. }; Biosphere; Population ecology; Metapopulations and (animal) migration; Community ecology; Ecosystem ecology; Food webs; Trophic levels; Keystone species. Complexity (Emergence): Holism. Relation to evolution: Behavioural ecology, Cognitive ecology, Social ecology, Coevolution, Biogeography {q.v. }: r/K selection theory, Molecular ecology. Human ecology: Restoration and management (Natural resource management). Relation to the environment: Disturbance and resilience; Metabolism and the early atmosphere; Radiation: heat, temperature and light; Physical environments: Water, Gravity, Pressure, Wind and turbulence, Fire, Soil ecology, Biogeochemistry and climate.
 * Theoretical ecology


 * Buffer strip: area of land maintained in permanent vegetation that helps to control air, soil, and water quality, along with other environmental problems, dealing primarily on land that is used in agriculture. Buffer strips trap sediment, and enhance filtration of nutrients and pesticides by slowing down runoff that could enter the local surface waters.
 * Riparian buffer: vegetated area near a stream, usually forested, which helps shade and partially protect a stream from the impact of adjacent land uses. It plays a key role in increasing water quality in associated streams, rivers, and lakes, thus providing environmental benefits.
 * Windbreak


 * Cosmopolitan distribution: if its range extends across all or most of the world in appropriate habitats.

Toxins, poisons

 * Category:Toxicology
 * Category:Poisons
 * Category:Toxins
 * Category:Toxicants

{q.v. }


 * Template:Toxins
 * Bacterial toxins
 * Mycotoxins
 * Plant toxins
 * Invertebrate toxins
 * Vertebrate toxins


 * Aflatoxin: poisonous carcinogens and mutagens that are produced by certain molds (Aspergillus flavus and Aspergillus parasiticus) which grow in soil, decaying vegetation, hay, and grains. They are regularly found in improperly stored staple commodities such as cassava, chili peppers, cottonseed, millet, peanuts, rice, sesame seeds, sorghum, sunflower seeds, sweetcorn, tree nuts, wheat, and a variety of spices. When contaminated food is processed, aflatoxins enter the general food supply where they have been found in both pet and human foods, as well as in feedstocks for agricultural animals. Animals fed contaminated food can pass aflatoxin transformation products into eggs, milk products, and meat.
 * Aflatoxin B1: very potent carcinogen with a TD50 3.2 μg/kg/day in rats. This carcinogenic potency varies across species with some, such as rats and monkeys, seemingly much more susceptible than others.
 * Aflatoxin M1: chemical compound of the aflatoxin class, a group of mycotoxins produced by three species of Aspergillus - Aspergillus flavus, Aspergillus parasiticus, and the rare Aspergillus nomius - which contaminate plant and plant products. Aflatoxin M1 is the hydroxylated metabolite of aflatoxin B1 and can be found in milk or milk products obtained from livestock that have ingested contaminated feed. The carcinogenic potency of aflatoxin M1 in sensitive species is about one order of magnitude less than that of aflatoxin B1. Aflatoxin M1 is usually considered to be a detoxication by-product of aflatoxin B1.

Oceanography

 * Category:Oceanography
 * Category:Chemical oceanography


 * Brine rejection: process that occurs during sea ice formation where salt is pushed from forming ice into the surrounding seawater, creating saltier, denser brine.
 * Thermohaline circulation
 * Atlantic meridional overturning circulation (AMOC): zonally integrated component of surface and deep currents in the Atlantic Ocean. It is characterized by a northward flow of warm, salty water in the upper layers of the Atlantic, and a southward flow of colder, deep waters that are part of the thermohaline circulation. These "limbs" are linked by regions of overturning in the Nordic and Labrador Seas and the Southern Ocean, although the extent of overturning in the Labrador Sea is disputed. The AMOC is an important component of the Earth's climate system, and is a result of both atmospheric and thermohaline drivers. Model projections suggest that the strength of the AMOC is “very likely” to decrease over the course of the 21st century due to climate change, which is likely to have an impact on weather patterns and sea level. Paleoclimate reconstructions and some models also raise the possibility of an AMOC collapse, which would likely affect the weather and climate system. This makes the AMOC an important climate indicator to monitor.


 * Early Holocene sea level rise (EHSLR): significant jump in sea level by about 60 m (197 ft) during the early Holocene, between about 12,000 and 7,000 years ago, spanning the Eurasian Mesolithic. The rapid rise in sea level and associated climate change, notably the 8.2 ka cooling event (8,200 years ago), and the loss of coastal land favoured by early farmers, may have contributed to the spread of the Neolithic Revolution to Europe in its Neolithic period.
 * Meltwater pulse 1A: by Quaternary geologists, paleoclimatologists, and oceanographers for a period of rapid post-glacial sea level rise, between 13,500 and 14,700 calendar years ago, during which global sea level rose between 16 meters and 25 meters in about 400–500 years, giving mean rates of roughly 40–60 mm/yr.
 * Meltwater pulse 1B: name used by Quaternary geologists, paleoclimatologists, and oceanographers for a period of either rapid or just accelerated post-glacial sea level rise that some hypothesize to have occurred between 11,500 and 11,200 calendar years ago at the beginning of the Holocene and after the end of the Younger Dryas. Meltwater pulse 1B is also known as catastrophic rise event 2 (CRE2) in the Caribbean Sea.
 * Sea level rise: increase in global mean sea level as a result of an increase in the volume of water in the world’s oceans. Sea level rise is usually attributed to global climate change by thermal expansion of the water in the oceans and by melting of ice sheets and glaciers on land. Sea level rise is expected to continue for centuries. Because of long response times for parts of the climate system, it has been estimated that we are already committed to a sea-level rise within the next 2,000 years of approximately 2.3 m for each degree Celsius of temperature rise. 2017.01 NOAA report suggests a range of GMSL rise of 0.3 – 2.5 m possible during the 21st century.
 * Past sea level: global or eustatic sea level has fluctuated significantly over Earth's history. The main factors affecting sea level are the amount and volume of available water and the shape and volume of the ocean basins. The primary influences on water volume are the temperature of the seawater, which affects density, and the amounts of water retained in other reservoirs like rivers, aquifers, lakes, glaciers, polar ice caps and sea ice. Over geological timescales, changes in the shape of the oceanic basins and in land/sea distribution affect sea level. In addition to eustatic changes, local changes in sea level are caused by tectonic uplift and subsidence.


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