Wikipedia:Reference desk/Archives/Science/2008 November 15

= November 15 =

Vapor pressure
If I understand the subject at hand correctly (which, not having taken a chemistry course, I probably don't), all substances, including solids, have a vapor pressure, and if atmospheric pressure is reduced to below this vapor pressure, the substance at hand will evaporate/sublimate away. If so, why can solid objects exist in space (a complete vacuum)? Shouldn't they have sublimated away long since? 69.177.191.60 (talk) 00:54, 15 November 2008 (UTC)
 * From Vapor pressure, "due to their often extremely low values, measurement can be rather difficult". Outer space isn't actually a complete vacuum. Objects that are sent into space (spacecraft, satellites, etc.) are designed to have even lower vapor pressures than everyday objects.  Axl  ¤  [Talk]  01:04, 15 November 2008 (UTC)

Does gravity hold things in space together? Even small objects have gravity, which may be great enough to prevent the escape of atoms on their surface. It is theorized that the atmosphere of the earth's moon, and other rather small objects in space, has gradually escaped the gravitational pull. But atoms of a solid material may be unable to escape the gravitional pull of the parent body. —Preceding unsigned comment added by 98.17.34.3 (talk) 14:28, 15 November 2008 (UTC)


 * In order to change state from solid to gas, energy is required, see phase transition. There is very little heat in the 'vacuum' of space and no energy to cause the sublimation.  Everyday objects also not not sublime when in a vacuum chamber for example.  Most everyday objects are pretty stable, it is only when objects are heated close to their melting / boiling temperature that the most energetic particles close to the surface of the material will begin to vapourise. Of course a vacuum will lower these temperatures but if you do not supply energy to a system it cannot gain the energy suuficient for vapourisation. Jdrewitt (talk) 14:50, 15 November 2008 (UTC)


 * I remember somebody on this reference desk mentioning that solids do sublime in space, just so slowly as to be unnoticeable. — DanielLC 23:37, 15 November 2008 (UTC)


 * That might be true but once the most energetic particles have escaped there is no extra energy into the system to provide additional particles with the required energy to escape. It's the same principle I guess as why a puddle of water evaporates on an overcast day.  Some of the particles of water in the puddle have enough energy to escape and vapourise.  This is a Boltzmann distribution.  The surroundings provide the puddle with enough energy to maintain the distribution and so there are always some particles with enough energy to escape from the liquid phase.  Going back to the solid in space there might be, at the beginning, some particles with enough energy to sublime but there is no (or very little) energy to top up the system so none of the particles will have the energy required to sublime. Jdrewitt (talk) 10:07, 16 November 2008 (UTC)

Frameshift mutation.
Would a frame shift mutation affect the building of only one protein, or does the frame shift extend beyond the first stop codon? Can the entire chromosome be read as codons in groups of three, or can the codons start at positions offset from a multiple of three from the very first nucleotide at the 5' end? Basically I'm sure that if a point mutation occurs, it presumably it doesn't affect the entire chromosome, but I'm not sure how. Jooler (talk) 01:06, 15 November 2008 (UTC)


 * Think about what nucleic acid is used by the ribosome to generate protein. How is that nucleic acid formed?  Is it a complete chromosome copy, or some smaller unit?  --Scray (talk) 05:05, 15 November 2008 (UTC)


 * Jooler, did you figure out the answer to your question yet? If not, I would like to explain it, but I would rather not write all the extra stuff if you don't need it now... 152.16.15.23 (talk) 16:57, 17 November 2008 (UTC)


 * Yes. please explain! Thanks. Jooler (talk) 00:33, 18 November 2008 (UTC)

General equation for two bases (or metal hydroxides) reacting
Hi guys, just doing some basic chemistry and the general equation (i.e. Acid + Base -> Water + Salt) for when two bases (or metal hydroxides) react has eluded me. Specifically, I am looking for the gener equation that would help me determine the below reaction:

$$KOH + Fe(OH)_3 \rightarrow$$

Thanks. Foxy Loxy Pounce! 02:01, 15 November 2008 (UTC)al
 * Hydroxide, beside being a Bronsted base is also a good Lewis base and thus often forms complex ions with transition metals. My best guess is some form of iron(III)hydroxyl ion:
 * Fe(OH)x(3-x)
 * it probably depends on the coordination number of Iron(III) as to the specific formula, but my guess is that this forms a complex ion of some sort. See, especially the description of Reactions of iron ions in solution and the following section Reactions of the iron ions with hydroxide ions.  Good luck!  --Jayron32. talk . contribs  02:20, 15 November 2008 (UTC)
 * Actually, I am probably wrong there. It looks like no reaction will occur in this case, the article I cite makes the claim that iron does not form soluble hydroxide complexes, and this page:  also states: "Another reaction type frequent seen is the formation of a hydroxide followed by the formation of a soluble hydroxide complex ion. Fe(OH)3 and Mg(OH)2 do not form soluble complexes, but aluminum and zinc do".  Looks like no reaction will occur given those reactants!  --Jayron32. talk . contribs  02:30, 15 November 2008 (UTC)
 * Well that explains why I could not think of the equation! Thank you very much. Foxy Loxy  Pounce! 03:40, 15 November 2008 (UTC)

Fuller's formuls
This is a civil engineering question.Do anybody help by providing the proof of the Fuller's formula that is used in getting densest mix out of various fractions of construction aggregates?The formula is as follows: p=(d/D)^n where p-fraction of the material passing a certain seive of size d      d-maximum size of the aggregate n-gradation coefficient usually equals 0.45 or 0.5 202.70.74.136 (talk) 02:12, 15 November 2008 (UTC)


 * Well, you obviously want a function that gives p=0 when d=0 and p=1 when d=D. And scale invariance suggests a power law. So that just leaves the question of the correct exponent n. I think the value of 0.45 or 0.5 is reached empirically - this text book says Fuller's original value of 0.5 was "based on wide scale experiments"; this source says "Why 0.45 exponent in Aggregates Gradiation ? The typical answer is: "that's the way we've always done it"". Gandalf61 (talk) 11:14, 15 November 2008 (UTC)

Could u provide me the text of the article by Fuler and Thompson of 1907 about this? —Preceding unsigned comment added by 202.70.74.184 (talk) 14:41, 17 November 2008 (UTC)

Would an organism that could successfully repair all cellular damage be theoretically immortal?
The general consensus seems to be yes, and many think it even attainable. I’m open to be convinced and would like healthy immortality as much as anyone. But my objection is that there is more to an organism than its component cells. Aren’t there general effects which work on the ENTIRE system? For example, over many decades, gravity bends the spine, and causes breasts to sag, and so on. Could it be that these effects work on levels ABOVE the cellular one, on the body as a machine?

If you had a wooden bridge that gradually bowed under the weight of traffic, would you make that bridge healthy just by replacing it splinter by splinter? Aren’t there cracks BETWEEN the splinters, even between molecules, that mean that the replacement of an organism’s cells, one at a time, will not entirely negate the effects of aging? Myles325a (talk) 06:44, 15 November 2008 (UTC)


 * Hmm, this is suspiciously like a homework question. However I'll assume good faith and give you a couple of pointers. See biological immortality. Partly it depends on how you define "immortality". The "goal" of all organisms is to reproduce. Most unicellular organisms undergo asexual reproduction, provided they live long enough with favourable circumstances. The "daughter" organisms have identical DNA to the parent. Perhaps this is a form of immortality? Or has the organism foregone immortality in favour of reproduction? With multicellular organisms (including humans), the intervening connecting tissue between cells needs to be maintained as well as the cells themselves. However in many complex organisms, cells often undergo apoptosis. Axl  ¤  [Talk]  07:25, 15 November 2008 (UTC)


 * Would it be the same organism? Julia Rossi (talk) 08:31, 15 November 2008 (UTC)
 * Aha! The good old Ship of Theseus paradox. SteveBaker (talk) 15:06, 15 November 2008 (UTC)

""We both step and do not step in the same rivers. We are and are not.""

- Heraclitus

Axl ¤  [Talk]  10:08, 15 November 2008 (UTC)


 * You are defining a situation where the hardware of the body is somehow kept in perfect repair. That doesn't cover the "software"...our brains.   I don't think it's clear whether or not our brains could continue to function indefinitely - even though the hardware is OK - would the software keep running.  To pick an example - a Windows PC will gradually run more and more slowly over years of use if you don't periodically "defragment" the hard drive.  Perhaps our minds have similar problems - but maybe there is no built-in "defrag" because we have not evolved to live long enough for it to matter.  We know it'll run for 100 years or more - and it seems that the changes in mental acuity that come with age are related to structural matters that your magic cell repair gizmo would prevent.  So I don't think we know whether the mind (as opposed to the brain) would continue to work indefinitely. SteveBaker (talk) 15:06, 15 November 2008 (UTC)


 * Maybe God was smart enough to install Linux (ext3) instead of Windows (ntfs) and avoid the disk defrag problem. Heehee. Oh no - me brain is open source! -- k a i n a w &trade; 16:26, 15 November 2008 (UTC)
 * Maybe...I'm pretty sure I got given Sinclair BASIC! SteveBaker (talk) 18:11, 15 November 2008 (UTC)


 * I thought of a better analogy for those who don't understand PC's (or who use a sensible operating system and have never defragged anything in their lives!). Imagine a large library.  When they built the library, they filled it full of books and put them all in Dewey-decimal ordering with books in alphabetical order within each group.   The library contains a million books - but only a couple of librarians - who are meticulous about fixing broken bindings and stopping people from dog-earing the books - they clean and polish the shelves and keep the book-worms at bay.  But they never re-organize the shelves.   When the library is new - you can find books really easily - you go to the right category - then you zip along the shelves to the right place in the alphabet - and there is your book.  But over the years, visitors to the library pull out books and sometimes they put them back onto the shelves in the wrong order.  After decades, centuries or millennia, the library gets further and further from its original state of order.   The books, the shelves and the card indices are all kept in perfect repair - but things get harder and harder to find.  Eventually, there are a million books in random order on the shelves and the library stops working - nobody goes there anymore and it "dies".  This kind of "software" disorder could conceivably affect our minds and kill us - even if the 'hardware' of our bodies were immortal. SteveBaker (talk) 18:11, 15 November 2008 (UTC)


 * This might be unrelated to reparing cellular damage, but there is an organism that will revert back to its polyp stage as it ages, rendering it effectively immortal: turritopsis nutricula. ~ A H  1 (TCU) 21:32, 15 November 2008 (UTC)


 * Indeed - and amoeba reproduce by splitting in two - at no point does an amoeba die of old age. Every amoeba that exists or ever has existed is (in essence) a piece of one single original immortal amoeba.  That hurts my brain! SteveBaker (talk) 01:05, 16 November 2008 (UTC)

Tissue engineering could completely replace the organs and other body parts of a human as they wore out, but the brain would have to be very slowly replaced allowing the mind time to settle in to replaced areas to maintain personal identity, particularly the frontal lobes. As for defragmentation, in humans this process is called sleep.Trevor Loughlin (talk) 08:31, 16 November 2008 (UTC)


 * Yes - I've long believed that dreams are the consequences of the brain having to keep running while it's "defragged" (memories undergoing large scale reorganization) - because severe processing errors can happen during this process - it's necessary to "disconnect" the brain from the limbs and from 'consciousness' to avoid major practical problems. False memories formed during the reorganization are also supressed - which is why we generally forget our dreams so quickly.


 * However, my "defragging" analogy was not intended as a definite "reason" why we might fail to survive forever - merely an example of the kind of software process that could cause an eventual "crash" that might kill us even when the body is working just fine. It's also possible that there is no such process and that dreaming fixes the 'defragging' kinds of issues and we truly could become immortal if we had perfect cellular repair mechanisms.  We don't know for sure either way.


 * SteveBaker (talk) 15:35, 16 November 2008 (UTC)

publishing thesis
how i can publish my pHD thesis in wikipedia. its title is Electron and light microscopical studies on the lung of one humped camel(camelus dromedarious).Dr doaa (talk) 07:04, 15 November 2008 (UTC)


 * You cannot publish your PhD thesis in Wikipedia. Wikipedia does not allow original research. A good way to publish elements of your thesis is to discuss with your supervisor and submit an article to a peer-reviewed journal. Axl  ¤  [Talk]  07:08, 15 November 2008 (UTC)


 * If you want to publish original research online you could take a look at arXiv. Mr.K. (talk) 11:31, 15 November 2008 (UTC)


 * There are a LOT of peer-reviewed journals out there; one is likely to accept your work for publication so long as it is really novel work. It might not make it into Nature or Science, but there is probably someone that will accept it.  Talk to your advisor, and see what he recommends.  --Jayron32. talk . contribs  17:10, 15 November 2008 (UTC)


 * You could create your own website, publish your thesis and put a link to it on your wikipedia user page. Lova Falk (talk) 18:07, 15 November 2008 (UTC)


 * Yes, but you could not use that self-published website as a source to cite in an article... It would still need to be published in a reliable source before Wikipedia could officially "recognize" it... --Jayron32. talk . contribs 21:52, 15 November 2008 (UTC)


 * Even though wikipedia can't accept original research, you may have written up some introductions where you wrote about other's research and you've probably documented this well with references. For instance the physiology of the camel could go into the camel article, but make a note on the talk page that it's you adding it, so people don't think it's someone breaching your copyright. If you've also taken pictures of the lung tissue, those pictures could be added to wikipedia. EverGreg (talk) 22:27, 15 November 2008 (UTC)
 * I wouldn't expect the style of a PhD thesis to be appropriate for an encyclopaedia article, it would require substantial rewriting. --Tango (talk) 00:05, 16 November 2008 (UTC)

air compressors - energy required.
I want to know the energy(electricity,KW-H) usage rate for air compressors. Compressor: Centrifugal, Displacement = 1000 CFm, output pressure rating = 100psi. Suppose, the out put flow required is 500 CF per Minute. Then, what would be the power consumed in an hour. The compressor motor rating is 250 HP. Is there any thump rule or simple formula to find it out..? Whether the equation, P1.V1 = P2.V2 is applicable here..?(P1 = Atmos. pressure, P2 = 100psi. and, V1, V2 are volumes). —Preceding unsigned comment added by Ajivg1 (talk • contribs) 12:39, 15 November 2008 (UTC)


 * This depends on its efficiency, but 50 percent is probably a reasonable guess. 250 HP would correspond to 500 HP *(0.746 kilowatts/HP) = 370 kilowatts. That is, every hour it would use 370 kilowatt-hours. -User: Nightvid (unregistered) —Preceding unsigned comment added by 129.2.43.42 (talk) 15:10, 15 November 2008 (UTC)
 * The Centrifugal_compressor Is running at half-capacity though..."all 250 HP" isn't being used. At least for the compressor side of things (setting aside inefficiencies and the motor itself), Ajivg1 is on the right track for a first-principles approach. Need to figure out how much work (== change in potential energy) is being done to compress a certain amount of gas by a certain amount. See Isothermal process for example. DMacks (talk) 21:27, 15 November 2008 (UTC)

Neurotransmitters
This came up recently in class and not even the PhD qualified teacher could think of an answer - why do we have so many different neurotransmitters? Apart from having different receptors which is a cop-out answer, we got so far as to say it was probably just an evolutionary mid-stage? RHB - Talk 15:49, 15 November 2008 (UTC)


 * What do you mean by "evolutionary mid-stage"? There is no destination in evolution, so I can't see how it's meaningful to talk about being half-way there. --Tango (talk) 16:57, 15 November 2008 (UTC)


 * The best answer I can think of is that we don't want any "bleed though" between the different functions of the brain. If we had only one neurotransmitter, then it could possibly "leak" into synaptic junctions where it would cause all sorts of havoc.  With a wide array of neurotransmitters, each localized to a certain set of cells in the nervous system, there is less chance of "cross contamination."  Although, the better answer is "because it works"; remember that evolution is not an intelligent process.  Stuff gets preserved in the system only because it doesn't self-eliminate.  Anything which does not cause insta-death is likely to be preserved by the system, not because it is the best possible way to do it, but because it works.  --Jayron32. talk . contribs  17:07, 15 November 2008 (UTC)

As a metaphor, you could compare with colors. All information that colors contain can be expressed in binary codes, but it is far more efficient for us to see the color red, green, yellow or blue than to process 001001, 010001, 110111, or 100011.Lova Falk (talk) 19:39, 15 November 2008 (UTC)
 * My guess (maybe a bit like Jayron32's idea) is that at every single moment there is an extremely complicated activity going on in the brain, with lots and lots of processes simultaneously that influence each other. Every single movement, every single sensation, every single thought (and each thought also elicits some memory, some emotion), the arcadian rhythms, just to name some examples, all have their neural base. I think to have different neurotransmitters is far more efficient for the brain than to have only one.
 * It's not just "different receptor for different transmitter" in a lock'n'key sense. You also get different binding affinities and have to have different degration/re-uptake mechanisms. That means different neurotransmitters can be quicker- or slower-/longer-acting than others. DMacks (talk) 20:52, 15 November 2008 (UTC)


 * Yes, these are largely the reasons. Different neurotransmitters bind to different receptors, and therefore affect conductances of different channels on different time-scales. For example, glutamate activates NMDA (depolarizing, slow) and AMPA (depolarizing, fast) channels; acetylcholine binds to muscarinic receptors (G protein coupled, several distinct types) and nicotinic receptors (ionotropic, again several distinct types); etc... Also, different types of synapses exhibit different short- and long-term plasticity, and therefore form connections differently during development and change differently during learning. This is required for a normal development and function of a complex nervous system (say, of a vertebrate, arthropod, or cephalopod). --Dr Dima (talk) 21:55, 15 November 2008 (UTC)

in theory, could a discovery about reality invalidate the possibility of physics as a field of science?
In theory, though it's ridiculously unlikely, the entire field of mathematics could be invalidated by the discovery that no system of axioms could fail to be inconsistent, and that for any set of mathematical assumptions, there exists no p such that p can be proven using those assumptions, but not p cannot be also be proven.

Does the same thing exist in physics? Could any results (however ridiculously unlikely) completely invalidate for physicists the very possibility of physics as a science?

I'm thinking, if Einstein or Maxwell, or any other scientist, were in a coma, and for whatever reason on a long opium trip (a la Kublai Khan), living in a dream-world much like anyone's who dreams, then if they decide to do experiments in their dream, or any other rigorous analysis of their new world, they would soon conclude that whatever has happened to reality, it has invalidated the pursuit of physics forever. Outside of dreams, however, could reality (though this is ridiculously unlikely) produce any experimental results that completely invalidate the very idea of physics? —Preceding unsigned comment added by 83.199.126.76 (talk) 16:35, 15 November 2008 (UTC)


 * Physics (and the rest of science, by extension) is based on the assumption that the universe can be explained. That is, there is a fixed set a physical laws that govern how the universe behaves. If it turns out that that isn't the case, and the universe just makes things up as it goes along, then the whole of science goes to pot. However, all our observations so far seem to support the assumption, so it's extremely unlikely. --Tango (talk) 16:55, 15 November 2008 (UTC)


 * There's not a single "lynch-pin" that holds up all of science which, if shown to be incorrect, would bring the whole thing down like a house of cards. It just doesn't work that way.  Sure, individual ideas are constantly being refined, but none of those ideas is SO important and SO key to the entire process would be rendered wrong.  Science is descriptive not prescriptive and as such, it doesn't depend on being "right" all the time.  If God came to earth and said "Look guys, I was just kidding with all those laws of physics, here's a new set of laws.  Work it out!!!", it would not invalidate all of the old laws, since they worked very well to describe the universe as it existed at that time.  Science would adapt to take in the new set of data.  --Jayron32. talk . contribs  17:03, 15 November 2008 (UTC)
 * Then phsyics is in direct contrast with mathematics, in which when an old result is overturned, it is not the case that this does "not invalidate the old result, since it worked very well to describe the truth as it existed at that time." —Preceding unsigned comment added by 83.199.126.76 (talk) 17:31, 15 November 2008 (UTC)
 * Old results in mathematics aren't overturned, they're just built upon. Once something has been proven, that's it, it's not going to suddenly turn out to be false after all. (There is always a chance the proof will be incorrect, but once it's been checked by a decent number of mathematicians you can be pretty sure it isn't, and there is always the standard caveat from Godel, but that makes no difference to day-to-day mathematics.) --Tango (talk) 18:02, 15 November 2008 (UTC)


 * (ec) The most fundamental idea of physics is that is there are fundamental laws of nature that can be discovered through application of the scientific method. New laws are discovered, or old laws modified, when new data is provided by experiment.  The important feature of a law of nature is that it universally true at all places and in all conditions.  More extreme experiments test the boundaries of the applicability of what we believe the laws to be and occasionally they have to be updated as a result.  An example is Newtons law of gravity being modified by Einstein's general relativity.  But always a new set of laws is put in place that is now universally true in the new set of data.  The foundation of science requires that such a set of laws exist - it is the unprovable act of faith in science if you like.  It is logically possible that a discovery could be made that showed that such a set of laws, however formulated, could not exist in all circumstances.  This would certainly invalidate the basis of physics, but I would be hard pressed to think of any way such an experiment could ever be performed.  Sp in ni  ng  Spark  17:09, 15 November 2008 (UTC)


 * I think the point is best made by talking about what happened to Newton's laws of motion when Einstein proved them "wrong" with relativity. Physics can't be completely wrong because they predict reality with such great precision - but they certainly can (as happened with Newton's laws) be shown to be missing some important terms that only show up under conditions that we have not yet fully explored (in that case - it was the fact that Newton had not explored the nature of light adequately).  There were times in past history (eg with Aristotle's laws of motion) where the laws were simply wrong (certainly true with Aristotle's stuff) - but those were always in times when the modern scientific method was not being employed.  The ancient Greeks actually frowned upon the idea of doing experiments and making measurements.   Modern science really doesn't allow us to make such gross errors.  Once we have a law that explains a large swath of phenomena - and which makes predictions that actually come true - it's exceedingly unlikely that the law can be utterly wrong - except in realms of mass, speed, size, temperature - that we have not carefully explored.


 * The situation is actually rather similar in mathematics. Godel showed that any sufficiently powerful logical system will allow theorems that can neither be proven nor disproven.  This is a profound (and disheartening) conclusion - but mathematics didn't end on that day - neither did very much of the theoretical or practical applications of mathematics collapse.  It works too well for that kind of major collapse to happen.


 * And in physics - we discover that at it's heart, quantum theory says "it's all just random anyway" - and that devastating blow to the idea of the "clockwork universe" didn't really make a dent in other areas of physics. Sure, we know that in principle a massively unlikely quantum event could cause a grand piano to spontaneously materialise in the middle of my subtle experiment to find an extrasolar planet - but that fact doesn't alter the validity of that experiment in any important way - so it can be neglected.  If string theory were proven true (or false...either would be profound) - our fundamental understanding of absolutely everything would change - but Hooke's law of spring stiffness wouldn't change - we could still rely on Ohm's law.   That's because whatever this new theory is, it has to explain WHY voltage, current and resistance behave as they evidently do.  The new theory can't say that for "normal" conditions Ohms law is wrong - because we've shown (and continue to show) that it must be correct because our computers are working OK.


 * Physics (and science in general) is about two things: "HOW things behave" and "WHY they behave like that". The "WHY" part certainly can (and does) change...but the HOW part can only change in such a way that's consistent with all of the 'HOW' laws we already have.  We can say that what we thought were quarks and photons and electrons and such are really only vibrating 26-dimensional strings...but that change to our understanding of "WHY" can't take away the indisputable fact that HOW "electricity" flows along copper wires is according to I=V/R.   Of course it's possible that the string theory might produce the discovery that Ohms law should really be:  I=V/R+0.00000000000000000000000000000000000000001xP/L where 'P' is the charge on the electron and L is the amount of time elapsed since the big bang - but this would hardly be a profound 'HOW' change - only a profound 'WHY' consequence - and most people would not do physics much differently as a result.  That's what happened to Newton's laws of motion.  We discovered this bizzaro thing about the speed of light and that space-time is distorted by gravity fields and the changes to Newton's laws all end up being modified by this factor of (1-v2/c2) - but since for almost all practical purposes, v2/c2 is just about zero - so the 'modification' is essentially nothing.  Physics changed radically - but it made absolutely zero difference to all of that beautiful victorian science that taught us how to make steam engines and such.


 * SteveBaker (talk) 17:41, 15 November 2008 (UTC)


 * I think SteveBaker has most of this correctly, but I firmly but respectfully disagree with his assessment of the difference between "why" and "how". All physics describes is the "How's".  For example, one can describe "how" light is generated from a heated object blackbody radiation and also "how" photons and electrons interact to produce that light and also "how" the way the universe organized itself after the big bang led to the creation of photons and electrons.  However, the big "why" questions, such as WHY the laws of the universe work the way they do, WHY it was created in the first place, WHY humans exist to study it; etc. etc. are entirely unanswerable via science.  Which is OK.  Science is not equipped to answer these questions, and never has and never will be.  But that does not make science invalid; rather science is the best system we have to answer the "how" and "what" questions.  See the works of Stephen J. Gould especially Rocks of Ages and The Hedgehog, the Fox, and the Magister's Pox for more on these ideas... --Jayron32. talk . contribs  20:15, 15 November 2008 (UTC)
 * I disagree - Science does have two parts, the hows and the whys. The scientific method involves making some observations, finding a law to describe those observations (a "how") and then coming up with a theory to explain that law (a "why") and predict further laws which you can then test. --Tango (talk) 20:31, 15 November 2008 (UTC)
 * Oh yes, science does have those two parts. Laws answer the "what" question by describing the world, and theories answer the "how" questions by explaining the world.  However, the big why questions, such as "Why does the universe exist at all" are not answered beyond "just because".  Science is not equipped at all to answer these questions.  We can answer HOW the universe exists (i.e. the Big Bang brought it into existence), but we can't answer "For what purpose does the universe exist (i.e. WHY)."  Any answer to that question, including the default "there is no purpose at all" are not testable by science, and so lie outside of the realm of scientific discipline.  They are real questions tied to the human experience, and their answers cannot be gotten by any known aspect of the scientific method, be it experimentation or inference from observation.  You are perfectly justified in coming to the "there is no purpose" conclusion, but science lacks the ability to back up that conclusion... --Jayron32. talk . contribs  20:46, 15 November 2008 (UTC)
 * That's just semantics. I'm pretty sure you and Steve agree, you're just using different words to describe the same thing. --Tango (talk) 21:07, 15 November 2008 (UTC)
 * You're probably right on that. I just wanted to make clear that science does not answer ALL questions about the human experience, nor does it try to.  It is incorrect to assume that some great revelation about "why the universe exists" (as opposed to "how it came into existence") would invalidate a single scientific observation, law, or theory... --Jayron32. talk . contribs  21:49, 15 November 2008 (UTC)


 * Science isn't good at the really HUGE "why" questions. We truly don't know why the charge on the electron is -1.6x10-19Coulombs - we may never know that.  We do know (to a pretty amazingly deep degree of explanation) why the DNA of humans is so similar to that of chimpanzees.  We know why putting my 20kg kid on one end of a seesaw (aka teeter-totter) requires me to put my friend's 40kg kid at half the distance in order for them to balance.  I can talk about the details all the way to the structure of the wood in the cross-beam and how the various nuclear forces make that work.  It's an amazingly detailed understanding.  However, to say that physicists aren't in the business of finding out WHY the charge on the electron is what it is - that's crazy talk.  If we thought we had a shot at figuring that out - we absolutely would.  The only reason we aren't working hard on the problem is that we don't have a clue how to approach it.  Worse still - every time we answer a pretty tough "why" question - we're just handed another deeper one hidden beneath it. SteveBaker (talk) 00:59, 16 November 2008 (UTC)


 * God could prove he exists and decide to actively meddle with reality. For science to work, you pretty much have to assume that "God did it" is never the explanation for any observable event.  Dragons flight (talk) 21:56, 15 November 2008 (UTC)
 * Unless you assume that God did everything, and science merely describes what He does in fine detail... --Jayron32. talk . contribs 00:36, 16 November 2008 (UTC)


 * Yes - although we also have to assume that (for example) we're not just simulations of humans inside "The Matrix" in a universe that bears no resemblance to ours...that the exterior world really exists at all...that I'm not just an abstract intelligence who is imagining all of you guys (along with the rest of the universe)...that, that, that...well, there are an infinite number of other things that we have to assume are untrue. It's easier to simply stop worrying about all of the things for which there is zero evidence and get on with trying to understand what we CAN perceive.  Occam's razor - it's the only sane way to proceed. SteveBaker (talk) 00:59, 16 November 2008 (UTC)
 * This is more than just Occam's razor - it's a matter of falsifiability, it's not just that we don't have any evidence about them, we can't conceivable ever have any evidence. If something isn't falsifiable, then it isn't within the realm of science and should be left to the philosophers (who should them be confined to a padded room for their own protection). My favourite possibility - it's not that you're imagining all of us, but that you're being imagined - try and get your head round that! --Tango (talk) 01:17, 16 November 2008 (UTC)


 * The problem (as relating to our OP's question) is that "unfalsifiable" doesn't mean "not provable" - it means "not disprovable". If seven billion pineapple and ham pizzas were to materialize out of thin air on Wednesday lunchtime - one for every man, woman and child on earth (with a few to spare to have with beer for breakfast the following day) - then this could be taken as almost certain evidence that the IPU(pbuh) really exists.  There is always a possibility that we might find proof that we are all inside "The Matrix" (eg if there was evidence of numerical roundoff error in some seemingly fundamental process...I could imagine a really cool explanation for Quantum Theory that centered around roundoff errors in the computer that's simulating our universe).  Proof of existance of IPU(bbhhh) would certainly make a significant dent in modern science - but it wouldn't change Ohms law - perhaps it would be found that Ohms law works the way it does because She(mhhnbs) requires it to be so - but the fundamental laws would stand and science could continue to discover more about how She(bbhhh) chooses to run the universe.  (We atheists would have SERIOUSLY conflicted emotions if THAT ever happened!) SteveBaker (talk) 02:01, 16 November 2008 (UTC)
 * Which is the whole point. If the Invisible Pink Unicorn exists or not, it wouldn't effect science one iota.  Science only describes the world as it is, but it does not attempt to explain the big questions of "Why are we all here, and why did things turn out exactly this way".  Even the default answer of "there is no reason, its all random" or "we do exist, so it doesn't make any sense to presume that we wouldn't" or even "The Invisible Pink Unicorn has made it so."  The problem is that science is silent on these issues.  I can have a full understanding of Evolution and Big Bang and fully accept these as scientifically valid and completely true understandings of how the universe works, and also have a full and complete relationship with God and the two ideas in no way conflict with each other... --Jayron32. talk.

contribs 02:29, 16 November 2008 (UTC)


 * I disagree that science doesn't attempt to explain the big questions - I think it does - but doesn't necessarily succeed at it because these answers so often seem out of reach. Also, as soon as we do explain something - it's not a big question anymore.  Figuring out "where people came from" is a big question - and we pretty much have a check box in there.  I think that by making god or gods unnecessary in our description of the universe around us - we've effectively answered that question.  We can pretty much explain everything beyond maybe the first picosecond after the big bang to the present without requiring any intervention from supernatural beings.  I'm sure that we'll shrink that one tiny moment in time when gods could have done something so a smaller and smaller slice.  Removing it utterly may be harder - but I'm more than satisfied that there are no more gaps for gods to hide in.  Perhaps they roll the dice for quantum mechanics - but since the consequences of that action is limited to killing the odd laboratory cat - that's a pretty miserable role for a supposedly omnipotent being.  Perhaps it was the gods who decided the charge on the electron and the universal gravitational constant - but since the 'many worlds hypothesis' works pretty well (and explains a lot more than gods to) - we may assume that we're in THIS universe because of the anthropic principle.  SteveBaker (talk) 04:52, 16 November 2008 (UTC)


 * My point - which you seemed to have missed - is that the pink unicorn could suddenly become visible and decide that pi = 3, hydrogen atoms are now heavier than lead, apricot is the 21st element, and light goes twice as fast on Tuesdays. The original poster asked for "facts" that could destroy physics as a science.  My point is that the meddling of an activist God is such a problem.  Most people who are religious don't just believe in a watchmaker God who set everything up and then stood back to let physics run, rather most people believe in an intercessionary God who takes an active role to change things in response to prayer and some divine plan.  If God is actively rewriting reality in violation of physical laws, then that limits the applicability of physics.  If God were to do enough of that, the study of physics would be worthless because past experiments would no longer be predictive of future behavior.  Dragons flight (talk) 02:57, 16 November 2008 (UTC)

(unindent) The IPU cannot 'suddenly become visible' (she's the Invisible pink unicorn - that's WAY different from a mere mundane pink unicorn)!

There is a subtle difference between the OP's original question and where we've strayed in answering it.


 * The original question is about a profound discovery we might make - and proof of the existence of the IPU would be a good example of that. If we proved her existence - but she didn't do anything different as a result - then life goes on, science continues to probe the universe (albeit with a very different view of what's going on) - everything we already know continues to work - although we now have some very different underpinnings for why it works like that.


 * But that's a very different thing if the universe abruptly changed in profound ways like the value of pi changing as a result of a rare IPU intervention in human history. The OP asks what happens if we discover something profound - and that's different from something fundamental that we thought we understood well changing in an unexpected and profound way.  I can't conceive of a universe where PI is 3 - so I'm going to duck out on that speculation.  But the charge on the electron suddenly changing is perhaps something worth thinking about.  Of course if the value did change - we'd probably rather abruptly cease to exist for reasons I can't be bothered to speculate on...but if enough other fundamental numbers somehow changed so that we'd still exist and be able to function - what would happen?   I guess, initially we'd be running round like crazy trying to explain this incredible event - and if it's a direct IPU intervention - we'll never figure it out.   We'd add it to our pile of axiomatic facts about the universe - not only do we not understand why the fundamental constants are amicable to life - now we also don't understand why they periodically change in value and yet still remain suitable for our further existance.  We'd be puzzled by that - but the anthropic principle can still hold (although it's not too satisfying as answers go).

What would be very tough indeed would be if both things happened at once. The IPU turns up and changes the charge on the electron. Now we have to accept that not only is there some kind of supreme being - but also we're unfortunate enough to have one of the bloody annoying interfering kind that just trashes any hope we have of making progress as a species because we have this arbitary creature out there screwing us up at every turn. This would be an odd situation. It's tough to speculate. SteveBaker (talk) 04:52, 16 November 2008 (UTC)

I did some voodoo for fun as a kid. I poked a needle into a plastecine replica of my right hand and to my surprise and total horror an invisible cone created by an invisible needle appeared in my left hand and pricked it. I therefore conclude that we are in the MATRIX and though the laws of physics normally apply, the administrator of the hyper-computer we are simulated in sometimes takes the piss. I suppose it could have been a highly improbable quantum event. I was not taking drugs incidentally. Perhaps I am Neo. —Preceding unsigned comment added by Trevor Loughlin (talk • contribs) 04:08, 16 November 2008 (UTC)
 * Or you could have just been imagining it... --Tango (talk) 16:34, 16 November 2008 (UTC)


 * Certainly - without doubt! This is a typical utterly bogus story - just like the people who claim to be abducted by UFO's.  Trevor's response to this astounding thing doesn't fit the results.  Look - you go to all that trouble to try this out - you're clearly expecting, hoping even - that it works.  The slightest twinge or tickle in the hand would seem like proof to you - so that's why it "worked".  But here's what makes it seem bogus to me.  Had that happened to me - I'd not have shrugged my shoulders and gotten on with life!  Such a profound discovery demands something more!  So I guess I'd have closed my eyes and asked someone else to stick the pin in - I'd yell the moment I felt anything - and have my friend tell me if my yell coincided with sticking the pin in.   I'd want to know how far the effect works - does it work through walls?   Does it work if I'm a mile away?  How does the effect "know" to affect my hand and not someone elses?   Can I make a clay foot and get the same effect?   Can other things than sticking a pin in it produce an effect?   So many questions - yet we're lead to believe that you did it once, it "worked" and that was that.  It simply doesn't ring true.  This is bogus - utterly bogus. SteveBaker (talk) 01:28, 17 November 2008 (UTC)

What gets me is, -each generation thinks they know what reality is. Yet there are many examples in history of major paradigm shifts! Relativity, Evolution, Quantum Mechanics, and realizing that Greek mythology gods arent running anything just to name some. One book, by an author that sounded credible (I'll name the exact reference, as soon as I relocate it) mentioned how we know how it is across the universe because we know the way scientific laws work here. Now that's an Occams Razor!

Dr. Carefree (talk) 18:25, 16 November 2008 (UTC)


 * Well the thing is that those "major" shifts didn't affect anyone's daily lives very much. Sure, they changed our "understanding" of the universe - but not our practical interactions with it.  Most people experienced no changes to their lives whatever as a result of the discovery of relativity - the effect is so minor at 'human scales' that we did not have to go out and buy new alarm clocks for rail travellers that measured our speed and arranged to ring at the right time to get us to work!  Evolution doesn't really impact people's daily lives very much - there is no risk of your cat having T-Rex 'kittens' anytime soon.  Quantum theory isn't understood at the most superficial level by 99% of the population.  So sure - they are interesting and all - but the effects of these major new understandings are actually fairly small.


 * There is a good reason for that - as I've been trying to explain in previous posts to this thread - we already understood how wheels and pulley and weights and motors and...all that stuff...worked before relativity came along. Relativity is ONLY relevent at huge relative velocities.  Evolution is only (generally) important over very long timescales - and where it does impact us (things like drug resistant disease models) - these things came along LONG after evolution was well understood.  Quantum mechanics only affects VERY small things - and our ability to make things like flash memory that actually USES quantum theoretical effects required technology that was far out of our reach when we figured it out.  Since the start of the application of the scientific method (so let's rule out the ancient greeks and start this debate in the 1600's) - not one single major paradigm shift has replaced the earlier theory - it's only ever expanded on it in the 'corner cases' at the extremes of experience.  Even such major things as the abandonment of alchemy for chemistry didn't change what we understood about the effects of heat on substances for the majority of things that we heat up in most of our lives.


 * Quantum theory enabled flash memory development - that's caused a revolution in photography, music distribution, communications - HUGE parts of our lives have been revolutionized by cheap memory that doesn't "forget" when you turn it off. But does ANYONE attribute this to Quantum theory?  No!  They just assume that the technology fairies came along one night and made this possible.


 * SteveBaker (talk) 01:28, 17 November 2008 (UTC)

My vooodo experiment was not repeatable, when I had regained my composure and stuck the needle in it did not work, ever again. I was not expecting anything and had made the hand as an artwork. The simplest explaination would be some form of self-hypnosis. I try to make it seem like a joke, but it certainly was no joke at the time. The shape of the cone could not have been created naturally. The pricking sensation seemed absolutely real. It belongs with other unprovable phenomena such as stigmata, ghosts and UFO's. —Preceding unsigned comment added by Trevor Loughlin (talk • contribs) 03:37, 18 November 2008 (UTC)

Another one for the bird psychologists here...
What's going on with the parrot here? Anger thing or sex thing would be my guess. --Kurt Shaped Box (talk) 16:56, 15 November 2008 (UTC)


 * It could have just been trained to do it for some strange reason. --Tango (talk) 17:09, 15 November 2008 (UTC)


 * Yeah, that's certainly a possibility - though some of the comments left by other users suggest that this behaviour is not unique to that particular bird. I have very little experience with Amazon parrots myself, so I'm not really sure either way... --Kurt Shaped Box (talk) 22:53, 15 November 2008 (UTC)


 * Googling indicates that it may be a courtship ritual. They certainly mention the spread tail feathers and the strutting up and down the perch.  This would assume that the parrot is a male, of course, which (despite my name) I can´t judge.  --Cookatoo.ergo.ZooM (talk) 00:11, 16 November 2008 (UTC)


 * In my (very limited) experience deducing the gender of a bird from it's display of sexual behavior is highly unreliable. Particularly when it comes to captive ones.  Since this bird is not reacting to another parrot, there's not telling.  If it were your bird you could run a series of experiments to narrow down what sets off this behavior.  I for one take it as a given though that part of the answer is that the poor thing is lonely. (OR We used to have a female budgie that tried to **** anything and everything, including another female we had boarding for the holidays. She viciously attacked a male we tried to introduce.  When we tell the story we find that more often than not other people who had/have birds are not the least bit surprised but nod and relate similar stories.)  Since parrots can be very playful it may also just be playing "peekaboo"  76.97.245.5 (talk) 06:37, 16 November 2008 (UTC)


 * I think that I may have solved this one myself. Take a look at this video of a female Amazon of the same species 'in heat', as they say. Notice the similarity of her vocalizations to the sound of a drawer being open and shut... Could that be it, do you think? --Kurt Shaped Box (talk) 10:16, 17 November 2008 (UTC)

Conservation of momentum
Okay, let's say you were hanging off a cliff, attached to a rope which is wrapped around a pulley attached to the edge of the cliff, and the rope is connected to a large rock (there's also no gravity). If you were to pull on the rope, obviously you would start rising and the rock would start moving. But how would momentum be conserved? The magnitude of your momentum is the same as the magnitude of the rock's momentum, but their in different directions.


 * The planet to which the pulley is firmly bolted is a part of the 'system'. It moves in the opposite direction to you and the rock...albeit rather slowly! (And this is true whether or not we are ignoring gravity)  SteveBaker (talk) 20:02, 15 November 2008 (UTC)
 * How do you hang without gravity? --Tango (talk)
 * Maybe not hang, but the point is that you're not moving. And I don't see why the planet would move. —Preceding unsigned comment added by 76.69.241.185 (talk) 20:59, 15 November 2008 (UTC)
 * The pulley imparts a force on the rope, so there is an equal an opposite force on the pulley, which is attached to the planet. I still don't understand the scenario, though... --Tango (talk) 21:05, 15 November 2008 (UTC)


 * Why wouldn't the planet move? It's not fixed in place.  When you pull the rope - there is a downward force on both ends of the rope (due to your inertia and that of the rock) - that pair of forces push down on the pulley - the pulley pushes downs on the bolts - the bolts push onto the cliff-face and the cliff-face pushes onto the planet.  F=mA applies to planets just as it does to you and the rock - so if you and the rock have a combined mass of (say) 100kg - and the planet (Earth, for example) has a mass of 5,000,000,000,000,000,000,000,000 kg - then if you and the rock move upwards at (say) 1 meter per second - then the planet MUST move the other way at 100/5,000,000,000,000,000,000,000,000 meters/second.  That's Newton's third law - and planets are not exempt from it!  You don't notice the planet moving because 0.0000000000000000000002 meters/second is pretty amazingly slow - but it most certainly does move - and it does so in exactly the way necessary to keep the center-of-mass of the earth/you/rock/pulley/rope system exactly stationary - which conserves momentum.  Anyway - whether you happen to believe it or not - that IS the correct answer to your question!


 * If it helps - imagine the pulley is not fixed to the planet - in fact, there is no planet. You, the rock, the rope and the pulley are just floating in space.  As you pull on the rope, you and the rock move S-L-O-W-L-Y towards the pulley - but the lightweight pulley comes flying at you at great speed!   Now imagine the pulley is bolted to a 100lb anvil - when you pull on the rope, you and your rock go towards the pulley and the anvil - and the pulley/anvil come slowly towards you.  Keep doing this experiment with bigger and bigger things bolted to the pulley - and pretty soon you are imagining an entire planet bolted to the pulley.  There is no point at which the rules changed...planets aren't special when it comes to the laws of motion.


 * SteveBaker (talk) 23:09, 15 November 2008 (UTC)

transistor configuration116.71.178.160 (talk) 20:33, 15 November 2008 (UTC)
i am going to make this http://www.redcircuits.com/Page38.htm project .but i dont know that how the transistor Q3 being used in the circuit is baised and why it could control the amplitude of louder sound in a limit while allowing all little sound fully amplified. plz.plz.plz.plz.plz.plz.help me]
 * Wow. I would have to dig out some circuit analysis books from the attic. Anyone current on the use of voltage divider and diodes in biasing a base?Edison (talk) 05:13, 16 November 2008 (UTC)


 * The diode D1 is acting as a peak detector and the resulting dc biases the base of transistor Q3. As this dc is proportional to the sound level the output of Q3 proportionatly decreases, this output is then low-pass filtered by R6/C4 and passed to transistor Q1 via resistor R2.  This provides bias to the base of Q1, increasing sound level driving Q1 nearer to cut-off and thus reducing the gain.  The purpose of the whole loop is for agc.  Sp in ni  ng  Spark  01:58, 17 November 2008 (UTC)


 * Agree. The gain of Q1 is altered by altering its emitter current and hence its Re. This is achieved by Q3 passing a dc value proportional to the signal amplitude back to the base of Q1. This is a typical agc circuit found in many transistor radios.--GreenSpigot (talk) 02:13, 17 November 2008 (UTC)

photoelectric cell
is photoelctric cells can oparate on shorter waves than normal light like uv x-rays and gama radation or mabe longer waves?--אזרח תמים (talk) 20:44, 15 November 2008 (UTC)


 * Photoelectric cells individually have a wavelength at which they are most efficient. Based on choice of materials, that can generally range from ultraviolet to near infrared. By stacking cells with different optimal wavelength on top of each other, it is also possible to create efficient absorption across a wider range. In general, gamma rays are too high energy to be captured by normal photovoltaics. Dragons flight (talk) 21:39, 15 November 2008 (UTC)

bat some of the photons most be catch in no?--אזרח תמים (talk) 16:10, 17 November 2008 (UTC)

Rainfall runoff through a four inch pipe
I'm no engineer, but....Given a roof area of 1000 sq. ft. I understand that 1 inch of rain will create 625 gals of water. I've also read that a 4 inch pipe can carry 160 or 195 gals. per min. at(I think)a flow rate of 5 ft.per sec. I live in New England and am wondering about how many inches of rain per hour, perhaps combined with snow melt, would  it take to overwhelm the pipe? At three inches of rain per hour, which I would think would be extraordinary, am I correct that I would get about 1900 gals. of rain per hour which, if evenly distributed, would give about 31 gals. per min. It seems like a 4 inch pipe would be plenty big enough. Also how do I calculate flow rate through the pipe or is it even necessary? Thanks for any help. —Preceding unsigned comment added by 98.229.160.179 (talk) 21:34, 15 November 2008 (UTC)


 * My experience with the (often spectacular) Texas rainstorms is that no system you could devise would take care of it. Four inches in an hour is quite common here - and we've had 14 inches overnight on one occasion a few years ago.  Most Texas homes don't even have guttering and down-spouts.  The problem with that amount of water doesn't seem to be the capacity of the pipes - but the speed that the water comes off the roof.  It comes down so quickly that it completely overshoots the guttering and spills over the edge.  Also, no matter how clean you keep your guttering - in a good storm, leaves are blown off trees and can block the guttering so quickly that the gutters will block before they get to do their job.


 * But I can't fault your math - in theory it should be OK. This page suggests the most rain you'll see would be around the same as the worst Texas can do - and the worse you'll see anywhere in the USA is around 164mm/hr (about 6 and a half inches in an hour!)...of course snow melt might make for more runoff than that.  But even at that rate, your downpipe is only operating at half capacity.


 * Calculating the flow rate through the pipe is tough - but because gravity is accelerating the water as it falls, the limiting factor is how fast the water can get through the hole at the top of the pipe - once it's in the pipe - the water beneath will be moving faster - so if anything, it'll get sucked down. Probably the biggest upgrade you could do would be to have some large funnel-like contraptions at the tops of the pipes.


 * A bigger concern is the guttering - it's only a half-cylinder - so it has only half the volume of the down-pipes - and since they slope so gently - there isn't much help from gravity to get the water moving down the gutter.  Where the gutter meets the downpipe is the worst place.  So I would suggest that you use more down-pipes rather than making the down-pipes bigger.


 * SteveBaker (talk) 22:50, 15 November 2008 (UTC)


 * I'll just note that if this is a practical question rather than a theoretical one, your local building codes may have something to say about it. --Anonymous, 05:20 UTC, November 16, 2008.


 * Another good reason to get more down-pipes is that if one section of your gutter gets clogged the water has another way to go than over the edge of your gutter (some of it will anyway). Also if you run into a problem with the working of a section of the gutter you only have to fix the section between downspouts. (But do check with your building code and don't utterly ruin the appearance of your house.  You might want to sell it some when.)76.97.245.5 (talk) 05:31, 16 November 2008 (UTC)
 * Wouldn't you have a problem with the fact that the gutter can only be tilted downwards in one direction? I'm not sure what angle of tilt is required for guttering to work effectively, but if it's too great (how great depends on the distance between downpipes) the water would overflow and some point downhill from the downpipe and the downpipe would be useless (it could still be useful for the guttering coming from the other direction, of course). --Tango (talk) 16:32, 16 November 2008 (UTC)

Effects of global warming on microbes
Hi. Have any studies been done on the effects of global warming on important species of microbes, especially those that act as the basis of some ecosystems? Is there an article on this? If so, what have such studies concluded? Thanks. ~ A H  1 (TCU) 21:38, 15 November 2008 (UTC)


 * See Effects of global warming for an introduction to the topic... --Jayron32. talk . contribs 21:44, 15 November 2008 (UTC)
 * I don't see anything about microbes, and by that I mean the extinction risk posed to certain key microbes, which is not covered by extinction risk from climate change. ~ A H  1 (TCU) 21:54, 15 November 2008 (UTC)


 * I think it's pretty unlikely that they would become extinct. They have really short reproductive cycles and (typically) their DNA replication mechanisms are primitive so that DNA transcription errors are common.  They have massive population sizes - so the probability of a beneficial mutation showing up is high.  This allows them to evolve and adapt spectacularly quickly (in a matter of days in some cases).   Larger plants and animals have a harder time.  Our live spans are long - so we might only have a couple of generations before the problem kicks in - and our DNA transcription mechanisms have built-in protection against copying errors that means that we don't mutate easily.  There are so few of the larger lifeforms (compared to bacteria at least) that there are comparatively few 'mutants' who might provide a source of evolutionary improvements.


 * It's also the case that the simpler lifestyle of bacteria allows them to adapt radically - there are 'extremophile' bacteria pretty much everywhere we look - but only a very few species large plants and animals can survive near volcanoes or hot-springs or in ice/snow conditions.


 * "Extinction" is a slippery term. If some precise species of bacteria exists today - but due to changing environmental pressure is completely evolved into a new species in 5 years from now - did it "become extinct"?  The question is not whether they'll survive (they will) - but what impact will their evolution have on us?


 * So I'm pretty sure that bacteria will adapt quickly, easily and smoothly to the worst we can do to them - and whether we call that "extinction" is just a matter of language.


 * If useful bacteria (like maybe gut flora) evolve to prefer to live outside the human body then maybe we're in deep trouble. If disease bacteria evolve faster than in the past under the pressure of climate change - we're in trouble.  So they'll be fine - but maybe we'll be in even more trouble than we expect...it's not easy to know.


 * SteveBaker (talk) 22:25, 15 November 2008 (UTC)