Wikipedia:Reference desk/Archives/Science/2012 September 9

= September 9 =

Unidentified larva
I am struggling in the identification of this insect found on a wall in the Pantanal. It might be a larva of a bagworm moth or maybe of Phereoeca uterella. However, it seemed that there was no “worm” inside like in these and those pictures, but it still moved. Any ideas? --Leyo 00:42, 9 September 2012 (UTC)


 * I think you have just won the prize for most hopeless question of the month. Looie496 (talk) 03:37, 9 September 2012 (UTC)


 * Looks like a louse nit or, especially, the unhatched egg of a fly, which might move just before hatching. Makes me want to retch looking at it. μηδείς (talk) 04:10, 9 September 2012 (UTC)


 * How long is this egg? Here are images related to fruit fly pupae. Please specify. μηδείς (talk) 21:48, 9 September 2012 (UTC)


 * It's not an egg. It moved slowly. It is 1–2 cm long. --Leyo 21:10, 10 September 2012 (UTC)


 * Are we sure this isn't a slug of some sort? -- Jayron  32  21:17, 10 September 2012 (UTC)


 * Yes, I am. It has a casing made of sand. --Leyo 22:54, 10 September 2012 (UTC)


 * How long is it? μηδείς (talk) 03:11, 11 September 2012 (UTC)


 * Still the [//en.wikipedia.org/w/index.php?title=Wikipedia:Reference_desk/Science&diff=prev&oldid=511750300 same]. --Leyo 08:49, 11 September 2012 (UTC)


 * I'm sorry, I don't see how I missed that. μηδείς (talk) 21:11, 11 September 2012 (UTC)


 * You own identification seems correct to me, as it looks just like those pics. I suspect it does have a larva inside, you just didn't see it (perhaps it retracted when you touched the casing). StuRat (talk) 08:58, 11 September 2012 (UTC)


 * Yes, I went through this very identification myself some years back. Plaster bagworm was the common name, IIRC.  Something about them liking fresh (or not so fresh) plaster. ¦ Reisio (talk) 04:04, 13 September 2012 (UTC)


 * @StuRat&Reisio: Thank you. I renamed the image and added it to the article. --Leyo 08:07, 13 September 2012 (UTC)


 * OK, let's mark this resolved. StuRat (talk) 08:13, 13 September 2012 (UTC)


 * I was made aware that according to this website it might also be Praeacedes atomosella: “It is possible that records of P. uterella might be misidentified as this species or viceversa.” --Leyo 10:10, 14 September 2012 (UTC)

Mental Capacities of Prenates and Infants Versus Those of Certain Animals
How do the mental capacities of prenates and infants compare with those of certain animals such as pigs, chickens, and fish? BTW, by prenates I meant prenatal human specimens--zygotes, embryos, and fetuses. Futurist110 (talk) 06:18, 9 September 2012 (UTC)
 * Unfortunately the only way we have to measure mental capacity is to give various sorts of stimuli and look at the responses. Just about the only response a fetus can make is uncoordinated movement -- and just about the only mental capacity we can recognize is a tendency to move in response to movement by the mother or to loud sounds.  Newborn infants can make some basic coordinated movements, but the most sophisticated thing they can do is move their eyes.  Their eye movements say that they that they can make some interesting distinctions, for example between faces and other types of objects.  Also the sophistication of their responses increases rapidly with age.  But basically, the motor control capabilities of adult animals such as pigs and chickens are so much better developed than those of human infants that it's hard to figure out how to do a meaningful comparison. Looie496 (talk) 07:03, 9 September 2012 (UTC)
 * Winthrop Kellogg raised Gua (chimpanzee) with his son Donald, beginning when Gua was 7 1/2 months old and Donald was 10 months old. "Although the chimp progressed faster than the boy in the earliest stages, it became evident towards the end of the experiment that she was falling behind, especially ‘in the matter of intellectual adaptation to human demands’." Clarityfiend (talk) 09:36, 9 September 2012 (UTC)


 * I found Dogs as intelligent as two-year-old children. Alansplodge (talk) 22:57, 9 September 2012 (UTC)


 * Encephalization quotient? Also, parrots are supposedly as smart as a human six-year-old. Thus far, the wisdom and philosophy of dolphins is hitherto unknown. ~ AH1 (discuss!) 18:39, 11 September 2012 (UTC)

Basically all that a newborn has in the way of mental capacity is potential, since they haven't yet formed the proper associations and connections between sensation and motion. Newborns have been shown to react differently towards their mother's voices. They have rudimentary experience with touch. But they can't even focus their eyes at birth, let alone get up and walk around like chickens. Human mental capacity requires a lot of input and learning and physical growth and differentiation of the nervous system to develop. The brain isn't even like a computer that is just waiting for software to be loaded--it's wiring isn't even in place. You might look at child development and Jean Piaget, although these articles are concerned with developments after birth, and at Fetus, although it is far too concerned with abortion, rather than strict biology. μηδείς (talk) 21:27, 11 September 2012 (UTC)

Neurons and viruses

 * 1) How large are most (human) cerebral neurons compared to common viruses (say, the influenza A virus)
 * 2) How large are synapses between these neurons?
 * 3) Is it theoretically possible that viruses, after somehow reaching the brain, could place themselves between (or around) these synapses and cause an interuption between electrical impulses? If so, what problems could arise from this?

Thanks, 64.229.152.217 (talk) 06:19, 9 September 2012 (UTC)


 * The synaptic cleft at a chemical synapse is generally 20-40 nm wide, and the smallest viruses are only about 20 nm in length (although most are a good bit larger), so I suppose it is possible in principle, but I have never heard of anything like that happening. The goal in life of a virus is to inject its DNA into a cell so that it can exploit the cell's machinery to reproduce itself, and I can't see how fooling around in the synaptic cleft would do anything to promote that goal.  But it's largely a moot point:  because of the blood-brain barrier, viruses can't even get access to synapses unless something has gone very badly wrong. Looie496 (talk) 07:19, 9 September 2012 (UTC)
 * Neurotropic viruses like rabies infect nerve cells and spread neurally, thereby evading the immune system and the blood-brain barrier. These viruses pass through the synapses so in theory it is possible. That's assuming the infection is otherwise asymptomatic. Infection by some viruses result in degeneration of the neuron as a self-destructive defense mechanism to slow the spread of the virus. a virus blocking the synaptic cleft wouldn't matter much in that case.
 * Interestingly, neurotropic viruses could provide researchers an opportunity to trace connections among neurons. Tracers used in neuroanatomy research are limited in their ability because they don't cross synapses and in the past, after identifying neurons of interest, other techniques like electron microscopy were needed to further explore the interconnections between them. Neurotropic viruses could function as synapse crossing tracers, and they would be self-replicating. The paper was published in 1998, so this info is a bit dated. Ssscienccce (talk) 20:17, 9 September 2012 (UTC)


 * A protein in a misfolded form called Prion causes mad cow disease, but it is not a virus. -- RexRowan  Talk  19:13, 9 September 2012 (UTC)

Efficiency of Vaccinations against Hepatitis B
If you are concerned about how to interpret specific antigen numbers, or any other medical information, pertaining to your personal situation, please contact a doctor for a personal assessment. No one here can reliably provide that. -- Jayron  32  11:34, 9 September 2012 (UTC)

Comparative strength of fundamental forces
Sometimes we hear things like "gravity is times weaker than ", but how is that number calculated, given that different forces depend on different factors (e.g. charge or mass)? What exactly is being compared? 86.167.124.146 (talk) 11:30, 9 September 2012 (UTC)


 * Regardless of the what the force operates on, mass or electric charge or whatever, it is always a force, measured in some (tiny) fraction of a Newton, the unit of force (or measured in units of kilogram-force). Gravity causes two bodies having a finite mass to be attracted to each other by a force; two bodies each having an opposite electric charge are attracted to each other by a force.  Thus for any two bodies each having a certain mass, each having a certain electric charge, and separated by a certain distance, will be attracted (or repelled) by a net force being the sum of the gravitational force and the electric force.  Thus, for any two bodies having mass, charge, and a separation, the components of the net force are calculable and comparable.  Ratbone124.178.174.234 (talk) 13:16, 9 September 2012 (UTC)
 * Thanks, I understand all that, but that wasn't the question I intended to ask. The statements I am talking about are not comparing forces on some specific bodies with some specific charge or mass in some specific circumstance. They are saying (or purport to be saying) that gravity is times weaker in some absolute, or general, sense. Therefore the question arises as to what exactly is being compared. 86.167.124.146 (talk) 13:54, 9 September 2012 (UTC)
 * That doesn't make much sense. Which of the various forces are the stronger or weaker depends on the circumstances and distances between bodies.  Can you cite a reference where you saw this, or, preferably, if you have an online example, can you provide the url?  Ratbone124.178.174.234 (talk) 14:30, 9 September 2012 (UTC)
 * You can easily give specific values for a specific particle pair - electron and electron, or two sodium ions. But you are right that no general rule exists to get a solid number.  Yet... gravity seems weaker than electromagnetism.  An exercise I won't actually do right now would be to evaluate the strength of attraction between two Planck masses (thought to be the greatest mass a particle can have before collapsing into a black hole), compared to the strength of repulsion of two +1/3 charges (the smallest possible value I know of, for quarks).  I suspect this will indicate that gravity is very much weaker than electromagnetism even for the largest mass and the smallest charge. Wnt (talk) 15:14, 9 September 2012 (UTC)
 * No, the gravitational force between two Planck-mass particles with charge 1 is similar to the electromagnetic force between them. -- BenRG (talk) 23:32, 9 September 2012 (UTC)
 * Hmmmm... looking further, the Planck particle actually has the square root of pi more mass than the Planck mass. And they are really ridiculously dense - 4.90 x 1094 kg/m3.  I'm getting that the mass of the Earth (5.98 x 1024 kg), formed in contiguous Planck particles in fcc packing (0.74) would occupy 1.65 x 10-70 m3 - the area of a sphere with radius 1.58 x 10-23, or about 50 million times smaller than a proton.  That's dense!  Now anyway, for two identical particles 1 meter apart with this mass and charge 1


 * F = (3.86x10-8kg)2*(6.67x10-11N (m/kg)2/1 m2 = 0.99x10-25 N
 * F = (1.60x10-19C)2*(8.99x109N (m/C)2/1 m2 = 2.30x10-28 N


 * Unless I fouled up... Oddly enough, this ratio is 3.1415 x 137.01 ... so if we multiplied by that fine structure constant, and compare to the Planck mass rather than the mass of the Planck particle, the numbers become equal, within the low precision of this calculation. Not sure what that means... Wnt (talk) 04:26, 10 September 2012 (UTC)


 * It's a statement that gets made from time to time in popular science contexts. I could not give exact references. It's interesting though... arguably the greater electromagnetic force between charged particles shows that particles have vastly more charge than they do mass, rather than that gravity is weak. 86.167.124.146 (talk) 17:22, 9 September 2012 (UTC)
 * I think they are all measured against the change of velocity between the masses' interactions. -- RexRowan  Talk  17:48, 9 September 2012 (UTC)
 * The "strength" of an interaction is given by the value of its coupling constant. This is a dimensionless number (for electromagnetism, it is 1/137, the fine-structure constant) and is independent of which particles participate in a concrete interaction event. See here for a list of the values of the coupling constants (at low energy). In order to do calculations on particular events, the coupling constants are multiplied by the charges, masses, etc. of the particles involved. For a more intuitive approach, you can e.g. calculate the electric and gravitational forces between two electrons at a certain separation, but note that this changes when you replace the electrons by protons, for instance. --Wrongfilter (talk) 18:05, 9 September 2012 (UTC)
 * So, to be clear, is this coupling constant the unique way to describe the "absolute" strength of a fundamental force, independent of its action in any particular situation? It means, therefore, that we can say, for example, "gravity is times weaker than the electromagnetic force"? 86.128.4.46 (talk) 19:23, 9 September 2012 (UTC)
 * No, it's dependent, there must be an interaction between the known value of the masses to apply the constant. -- RexRowan  Talk  19:34, 9 September 2012 (UTC)
 * Are you sure you aren't confusing this with the gravitational constant? 86.128.4.46 (talk) 19:55, 9 September 2012 (UTC)
 * I don't know. I think the condition is there must be an interaction between the masses under the effect of a certain type of force to apply the coupling constant. For example, a stone and magnet both with mass but only have gravitational force with each other but no electromagnetic force so the coupling constant of electromagnetic force does not apply. -- RexRowan  Talk  19:34, 9 September 2012 (UTC)
 * Hey, try this, you can ask a real physicist here: --  RexRowan  Talk  20:02, 9 September 2012 (UTC)


 * They are talking about the force between electrons or protons. The difference is around 1037 for protons, 1043 for electrons, or 1040 for one of each. Asking "why is gravity so weak?" is the same as asking "why are electrons and nucleons so light?". -- BenRG (talk) 23:32, 9 September 2012 (UTC)
 * Are you disagreeing with Wrongfilter, who says there is a way to measure the strength of these things independently of any specific interaction event? 86.128.4.46 (talk) 00:49, 10 September 2012 (UTC)
 * I suppose I am. The electromagnetic fine-structure constant is defined in terms of the electron/proton charge. A corresponding unitless gravitational coupling constant would have to be defined in terms of a particular mass. If you picked the electron mass you'd get a value 1043 times smaller than the electromagnetic constant. But it doesn't make much sense to pick the electron mass since it isn't a fundamental mass the way the electron charge is a fundamental charge. Also, the whole thing is just a needlessly complicated way of saying that the ratio of force strengths for two electrons is ~1043. -- BenRG (talk) 03:34, 10 September 2012 (UTC)
 * I concede that the definitions of the coupling constants are to some extent arbitrary and the numbers are therefore indicative more than anything else. I don't know about "needlessly complicated". The force comparison works for electromagnetism and gravity, but how would you calculate the force due to the weak or strong interactions? The "strength" of an interaction manifests itself rather through interaction cross sections, decay rates and stuff like that, and in order to calculate those one uses the coupling constants (attached to the vertices of the Feynman diagrams, if I remember correctly). Also, the coupling constants are used to parameterize the dependence of the interaction strength on the interaction energy. Admittedly, this is probably more abstract than the original question intended. --Wrongfilter (talk) 12:14, 10 September 2012 (UTC)
 * Well, according to the calculation I did above, if you use the Planck mass, it appears the coupling constant is something pretty close to 1... Wnt (talk) 03:46, 11 September 2012 (UTC)


 * That's because that's how the Planck mass is defined - "Duh". In other words, the Planck's mass is chosen on purpose in such a way that the gravity's coupling constant will be about 1. Note that gravity is different from the other forces. It is possible to define a unitless fine structure constant for electromagnetism, weak, and strong interactions. That's not the case for gravity. Dauto (talk) 14:40, 11 September 2012 (UTC)


 * Hmmm, you do have a point there. And yet, I don't presently understand why this number is nearly the same as the much-publicized number for the largest possible particle that won't collapse into a black hole. Wnt (talk) 15:04, 12 September 2012 (UTC)


 * Please check out electroweak interaction. While gravity is understood in large scales, the microphysics of gravity remains a mystery for the quantum physisists to maul over. ~ AH1 (discuss!) 18:36, 11 September 2012 (UTC)
 * I hope you meant "mull" over. "Physicist mauled over theory" would be a very attention-grabbing headline. μηδείς (talk) 21:08, 11 September 2012 (UTC)


 * The weak coupling constant is actually larger than the electromagnetic coupling constant. The weak force is weak because of the large mass of the gauge bosons (which means they're always far off shell at ordinary energies). So this is not necessarily a good way of comparing the force strengths in practice. -- BenRG (talk) 17:05, 12 September 2012 (UTC)

speed of light and spin
I know that theoretically, if a particle travels at the speed of light, it shall be mass-less, otherwise it would have infinite energy. Should this kind of particle satisfy any other condition? e.g. should its spin have some certain value?--37.117.25.125 (talk) 14:52, 9 September 2012 (UTC)


 * This isn't my field, so caution, but - Photons are spin-1 particles and have an angular momentum of Planck's constant (well, its helicity in the direction of travel is that; there's a square root of 2 that enters into it which is beyond my understanding). The W and Z bosons also have spin 1.  But gravitons are believed to be a spin-2 particle, if they exist. Wnt (talk) 15:18, 9 September 2012 (UTC)


 * A particle moves at the speed of light if, and only if, it is massless. So you could rephrase your question as aking what special properties are required to be massless. The only phenomena I know of related to spin is that helicity and chirality will be the same; our article on chirality may be of interest to you, the helicity article is not so useful. To date the only observed massless particle is the photon, though the gluon is strongly suspected to be massless as is the graviton (if it exists), so all known massless particles are bosons; though, not all bosons are massless, the Higgs, W boson, and Z boson are massive. The standard model originally assumed that neutrinos (a fermion) were massless, and this wasn't conclusively disproven till '98 when flavour oscillations were observed in Japan; thus, as far as I can tell, there is no reason a fermion couldn't be massless, and hence travel at light speed. [If you don't know already, fermions have half-integer spins, bosons have integer spins.]Phoenixia1177 (talk) 09:47, 10 September 2012 (UTC)

Medical Examination Beds
Hello. What are those rings that doctors can pull and fold out from the sides of medical examination beds called? Thanks in advance. --Mayfare (talk) 15:33, 9 September 2012 (UTC)


 * I'm not sure what you're talking about, but this page has many examples, all with different names for different functions. --TammyMoet (talk) 16:32, 9 September 2012 (UTC)


 * I think your talking about stirrups, which are for holding the legs up and separated for vaginal examinations and the like. Dominus Vobisdu (talk) 16:42, 9 September 2012 (UTC)


 * Do please clarify. Do you mean this? μηδείς (talk) 21:47, 9 September 2012 (UTC)


 * I think they mean bed rails, like these: . They are meant to keep the patient from falling out of bed.  They fold down for examinations, to exit and enter the bed, etc., where they would otherwise be in the way.  They may also contain electronics, such as the nurse call button, bed adjustment controls, and TV/radio controls. StuRat (talk) 03:25, 10 September 2012 (UTC)

Snow in Muslim nations
Which Muslim nations do tend to receive snow during the winter season? — Preceding unsigned comment added by 65.92.155.47 (talk) 16:18, 9 September 2012 (UTC)


 * Iran gets snow in its mountains, enough for quite a few skiing areas. -- Finlay McWalterჷTalk 16:26, 9 September 2012 (UTC)
 * (ec)It depends how you define "Muslim nation." For example, Kazakhstan is a secular republic, but its population is about 70% Muslim.  It is a fairly arid place, but it has cold winters with snow.  The climate of the Islamic Republic of Iran is very diverse, but there are high-altitude basins, and numerous very tall mountain ranges; heavy snowfall is common in most of the country.  Afghanistan is very snowy, and last time I checked, it is officially an Islamic Republic.  And, I'd be remiss if I did not mention Lebanon... the Lebanese people are diverse, but there are many Muslims.  As I learned the etymology, "Lebanon" and "lebneh" both come from the same root-word, describing the snowy mountains.  Though, this is not in universal agreement.  In fact, a senseless war was fought over it. Nimur (talk) 16:42, 9 September 2012 (UTC)


 * The mountains of Pakistan, such the Pakistani parts of the Karakoram, get a lot of snow. -- Finlay McWalterჷTalk 18:10, 9 September 2012 (UTC)
 * There are the Caucasus mountains. μηδείς (talk) 20:07, 9 September 2012 (UTC)


 * This past February Bosnia and Albania were both hit by heavy snowfall, although this was unusual. Some parts of Turkey receive snow, as any reader of Orhan Pamuk will remember. Of course, there is a particular place in Dubai where it snows every night. L ANTZY T ALK 21:34, 9 September 2012 (UTC)


 * The IP seems to be from Canada, (Toronto per geolocate), which may explain the implied bias. μηδείς (talk) 21:44, 9 September 2012 (UTC)
 * What helpful information is conveyed by your comment on "implied bias"? Bielle (talk) 22:02, 9 September 2012 (UTC)
 * Um, the point of view that southern lands don't get snow? What in the world did you think I meant? μηδείς (talk) 18:40, 10 September 2012 (UTC)
 * That point of view might need readjusting. South America, Africa and Australia all get snow.  --  ♬  Jack of Oz  ♬  [your turn]  20:57, 11 September 2012 (UTC)

See Syria: desperate Homs residents collect snow to drink as water is cut off and SNOW IN JORDAN Weird but True. Alansplodge (talk) 22:34, 9 September 2012 (UTC)
 * And I found Bethlehem SNOW! - a mainly Christian town in the Muslim dominated West Bank. Alansplodge (talk) 22:42, 9 September 2012 (UTC)
 * On a roll now - It Snows in Alexandria (Egypt), Snowfall in Saudi Arabia and UAE's 'once in a lifetime' snow fall although the last sounds rather exceptional - there's a nice video of some chaps in traditional Bedouin robes building a snowman. Alansplodge (talk) 22:47, 9 September 2012 (UTC)
 * Afghanistan in particular is infamous for its deadly avalanches and cold waves. Also, if you count the Taklimakan Desert as a "Muslim region", then it has snowed there. ~ AH1 (discuss!) 18:34, 11 September 2012 (UTC)

Is it true that point particles like quarks and electrons have no volume?
Topic says it all. ScienceApe (talk) 17:01, 9 September 2012 (UTC)
 * I suspect that (a) the definition of "volume" becomes tricky at these scales and/or (b) no one really knows. No doubt someone will be along soon to give you a better answer! 86.167.124.146 (talk) 17:24, 9 September 2012 (UTC)
 * Please read Point particles. In standard particle physics, volume does not apply to points because it makes calculations easier when the result doesn't have to go to details. But in quantum mechanics which describes particles on a small scale, point particles are not points anymore, they have volume, mass and electrical charges, including strings. -- RexRowan  Talk  17:30, 9 September 2012 (UTC)


 * (ec)First off, by definition "point particles" have no volume. They're points - there's no width, length or depth to them, and as such, there's no volume. But then are quarks and electrons true point particles? The Standard Model (the most widely accepted and best validated theory of subatomic particles) treats them as such, although there are other theories (like string theory) which give them non-zero spacial extent (though offhand I'm not aware of ones which give them full 3D volume). But, as 86.167 indicates, you have to be careful about your definition of "volume". For instance, the Heisenberg uncertainty principle means it's difficult to pick out a single point in space where the particle is located - instead it's delocalized over a area - does that count as "volume"? Also, depending on how you set up the calculations, you can come up with a non-zero "size" of things like an electron (see classical electron radius), which means that the electron behaves like it has a non-zero volume (see also cross section (physics)) - does that count? -- 71.35.118.235 (talk) 17:46, 9 September 2012 (UTC)
 *  String theory posits that the elementary particles (ie. electrons and quarks) within an atom are not 0-dimensional objects, but rather 1-dimensional oscillating lines ("strings"). So, 1 dimensional objects still have no volume. Vespine (talk) 22:42, 9 September 2012 (UTC)
 * It should be noted that even atoms don't have a well-defined volume. Well, I suppose they do, but it depends on what definition of atomic radius you are working with.  -- Jayron  32  22:53, 9 September 2012 (UTC)


 * There are different notions of volume. The technical sense in which electrons are point particles (in the standard model) is that the electron field interacts with other fields (like the electromagnetic field) separately at each point. You can define a proton field too, but the value of that field at a point only tells you whether the proton is centered there. Since the proton has a small size, about 1 fm, that point of the field will interact with the electromagnetic field at points up to ~1 fm away.


 * On the other hand, the thing that prevents two objects from occupying the same region of space is the Pauli exclusion principle applied to electrons, so in that sense electrons do occupy space, if anything can be said to. -- BenRG (talk) 23:08, 9 September 2012 (UTC)
 * It depends, of course, on what you mean by "electron" and "space". Two electrons can occupy identical orbitals as long as they have orthogonal Spins, but you can still have exactly two electrons within the same "space" (if you take an orbital to be the space an electron occupies).  -- Jayron  32  23:19, 9 September 2012 (UTC)
 * Not necessarily. if an "orbital" "contains" electron(s) it must be X-times larger than any 1 electron, right?165.212.189.187 (talk) 13:35, 10 September 2012 (UTC)
 * The difference in thinking between an orbital "containing" and electron and an orbital "being" an electron are entirely moot, given that it doesn't really matter to the model what you believe about the "true" nature of the electron. The fact remains that electrons lack a definite location around the atom (see Uncertainty principle and particle in a box), that is it isn't just that we don't know where the electron is, it is that we cannot know where the electron is, so it isn't meaningful to speculate that it has a singular existance at any one point within the orbital.  The Pauli exclusion principle doesn't treat electrons as objects in motion around the nucleus, because it doesn't work that way.  If it did, you would have a non-zero chance of finding more than two electrons within an orbital.  Actually, you have a zero chance of finding them that way.  You get at most two, and only two, and only if their spins are orthogonal.  That's why the whole discussion about the "volume" of the electron becomes silly when you get to the more advanced models, the notion that an electron can be treated like a little ball just stops making sense.  -- Jayron  32  17:01, 10 September 2012 (UTC)
 * I don't believe so, if you consider the conservation of information then an orbital has different characteristics than an electron so how can two different "things" with different defining characteristics be the same?165.212.189.187 (talk) 15:45, 11 September 2012 (UTC)

See Degenerate matter for an example of electrons packed as tightly together as possible. When you add mass to a white dwarf it gets smaller because it is able to squeeze the electrons to higher energy levels and so therefore is able to put in more electrons per unit of volume. Hcobb (talk) 14:14, 10 September 2012 (UTC)
 * Apparently, our physical models predict that the energy density of an electron approaches infinity near the "centre" of the particle, if it indeed has any physical volume and mass, which is not possible to deduce beyond 10-18 metres. This, however, is probably a gross approximation. ~ AH1 (discuss!) 18:30, 11 September 2012 (UTC)

Physical inderpredation
From a Jackson textbook. The time averaged potential of a neutral hydrogen atom is $$V = \frac{q}{4\pi\epsilon_0}\frac{e^{-\alpha}}{r}\left(1+\frac{\alpha r}{2}\right)$$

where q is the magnitude of the electronic charge, $$\alpha^{-1} = a_0/2$$, $$a_0$$ being the Bohr radius.

It first asks to find the distribution of charge, both continuous and discrete. By Posson's equation you get $$\rho = -\epsilon_0\Delta V = -\frac{q}{8\pi}\alpha^3 e^{-\alpha r}$$. What does it mean by asking for discrete charge and is this even possible?

Next it asks for the physical interpretation of the result. What is it. Widener (talk) 19:22, 9 September 2012 (UTC)


 * Do you hab a gold? μηδείς (talk)
 * I beg your perdon? Widener (talk) 20:49, 9 September 2012 (UTC)
 * Jew zeeb do be of lou id inglizh zbeeger. Buds wrong bid your godson ends? Or are da ledders "dee" end "dee" negs do eadge udder on jour geeboard?μηδείς (talk) 21:06, 9 September 2012 (UTC)


 * discrete charge of nucleus and probability distribution of electron charge? (i'm guessing here, it's been a very long time)
 * This or this may help. Ssscienccce (talk) 21:45, 9 September 2012 (UTC)


 * Medeis, please see the second last paragraph. Bielle (talk) 22:00, 9 September 2012 (UTC)
 * Your point is that the header here is an honest misspelling, rather than deliberate? By a native English speaker with a spell-checking dialog box?  We disagree.  And your implying that my disagreement is in bad faith violates the very guideline do widge you boint. μηδείς (talk) 22:11, 9 September 2012 (UTC)
 * On what basis are you asserting that OP is a native English speaker? On what basis are you asserting that OP's browser is capable of spell-checking? On what basis are you asserting that OP deliberately misspelled?A8875 (talk) 00:02, 10 September 2012 (UTC)