Wikipedia talk:WikiProject Physics/Archive March 2010

Element books

WP:ELEMENTS started creating books on each individual elements. Since there are a lot of them, any help would be very much appreciated. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 02:32, 28 February 2010 (UTC)

Thanks for the tip, Headbomb. It is interesting that there are only 347 books at WP:books, according to the main page there. I thought there would be many more, because there are millions of registered accounts with Wikipedia. WP:Books is a really good idea (imho) Steve Quinn (formerly Ti-30X) (talk) 17:55, 1 March 2010 (UTC)

That page is greatly outdated. There are about 616 books in total as of now, 13 of which fall in our direct scope. (See also Category:Book-Class articles for a better category tree to browse).

Anyone interested in helping with books in general should join (or at least check out) WP:WBOOKS. There's a bunch of resources there. See WP:Books and Help:Books for more details (or just ask me, whichever). Headbomb {^ταλκ_{κοντριβς} – WP Physics} 19:26, 1 March 2010 (UTC)

Stub articles with physics banners

I changed a number of stub articles from "unknown importance" to "low", and that was my intention. But in the revision history I wrote the change was from NA to "low". I just don't want anyone to be alarmed that I inappropriately changed NA to "low". Only from "unknown importance" to "low". Hopefully this makes sense :) Steve Quinn (formerly Ti-30X) (talk) 04:46, 3 March 2010 (UTC)

Proposed Photo links

I've added or enhanced existing links to a handful of physicist pages; these links are to image search results at the Emilio Segrè Visual Archives. Pages include: Richard Feynman, Robert J. Van de Graaff, Ernest Lawrence, Wolfgang Pauli, and Harold Jeffreys. Please let me know whether there is a problem with this.

Sprout333 (talk) 18:38, 3 February 2010 (UTC)

I don't see why anyone would have a problem with this. You've fixed broken links and added ones to valuable pictures. So thanks a bunch! Headbomb {^ταλκ_{κοντριβς} – WP Physics} 06:05, 4 February 2010 (UTC)

What exactly do these links add to the articles? The images cannot be used on the project unless under a claim of fair use, as they are marked as copyright, and are also pretty small. I removed a bunch of them this morning as I was not aware of this discussion. What do others think should be done? --John (talk) 21:33, 24 February 2010 (UTC)

The links are valuable and come from a reputable source. Please replace them. 22:10, 24 February 2010 (UTC).— Preceding unsigned comment added by Xxanthippe (talk • contribs)

We dont use the images, we link to them on the copyright owner's website. Nothing wrong with that. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 22:41, 24 February 2010 (UTC)

I didn't say there was anything wrong with them; I was asking what they add to the articles. What do they add to the articles? --John (talk) 23:51, 24 February 2010 (UTC)

We feel that the links are valuable in that they connect users to primary source content not available on Wikipedia or Wikimedia itself. Isn't that what many external links in Wikipedia articles are there for? In our case, these are low-res photographs cataloged on our own site and freely available to anyone to use in educational projects, such as lectures, presentations, and non-commercial Web sites. If we had endless resources we might catalog our public domain images in Wikimedia (indeed, a few are there from other sources) as was done by the German Federal Archives (Deutsches Bundesarchiv); however, this is not the case. Most if not all of the links I added have since been removed. We're wondering whether it's worth our time to add anything further if only the same thing will happen again? Thanks for your consideration. Sprout333 (talk) 16:13, 1 March 2010 (UTC)

Why in the world were these reverted? These are wonderful links, to wonderful pictures?? Headbomb {^ταλκ_{κοντριβς} – WP Physics}

Wikipedia articles are not link collections. /Pieter Kuiper (talk) 16:45, 1 March 2010 (UTC)

No, but links to relevant things can nonetheless be present in articles. See the external links guide if you aren't familiar with it. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 16:59, 1 March 2010 (UTC)

I am familiar with the guideline and I am not sure I agree these photos add much value to the articles they were added to. I also have qualms about the site owners' motivations in posting the links; is it for us or for them? Certainly the owner or someone affiliated with them shouldn't ever be posting multiple links to their site to articles. If a consensus is reached here that the links are useful (something I am still not seeing), the links should be added by someone else. --John (talk) 17:28, 1 March 2010 (UTC)

Sprout333 came here looking for advice and complied with every WP:COI related advice that's out there. The Emilio Segrè archives benefit from exposure, and Wikipedia readers benefits from images they couldn't otherwise see. We should encourage these symbiotic relations between Wikipedia and every museum, archives, database and so on. If already have the image on the Wikimedia commons, then the Emilio Segrè archive links don't add anything. Otherwise we should keep them. These are pictures of very high historical value. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 17:44, 1 March 2010 (UTC)

I was not aware that Sprout333 works with the Segre archives, but this makes the links only more questionable. The Segre archives should make label their PD holdings as belonging to the Public Domain. They should also work harder to make authorship information available. /Pieter Kuiper (talk) 18:35, 1 March 2010 (UTC)

I do work for the the Emilio Segrè Visual Archives (ESVA); my apologies if this wasn't clear. As far as labeling public domain images goes, take a look at our Use Policy, specifically the information on credit lines. Many of these images are also, unfortunately, Orphan Works and we decided to make those images available rather than hide them away in our files. Our only goal here on Wikipedia is to make interested parties aware that usable images of notable scientists featured in Wikipedia articles are available on our site, which we feel to be authoritative. Many if not most of these images, including some public domain images, are not available on Wikimedia at this time. Sprout333 (talk) 20:55, 1 March 2010 (UTC)

An example: the ESVA Catalog #: Einstein Albert C29 says "date:unknown". Of course that cannot be true. It is a 1929 photo. It was published here. The photographer seems to be unknown, so this very nice photo must be in the public domain. /Pieter Kuiper (talk) 00:58, 2 March 2010 (UTC)

Thank you for the date information. Most of the info we have about the older images comes from the back of the prints. Of course, we add contextual info as we come across it, but the collection is not perfect. Sprout333 (talk) 17:41, 3 March 2010 (UTC)

Website hits are not a motivation - search engines alone generate far more hits for us than Wikipedia ever has. And financial gain is not a motivation - as our Use Policy says elsewhere, while we assess fees for high res reproductions to help cover the cost of preserving the collection according to archival standards and maintaining our online image database, we are very, very far from being a profit-making entity. We only want to see the images used, whether by a student who finds us via Wikipedia (or other websites) or a professional historian of science needing an image in an article. Thanks again for your consideration. Sprout333 (talk) 20:55, 1 March 2010 (UTC)

(unindent) Note that you could also upload the images on the Wikimedia Commons. I'll get someone from WP:OTRS to give you guidance on how to proceed. I'm not entirely sure how it works, but it's definitely something museums and archives have appreciated in the past. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 01:50, 2 March 2010 (UTC)

I'll be glad to help you. If you (Sprout333) can email permissions-en (at) wikimedia.org, attention Nihonjoe, I'll be able to work with you to get these images available to be used in the articles here. Please be sure to email from an email address at ESVA (it would be especially useful if you could email from one listed on the ESVA website so we can verify who you are). I'll be able to share more details via email. ···日本穣^? · 投稿 · Talk to Nihonjoe 06:50, 2 March 2010 (UTC)

It seems that the proposed links to ESVA are, for the most part, not welcome here and that cataloging individual images via Wikimedia is the preferred method. Thank you for the offers of help - we might consider uploading the public domain images to Wikimedia someday. However, that's a big, time-consuming project we can't take on just now as we are still scanning and cataloging our backlog (as well as receiving new donations all the time). If we do anything with Wikimedia in the near future, it would be in a limited way (as was my intention with the links) in order to to fill in missing gaps. The ESVA email is photos@aip.org, btw. Thanks for all of your ideas and feedback. Sprout333 (talk) 17:41, 3 March 2010 (UTC)

X-ray lithography

FYI, X-ray lithography is seriously messed up, and the current version is not an article but a message saying you should learn another language and read it off another language Wikipedia.

There was actual content on this page last year.

70.29.210.242 (talk) 11:54, 25 February 2010 (UTC)

I've reverted to an old version, but the article still needs looking at by someone who knows something about the subject. There seems to be some sort of a low-level editing dispute going on there, and this is just too far out of my field for me to want to get involved. Physchim62 (talk) 13:59, 25 February 2010 (UTC)

I might be able to take a look at this over the weekend. --Christopher Thomas (talk) 19:05, 25 February 2010 (UTC)

Update: I'm going to be busy for the next while, so I won't have an opportunity to look at this. --Christopher Thomas (talk) 00:08, 4 March 2010 (UTC)

New material at time dilation

A new editor (Howard Landman (talk · contribs) recently made this edit to Time dilation (edit | talk | history | protect | delete | links | watch | logs | views). This seems to be fringe material, and also seems to violate WP:COI (for the last of the added references). That said, I'd appreciate a second opinion or two before I revert/move it to the talk page. The editor seems to be acting in good faith. --Christopher Thomas (talk) 08:11, 1 March 2010 (UTC)

My first impression is that this is not "fringe", at least because the edit is very brief, explains it is not widely accepted, and does appears on the surface to have at least one notable citation. It is an interesting possibility. The appearance of self-promotion is something of a problem, especially as I can't tell whether that last reference is peer-reviewed or published in a reputable journal, etc. It does look like an interesting paper, but I would have to leave it to more experienced people to assess the validity of its contents. CosineKitty (talk) 20:11, 1 March 2010 (UTC)

Smells like COI from a far. As far as I can tell the papers by van Holten he is citing do not claim to propose a "new kind of time-dilation" but rather discuss effects of normal relativistic motion in strong magnetic fields. The claim of a "new kind of time-dilation" seems novel for Landman, who is not even a phycist (you check out his resume on the site hosting the paper). Since he apparently even cannot get his paper placed on the arxiv, I very much doubt that he has gotten it peer review. It definately should not be treated as a RS. TimothyRias (talk) 15:52, 2 March 2010 (UTC)

No comment on the content, but I agree with TimRias that it definitely doesn't meet WP:RS. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 17:04, 2 March 2010 (UTC)

In view of $E=\hbar \omega$ (see Matter wave#The de Broglie relations), it is reasonable to conclude that the rate at which one's time passes is proportional to the mass-energy of one's atoms (motion complicates things) which is why when one loses gravitational energy by moving closer to a massive body one experiences time dilation. Similarly, a charged particle near lots of opposite charges should experience time dilation. JRSpriggs (talk) 18:23, 2 March 2010 (UTC)

The time one experience as passing should be proportional to the Action (physics) one gets during that period. (That is, time flies when you are having fun (less action).) JRSpriggs (talk) 18:38, 2 March 2010 (UTC)

The problem is, the DeBroglie frequency doesn't seem to be related to time dilation in the relativistic sense (contrary to the claims of the last of the cited articles, though not necessarily to the others). Simple illustrative case: Consider a muon orbiting a hydrogen nucleus, and a muon orbiting a helium nucleus. One has a much shorter wavelength and much higher frequency of matter-wave oscillation than the other, but measuring the decay rate of populations of both of these exotic atoms will yield roughly the same half-life for the muon (the change in potential energy is small compared to the muon's rest mass). --Christopher Thomas (talk) 00:20, 4 March 2010 (UTC)

Adjusting for the mass of the particle and transforming from the co-moving frame to the observer's coordinates, one gets the rate at which time passes as ${\frac {E-{\vec {p}}\cdot {\vec {v}}}{mc^{2}}}\,.$ If one ignores potential energy, this becomes ${\sqrt {1-{\frac {v^{2}}{c^{2}}}}}\,$ as it should be. In your example, both E and p are larger for the fast moving muon near the helion, but the effects should mostly cancel in this equation. JRSpriggs (talk) 21:26, 4 March 2010 (UTC)

I agree -- but that is not what Mr. Landman's article is saying, unless I'm completely misreading it. It claims that the change in DeBroglie frequency is exactly equivalent to (relativistic) time dilation, which is not what you seem to be claiming. --Christopher Thomas (talk) 23:03, 4 March 2010 (UTC)

I was not addressing the disputed reference, but just discussing the substantial issue of whether there might be an electromagnetic time dilation. If we include electromagnetic effects (but ignore other forces), then ${\frac {E-{\vec {p}}\cdot {\vec {v}}}{mc^{2}}}={\sqrt {1-{\frac {v^{2}}{c^{2}}}}}+{\frac {1}{mc^{2}}}(e(\phi -{\vec {A}}\cdot {\vec {v}})+{\vec {P}}\cdot {\vec {E}}-{\vec {M}}\cdot {\vec {B}})\,$ where M is the magnetization associated with the particle's spin and P is the polarization which the magnetization generates when the particle moves. (I hope I got the signs right.) JRSpriggs (talk) 05:58, 5 March 2010 (UTC)

Perhaps I'm not seeing part of what you're getting at, but how is this different from any other SR-related time dilation due to motion? --Christopher Thomas (talk) 08:06, 5 March 2010 (UTC)

In the usual understanding of special relativity, the rate at which time passes is exactly ${\sqrt {1-{\frac {v^{2}}{c^{2}}}}}\,$ seconds of proper time per second of coordinate time without any "corrections" for potential energy. JRSpriggs (talk) 08:24, 5 March 2010 (UTC)

This may be a nomenclature issue, then, because I'd interpret the RHS as modifying the mass of the components of the system (and so slightly altering the velocities given conservation of momentum), leaving the ${\sqrt {1-v^{2}/c^{2}}}$ relation exact. --Christopher Thomas (talk) 18:19, 5 March 2010 (UTC)

(unindent) My intention when I derived ${\frac {E-{\vec {p}}\cdot {\vec {v}}}{mc^{2}}}\,$ was that mass was a constant typical of the type of particle but independent of the circumstances in which it finds itself (such as potentials or velocity). The idea was to calibrate the passage of time so that a muon would not be said to experience more time merely because it is more massive than an electron. So I "adjusted" ${\frac {E-{\vec {p}}\cdot {\vec {v}}}{\hbar }}=\omega -{\vec {k}}\cdot {\vec {v}}={\frac {d{\text{phase}}}{dt}}\,$ by dividing it by ${\frac {mc^{2}}{\hbar }}\,$ which is the value it would have when the particle is at rest in a vacuum in deep space so that all potentials are zero. In other words, the mass is used to calibrate the rate of passage of time so that it is 1 in a standard situation. JRSpriggs (talk) 02:56, 6 March 2010 (UTC)

I agree that this is a valid way of looking at it, but I question the idea that this would be the most conventional approach. My understanding was that a significant fraction of the rest energy of a particle came from its interactions with the fields associated with the types of charge it carries (apologies for phrasing this poorly). This makes an especially significant contribution to rest energy for particles carrying colour charge, but also occurs for interactions due to electric charge if I understand correctly. Viewed this way, changing the environment would certainly change the rest energy of the particles involved (in a way that always ensured that the system as a whole had the same total rest energy).

Is this a sensible way of viewing the situation, or am I off-base? This is outside my area of direct expertise. --Christopher Thomas (talk) 08:27, 6 March 2010 (UTC)

The rest mass of a charged particle includes the energy of it's field, but this contribution is hard to separate from other contributions, like different masses (Higgs interaction strength). This type of contribution only quantitatively gives the mass difference between the neutral and charged pion, and no other particles. You can see the magnitude of the effect for hadrons from the size of this difference, it's about 1% for hadrons, a little less, approximately equal to the ratio of strength of the forces.

For point particles, for electrons and quarks, the field contribution diverges like 1/cutoff for distances bigger than the Compton wavelength of the electron (the classical self-mass divergence), but only like log(cutoff) for distances shorter than the Compton wavelength (because antiparticle fluctuations have opposite charge). But divergent, so technically infinite, but they renormalize.

None of this has to do with the gibberish being put on the article: this stuff is not about the field contribution to the mass, it's about the effect of electric fields on general purpose clocks and rules. For neutral clocks and rules, there is no effect. The effect on charged clocks and rulers can be understood by reinterpreting the electromagnetism geometrically, as Kaluza Klein theory.

The only field that affects general purpose clocks and rules is gravitational, and this is well understood, supported by experiments. But since the expressions for momentum and energy involve the field, you can fake it out by expressing field independent quantities like "velocity" in terms of field dependent quantities like "canonical momentum", which makes it look like the rate of clocks depend on the field. They don't. Only on gravitational fields, not electromagnetic. This is all well understood for a million years.Likebox (talk) 19:52, 6 March 2010 (UTC)

Interactions which cannot be avoided in the standard situation (self-interactions and interactions with other parts of a composite particle) will be included in the mass, but those effects are always present and they do not change the fact that the mass is constant.

To Likebox: I did not see Landman mentioning macroscopic objects like rulers and clocks. He was talking about elementary particles and their decay rates.

It is not obvious to me on theoretical grounds whether electromagnetism should affect time dilation or not, in addition to the known effects due to gravity and motion. Only experiment can decide this. The question for Wikipedia is whether Landman's sources are reliable and whether he has a conflict of interest. Perhaps he might agree to allow us to copy the references from the paper he is writing rather than referencing his paper itself. JRSpriggs (talk) 17:51, 7 March 2010 (UTC)

Quantum physics demo

Could someone take a look at the Quantum physics demo article? It doesn't seem particularly suitable for the encyclopedia but I thought I would post here before suggesting it go to AfD. Thanks Smartse (talk) 23:06, 2 March 2010 (UTC)

The effect can be explained entirely on the basis of classical physics. The article is rubbish and should be deleted. Xxanthippe (talk) 23:13, 2 March 2010 (UTC).

Classical wave physics. The point is that it is difficult to understand in terms of photons, because if each photon is carrying a "property" and that property is unaltered by the polaroid, only selected, then inserting an extra polaroid cannot make more light come out. The example is first discussed in Dirac's "The Principles of Quantum Mechanics" Ch.1, but I agree that the article is lousy and should be deleted.Likebox (talk) 02:52, 3 March 2010 (UTC)

The title is wrong, the tone is wrong, and the explanation is full of mistakes. :-( --Steve (talk) 05:10, 3 March 2010 (UTC)

Another demonstration: I'm typing a message here, therefore I exist for a longer time scale than would be possible in a classical universe. Count Iblis (talk) 13:06, 3 March 2010 (UTC)

I have to agree that this does not appear to be an article that belongs in an encyclopedia. To wit: ...information cannot be included solely for being true or useful What_Wikipedia_is_not#Content and an article should not read like a "how-to" style manual, or advice column. WP:NOTGUIDE. There are suggested places for this type of article, whcih may be worth noting on the talk page of the article: How To Wiki or Wikibooks. ----Steve Quinn (formerly Ti-30X) (talk) 03:11, 5 March 2010 (UTC)

I missed one, see also: "wikiHow" ----Steve Quinn (formerly Ti-30X) (talk)

An alternative

I hereby nominate both Headbomb and Likebox for the position of co-Grand Poobah. This situation is already pretty ridiculous, why not dive into full absurdity? The Wordsmith^Communicate 03:58, 24 February 2010 (UTC)

Support

1. as proposer. The Wordsmith^Communicate 03:58, 24 February 2010 (UTC)
2. per The Wordsmith, although I want a silly hat and royalties of 1 Zimbabwean dollar per use of the letter "e" on wikipedia. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 04:45, 24 February 2010 (UTC)

   (comment) A hat like this one? --Christopher Thomas (talk) 06:48, 24 February 2010 (UTC)

3. Fantastic! Support.Likebox (talk) 06:04, 24 February 2010 (UTC)
4. Push this resolution through and end the matter. ScienceApologist (talk) 16:11, 24 February 2010 (UTC)
5. Only if the hat is required! --Falcorian ^(talk) 18:27, 24 February 2010 (UTC)
6. Hear, hear. Scog (talk) 15:13, 2 March 2010 (UTC)

Oppose

1. I'm sorry, but there's no way that I can support the appointment of the co-Grand Poobahs of WikiProject Physics until the design of the silly hat has been settled. I would favour something with lots of fuzziness, to represent the inherent uncertainty of most things in physics and everything on Wikipedia. The general design should be based on Feynman diagrams, to reflect the strong particle physics community within the project: this one seems like a good bet... Oh, and there should be lots of flashing lights to symbolize the importance of macroscopic electromagnetism in all our work: after all, where would Wikipedia be without macroscopic semi-classical electromagnetism? I think the Silly Hat Problem is fundamental, as the co-Grand Poobahs will obviously only be able to exercise the privileges of the office (of which there shall be none) whilst actually wearing the silly hat, and so to establish the office without designing the silly hat would simply be inviting them to take advantage of something they won't have anyway. After all, we will certainly have the spearhead battalions of the relativistic army complaining (almost) instantly that the wearing of the silly hat was not simultaneous with the non-exercise of the non-existent privileges, at least, not in their frame of reference! But possibly we could take advantage of some nifty quantum phenomena to allow the silly hat to be reasonably close to all our heads, at least while editing this page, and so to allow all of us to be Grand Poobahs... Physchim62 (talk) 23:41, 24 February 2010 (UTC)

   I want one such hat, too! ― A._di_M. (formerly Army1987) 21:29, 8 March 2010 (UTC)

Sigh. Schrodinger equation

An editor here, named headbomb, has decided to take it upon himself to purge the long-standing use of natural units in some of the sections of the article Schrodinger equation. He did so incorrectly, and these were not typos--- he consistently put in the wrong power of hbar in every equation he modified, and there were many. I will ask other editors if they could talk reason into him.Likebox (talk) 23:06, 27 February 2010 (UTC)

A more accurate description of the situation would be that there is consensus to not use natural units. I'm now implementing that consensus (and made some mistakes, forgetting to square hbars mostly), infuriating Likebox that he didn't get his way. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 23:18, 27 February 2010 (UTC)

The correct way to characterize this is that there is a discussion underway to determine how much to use natural units. Me and Count Iblis are in favor of "as much natural units as possible", Headbomb would like "no natural units at all", while Bduke would like elementary articles to have explicit hbars, and advanced articles to not have them. CosineKitty is currently weighing the issues (as a non-expert editor) and we are all trying to persuade people. Consensus has not developed yet.

The issue I have that the edits headbomb made to insert c's and hbar's were completely incompetent: He wrote E^2-p^2 = m^2c^4! He wrote wrong powers of hbar everywhere, and forgot to replace hbars where they are necessary. This type of careless editing borders on vandalism--- mathematical text is very fragile.Likebox (talk) 23:21, 27 February 2010 (UTC)

I would also like editors to consider that some editors spent a lot of time and effort getting articles correctly written, and do not want their text littered and "improved" by insertions of useless physical constants. I suggest the following convention:

For intermediate steps in a mathematical derivation, use whatever units are clearer. For equations which are likely to be used to compare to experimental data, use engineering units.

I hope this satisfies everyone.Likebox (talk) 23:35, 27 February 2010 (UTC)

No, it is completely ridiculous to work in natural units on Wikipedia, especially on articles which could be accessible to undergrads were it not for the choice of natural units. We write for readers, not for us. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 23:43, 27 February 2010 (UTC)

Natural units are accessible to undergrads, and they are the universal convention for mathematical derivations in the field. I ask that you stop inserting incompetent hbars and c's. The page is a mess.Likebox (talk) 23:49, 27 February 2010 (UTC)

No they aren't! Pick any undergrad books on the topic, and they all have the hbars and the cs. Take Shankar's Principles of Quantum Mechanics which is an excellent textbook on the topic, both for undergrads and grads, or Eisberg and Resnicks' Quantum Physics of Atoms, Molecules, Solids, Nuclei, and Particles (undergrad level) for examples. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 23:53, 27 February 2010 (UTC)

Natural units are the accepted standard for all relativistic quantum mechanics at least. For nonrelativistic quantum mechanics, there is only one constant, hbar, so there is less benefit to natural units (although there is some). I ask that editors who did not edit mathematical text do not go around "improving" it with nonsense constants.Likebox (talk) 00:00, 28 February 2010 (UTC)

Well, I'm looking at Greiner's Relativistic Quantum Mechanics (part of a series of texts) and it has all the h-bars and c's. Of course, mostly because he's a quantum physicist, not a GR guy. I tend to like this stuff left in. It's the general relativists who started the no-c-disease, arguing that you can always put the units back in at the end, if your stoichiometry is off. AS IF they themselves never made any dumb math errors that they caught later by NOTICING that not all terms of a equation had the same units, and the exponentiated terms weren't unitless, etc. You can use the stoichiometry to fix your math mistakes, OR to restore the constants you left out, but it's very hard to do BOTH. As for the QFT people, they cheat by using alphas when they can :). Could I suggest a compromise that in general our articles (at least the undergrad ones) leave them all in, and only take them out after presenting some version where they're present? SBHarris 01:12, 28 February 2010 (UTC)

It is good that the question has come here and I hope that others will comment. I do not know where Likebox gets "CosineKitty is currently weighing the issues (as a non-expert editor)". That user has not said that. Likebox is mind reading. His "Natural units are accessible to undergrads" is not addressing the undergrads I meet. "Bduke would like elementary articles to have explicit hbars, and advanced articles to not have them" is not my position. My position is that articles such as Schrodinger equation that attract a readership from many disciplines as most more elementary topics would, should use hbar throughout. Advanced articles might use natural units in the more advanced part of the article, but should have a clear and simple introduction that does not use natural units. I made that clear several times. I have recently added a comment to Talk:Schrodinger equation suggesting that there is not even consensus on which natural units to use. All chemists use atomic units at graduate level and these are different to the ones in the article. --Bduke (Discussion) 00:07, 28 February 2010 (UTC)

In general we should use SI units so that experimental physicists and engineers (and ordinary people) can understand the equations. It is OK to also show the equation in natural units, saying something like "theoretical physicists often work with natural units in which the equation takes this form". JRSpriggs (talk) 01:16, 28 February 2010 (UTC)

So what you are all saying is that:-

1 we can use Hbar or natural units.

2 If we use natural units there are more than one of them and so the equation has to be repated again and again to explain each of those natural units ?

3 If we use hbar we dont have to have all those repetitions but we end up with "messy" calculations

4 Hbar is the standard for up to degree level and after postgrad it is natural units (as per the particular field of the person calculating)

Would you all agree that the percentage of readers of each level would probably be Layman = Majority, Grad level = Minority and Postgrad = V small minority  ?

If that is true I say we use hbar. Even for me the calculations without hbar are more easily understood - but if they are not easily understood by undergrad and below and there is a possibility of misinterpretation due to "the natural unit used" then it seems clear to me to use hbar until such time as it is dropped from the majority of text books at all levels. If No3 is also correct then it is better to have a couple of meesy looking equations than lots of repetitions of them for each natural unit

Chaosdruid (talk) 01:19, 28 February 2010 (UTC)

Since there have been many reversions, can we have one good diff between two versions that are good examples of what the two sides want to see (modulo possible incorrect powers of hbar)? My teaching experience tells me that many students have to re-learn a bit about units at university to get the most out of Natural units. While Likebox is correct in principle (that things are easier when using natural units, that putting these constants back is trivial etc. etc.) most people don't know how to do that efficiently without some practice. In general, I would suggest that we use natural units for relativistic stuff. E.g. the article on special relativity doesn't do that and you can see that the expressions for the Lorentz transform matrix and the metric tensor become quite complicated. You really do not want conversion factors of c inside tensors and four-vectors.

We should also note that, paradoxically, Natural units (interpreted as dimensionless units, some people call that geometrized units) are often more powerful to do dimensional analysis in than in cgs or SI system (particularly in quantum mechanics or relativity). When we do dimensional analysis, we actually study some scaling limit. Nonrelativistic physics corresponds to zooming in into phenomena that evolve on long time scales and then taking that zoom factor (c) to be infinite. But then we might just as well do that straight away starting from Natural units. Computationally, it is most efficient to mix up Si and Natural units so as not to have to derive relations that everyone already knows. Example,

E.g., let's derive the ground state energy of the Hydrogen atom up to a constant. You can do that by writing down E = m, then reinsert c to get E = m c^2. But now the scaling limit c to infinity does not exist anymore, so we put in a factor alpha^2 because alpha contains a factor 1/c, and end up with E = alpha^2 m c^2. The fact that alpha being dimensionless means that other factors in alpha should change in SI units if you change c is irrelevant here, as we are not keeping numerical values the same under rescaling. What matters is that we end up with a formula that when interpreted in SI units is correct and it is a non-relativistic formula that doesn't contain c if you write it out in terms of the electron charge, hbar, m etc. Count Iblis (talk) 01:24, 28 February 2010 (UTC)

Agree with SBHarris. People usually learn QM natural units after learning a substantial amount of QM, not before or during. That's the way it should be, and that's the way it is in almost all courses and textbooks. Therefore, articles on basic aspects of QM (like the Schrodinger equation) should generally not use them, or occasionally put in both forms (with explanation and link) when it helps make a pedagogical point. :-) --Steve (talk) 04:35, 28 February 2010 (UTC)

When writing quantum mechanics, one must set hbar to 1 for good comprehensibility and readability. As I said on the article talk page: writing hbars is like a stutter, it is a mark of incompetent mathematical writing. Whether you also want to set c to 1 (natural units), or the mass of the electron to 1 (atomic units) or go further and set G=1 (Planck units) is irrelevant, hbar just has to be 1, that's it.

You cannot use hbar to "check that the units match" in any useful way. What happens if you don't set hbar to 1 is that you end up defining two sets of objects--- energy and frequency, momentum and wavenumber, which are identical except for units, and are proportional with a factor of hbar. This duplication of symbols causes much more confusion for students than saying "I am using units where hbar is 1".

In quantum mechanics there is no distinction between energy and frequency, between momentum and wavenumber. The only thing that hbar lets you do is check the unit conversion on your duplicated symbols. It is of absolutely no help in checking the correctness of the nontrivial part of any calculation.

About setting c to 1 in relativity:

If I were to choose to use "inches" as a unit of height z, and "cm" as a unit of length x and width y, then the Laplace equation would read:

$\partial _{x}^{2}+\partial _{y}^{2}+{1 \over k^{2}}\partial _{z}^{2}$

where k is a constant with dimensions cm/inch, with the value

$k=2.54{cm \over inch}$

We don't do this, because we find rotational invariance intuitive enough that we just "know" that height and length and width are really fundamentally the same and should be measured with the same units. In relativity we discover that rotational invariance includes time, and that we stupidly chose bad units so that there is a mismatch between the unit of time and the unit of space. There is a conversion factor c, which is the speed of light, which incessantly converts units. It is always a bad idea to include factors of c in articles about relativistic systems: it is as ridiculous as including factors of "k" when converting length to height.

The problems only get worse as the article gets more advanced: The Hawking temperature formula can be derived in a few lines from the imaginary time periodicity of the Schwartschild solution (in natural units). The answer is:

$T_{H}={1 \over 8\pi M}$

But if you insist on engineering units, this is:

$k_{b}T_{H}={1 \over 4\pi }{\hbar c \over {2GM \over c^{2}}}$

Further, by using combinations of G,hbar, and c, and defining quantities like "R_s = 2GM\over c^2", you essentially end up giving up to 6 different names for the same quantity. This multiplicity is distracting from the content--- and it is all trivialities.

I don't understand how editors who do not write mathematical text can be so adamament that this is the way you write it. Please do not vandalize good contributions by littering them with constants.Likebox (talk) 05:33, 28 February 2010 (UTC)

A good faith attempt to improve the encyclopaedia is not WP:VANDALISM, and accusing other editors of such just because you disagree with them is not going to win them over, and long term will only lead to your own conduct being called into question.

On the broader question you are simply wrong on natural units. I will use them when doing relativistic mathematics, but I do not for one second think that e.g. $E=m$ is preferable to $E=Mc^{2}$ in general contexts. The latter contains useful information that helps a reader understand mass-energy equivalence. The former doesn't. The equivalent constant here is hbar, and the formulae are much clearer with it.--JohnBlackburne^words_deeds 06:33, 28 February 2010 (UTC)

(deindent) But inserting incorrect factors of hbar, and reverting a user who removes these incorrect factors is vandalism under any definition.

You are wrong about the meaning of E=mc^2 (it just means E=m) you are wrong about the use of hbar. I pity you. It is too bad that the people who actually write the material are second guessed by the people who don't.Likebox (talk) 07:35, 28 February 2010 (UTC)

I actually think that nobody who wants to put in the hbars will be able to correctly do it. The page is more advanced than you think, and some of it doesn't appear in elementary textbooks. Some of it is actually an introduction to supersymmetry methods (but it doesn't look like it). It was written with much care, and now it is being vandalized with much glee.Likebox (talk) 07:44, 28 February 2010 (UTC)

If this is the case, then the general references that exists at present is not sufficient. It is time you put in some specific inline references. But it could just be that you are taking the subject further than it needs to go in this article. Maybe material should be moved to another article or just deleted. We do not put everything in, particularly if it is only supported by primary sources or original research. --Bduke (Discussion) 09:33, 28 February 2010 (UTC)

Yeah yeah we get it, we're all stupid clueless vandals who couldn't pass physics 101 if had Steven Weinberg next to us telling us the answers. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 07:49, 28 February 2010 (UTC)

Stop putting words in my mouth: I was saying that there are parts of the article, the propagators and the superpotential parts, where putting in the hbars is both an incredible pain, and an incredible distraction. I don't care at all about the people here, so long as they write actual material instead of reducing the quality of the little mathematical material that there is.Likebox (talk) 07:55, 28 February 2010 (UTC)

I did not put any words in your mouth. I'll quote I actually think that nobody who wants to put in the hbars will be able to correctly do it = we're all stupid. It was written with much care, and now it is being vandalized with much glee. = we're a bunch of vandals (me in particular). Headbomb {^ταλκ_{κοντριβς} – WP Physics} 07:57, 28 February 2010 (UTC)

STOP PUTTING WORDS IN MY MOUTH: the words in green are mine: the words to the right of the equal sign are not what the words I said mean. I got news for you: you only put hbars in the easy half of the article, and only in the places where it isn't the worst distraction. I can live with that. You certainly didn't do it in the entire article (although if you think you did, thank heavens).

You don't write mathematics, you go in and make other people's mathematics hard to follow. Thank you for your continued contributions.Likebox (talk) 08:06, 28 February 2010 (UTC)

I'm fully aware that I did not cover everyting. See Implementation, where I detail what I missed and ask for other people's help. Since it most likely won't be you, maybe others from this project will raise up to the occasion. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 08:13, 28 February 2010 (UTC)

You should not edit physics articles, none, under any circumstances. Your understanding of the content of the articles is very limited.Likebox (talk) 08:37, 28 February 2010 (UTC)

Where did I say "meaning"? Please read WP:VANDALISM especially WP:NOTVAND. And if you see a mistake in a good faith attempt to improve the encyclopaedia that is fixable the correct action is to fix it, not revert it against consensus.--JohnBlackburne^words_deeds 07:52, 28 February 2010 (UTC)

What I'm telling you is that this "consensus" is absurd: any one person, with time, will come to see that writing mathematical manipulations while toting hbars around is impossibly inconvenient. Unfortunately, it takes experience, the explanation of this is intricate, and it has to be repeated for each editor, and it's the traditional Wikipedia Whack-a-mole. For every three you convince, with great effort, four more show up. The current way headbomb did it, where all the parts that people recognize have hbars is not horrible. The only parts that are horrible were the lattice approximation and the relativistic equation, and I fixed those.

As for telling me to fix wrong factors of hbar in mathematical prose that I wrote specifically to be in natural units: that's what people I grew up with would call chutzpah.Likebox (talk) 08:01, 28 February 2010 (UTC)

Now, no-one owns the text, so that you wrote it one way does not mean you have a special veto on it being changed in line consensus. And on consensus, as you seem to understand it, and have acknowledged it is a against you, perhaps it's time to deal with it rather than keep failing to persuade us we are wrong (which you're not trying to do anyway - that you wrote it originally or that it's "inconvenient" to you are not even arguments).--JohnBlackburne^words_deeds 08:35, 28 February 2010 (UTC)

(deindent) I didn't claim I "own" it! I claimed that I am familiar with it, and so I know exactly what a destructive thing it will be to change it from natural units. If you look at the first half of the article, peace of cake. But in the second half, if you look at stuff in there, if you start littering the hbars, you just can't do the boosts properly, nor the superpotential stuff, nor the propagator, not anything. It's all wrong units for that, and it's all done in natural units in the professional literature. I wouldn't know where to put all the hbars, or how. There's no convention, because all this stuff has been done in natural units forever.

The problem is that you are making rash judgements without actually looking at the text in the article. Headbomb is adding hbars without checking for consistency from one equation to the next, and revealing appalling gaps in his understanding of dimensional analysis. Everybody here is talking out of their asses without reading the actual text and thinking about what it means to use SI units, and I'm the only one that has the whole text in my head, so I know how ridiculous what you are saying is.Likebox (talk) 08:43, 28 February 2010 (UTC)

tl;dr, but I think it depends on what you're doing. There's nothing wrong on using c and ħ in introductory articles, and sometimes it even makes it easier to "see" how the classical limit is approached as c → ∞ and ħ → 0, but using them in advanced theoretical articles about stuff with no classical analogue, e.g. in Clebsch–Gordan coefficients, is just plain silly (and I don't think it'd occur to anyone to do that in the first place). Personally, I'd not use them in Spin–orbit interaction, but it has happened to me to be told off for "forgetting" about powers of ħ and c in the expression for it during an exam. (When that happened, I just wrote those factors down without making a fuss.) ― A._di_M. (formerly Army1987) 21:25, 8 March 2010 (UTC)

Discrete S.E

Now headbomb insists on putting absurd hbars on lattice approximations! This takes the cake. I don't know if anyone here knows what a lattice Schrodinger operator is like, but to put an "hbar" on it is like putting units of "meters" on the lattice in lattice QCD. It's ridiculous. Headbomb just puts "hbar^2" in front of every object he sees.

This editing with lack of understanding is extremely disturbing, and it is a recurring pattern.Likebox (talk) 08:15, 28 February 2010 (UTC)

The article is not written in natural units by consensus of everyone. Live with it. If you don't like hbars, do the substitution hbar = 1 in your head. All other people will wonder "Hey, what the hell happened to the hbars?" if they aren't present. So unless hbar^2 is factually wrong rather than midly annoying to those who are used to see it in natural units, stop climbing the Reichstag. The same applies below to the Klein–Gordon equation. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 08:21, 28 February 2010 (UTC)

You don't understand: these hbars are simply wrong in every interpretation. This is not a units issue--- it's a meaning issue. hbar on a lattice approximation doesn't mean anything.Likebox (talk) 08:26, 28 February 2010 (UTC)

Reference? Headbomb {^ταλκ_{κοντριβς} – WP Physics} 08:28, 28 February 2010 (UTC)

One reference is the Feynman Lectures on Physics, Vol III, the lattice Schrodinger equation as a hopping model. You are editing with no comprehension--- like a blind bull in a china shop.Likebox (talk) 08:30, 28 February 2010 (UTC)

Chapter/Page? Headbomb {^ταλκ_{κοντριβς} – WP Physics} 08:33, 28 February 2010 (UTC)

Go find it yourself--- it's a short book.Likebox (talk) 08:44, 28 February 2010 (UTC)

I know, since I own it. I looked at the TOC, the index, went through the book quickly, and saw nothing that talks of anything remotely close. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 08:51, 28 February 2010 (UTC)

Look at the part where he has a tight binding model--- the electrons hop from atom to atom, so that the wavefunction spreads out. He has a hamiltonian matrix which links nearest neighbor atoms and a list of differential equations for the "C_i". It's the discrete Schrodinger equation Hamiltonian. If you've read the book you couldn't miss it. I don't own it anymore.Likebox (talk) 08:53, 28 February 2010 (UTC)

Yes, and these equations are full of hbars too. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 08:58, 28 February 2010 (UTC)

Full of hbars in time, not in space. The space parts have no hbar, and this is what you are inserting blindly.Likebox (talk) 09:11, 28 February 2010 (UTC)

As I said--- this is not about natural units. This is just about wrong stuff that you insert with such confidence!Likebox (talk) 09:12, 28 February 2010 (UTC)

Relativistic Klein Gordon Eqn.

For Klein Gordon equation, unlike S.E., there is a massive consensus on natural units in the literature. Headbomb also insists on reverting these. I would like a large number of people to stop this.

(Headbomb: you don't understand what you are doing here--- you are ending physics on Wikipedia. Perhaps it was inevitable.)Likebox (talk) 08:15, 28 February 2010 (UTC)

See above.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 08:21, 28 February 2010 (UTC)

The above concerns the Schrodinger equation, not the Klein Gordon equation, where there are two constants, c and hbar, and so twice the confusion--- you must stop doing this, it is mathematical vandalism.Likebox (talk) 08:27, 28 February 2010 (UTC)

But you can actually write about that in the article itself and then motivate natural units that way. I just added in a sentence about that in the article. What we can also say is that just like c pops up everywhere in relativity and is nothing more than a conversion constant, e.g. between mass and energy, now hbar appears playing a role of nothing more than another conversion constant. There is nothing wrong mentioning this in the article itself and then writing down the same KG equation again without hbar and c. The point that should get across to readers is that the physics is mass = energy = inverse length, the hbars and the c's are the trivial unit conversion constant if you decide to measure mass, energy and inverse length in incompatible units within the same equations. Count Iblis (talk) 14:04, 28 February 2010 (UTC)

I agree that units aren't that useful in that equation, but the cost of using them is minimal: just say that $\square ={\frac {1}{c^{2}}}{\frac {\partial ^{2}}{\partial t^{2}}}-\nabla ^{2}$, $\mu {\stackrel {\scriptstyle \mathrm {def} }{=}}{\frac {mc}{\hbar }}$ and then you don't need to use ħ or c any more. —Preceding unsigned comment added by A. di M. (talk • contribs) 21:12, 8 March 2010 (UTC)

Likebox again... sigh

Apologies to those getting tired of this sort of thing (which should be just about everyone, me included), but Likebox is currently soapboxing/venting his rage on Wikipedia:WikiProject Physics/Participants. Personally I'd remove the entire message (or move it on the talk page) since he's moved on to Citizendium anyway (see [1]), but since I'm involved and I don't want to create more shit than we're currently dealing with, I'd rather that someone uninvolved would do it.

I can't wait for this project to get back to its happy normal state. I'm so tired of this crap. Headbomb {talk / contribs / physics / books} 09:12, 8 March 2010 (UTC)

I reverted his last addition. Fine for his talk page or user page, even here where it could be ignored, but not a project page. As for his message as it stands if he's leaving then it serves no purpose, as apart from stating the obvious the links to his own pages make no sense if he's not here anymore.--JohnBlackburne^words_deeds 17:49, 8 March 2010 (UTC)

Observer-centered formalism

This article was created today, there are no Google hits for this term. Is it a recognised theory? Cassandra 73 (talk) 18:18, 8 March 2010 (UTC)

No. Sent to deletion. Headbomb {talk / contribs / physics / books} 18:36, 8 March 2010 (UTC)

Talk:Black hole

We've had two extended threads at Talk:Black hole about peoples' pet theories about black holes so far this year. What do people think about putting a variant of Talk:Big Bang's "IMPORTANT: please don't post about your pet theory here" notice over there, to hopefully forestall future extended threads?

Disclaimer: I've been involved in some of these threads, and arguably helped some of them drag on longer than they should have.

If people think this is a potentially useful thing to do, I'll start up a straw poll at Talk:Black hole to confirm that there's community support, and to ask for useful form links to direct people to for posting original work. --Christopher Thomas (talk) 20:40, 8 March 2010 (UTC)

I think it is a good idea. There are comparable notices on Talk:Earth about Mostly Harmless as well as the lack of coverage concerning young Earth creationism. It seems to cut down on the noise a little. Some talk pages have notices about recurring themes. The Talk:Evolution page has a FAQ that includes past discussions.—RJH (talk) 19:28, 10 March 2010 (UTC)

Same, it can't hurt. Headbomb {talk / contribs / physics / books} 22:16, 10 March 2010 (UTC)

The straw poll is up at Talk:Black hole#Straw poll: talk page notice. Please post opinions (positive and negative) and comments/suggestions there. If this turns out to be overkill, I'd rather know about it before putting the notice up. Likewise if there's a better way to word the notice. --Christopher Thomas (talk) 22:54, 10 March 2010 (UTC)

Zero-energy Universe

An IP editor (90.229.235.204 (talk)) created this article and has been adding links to it to multiple cosmology-related articles. I won't be in a position to clean this up for a few hours; would someone else be willing to take a look at it, and if necessary have (polite) words with the IP user? --Christopher Thomas (talk) 18:35, 11 March 2010 (UTC)

I've heard that idea before, but I don't remember whether it was intended as wild speculation or there was a meaningful reason for the speaker/writer to believe it. ― A._di_M. (formerly Army1987) 20:04, 11 March 2010 (UTC)

Originally coined by a real physicist (Tyron?) speculating about the universe being a quantum fluctuation. Boosted into mainstream by "free-lunch" inflation. --Michael C. Price ^talk 20:47, 11 March 2010 (UTC)

Would it be better to merge the new stub into an appropriate article? --Christopher Thomas (talk) 22:16, 11 March 2010 (UTC)

I tried to create a similar section in inflation years ago but it got squelched, and I'm sure it would again. A separate article is probably best. --Michael C. Price ^talk 00:26, 12 March 2010 (UTC)

Physics (disambiguation)

I am thinking it would be worthwhile to link the other physics pages to this disambiguation page. I have linked a number of them already. I will continue to do so, over time. It will take awhile to finish including with bullet summaries. If this doesn't work for the physics community then just let me know. ----Steve Quinn (formerly Ti-30X) (talk) 15:20, 12 March 2010 (UTC)

There is an Index of physics articles page, so maybe a lengthly disambiguation page is redundant. Also, the main article "Physics" has linked summations to articles about "Core theories of physics", "Research fields" in the physics arena, along with "Applied physics", and even "Unsolved problems in phyics" article, etc. etc. In other words, there is a plethora of wiki-linking to the subdisciplines and articles of physics from this one page ("Physics"). Perhaps, the disambiguation page should contain only a selection of represenative articles. Any suggestions? --Steve Quinn (formerly Ti-30X) (talk) 16:02, 12 March 2010 (UTC)

Er, there is really no need to include articles like Mathematical physics - someone typing physics into a search bar is not looking for that article. Helping people find the information they want is great, but if they are looking for a particular sub-discipline and do not know its name, there are categories and really quite nice navboxes at the bottom of Physics. - 2/0 (cont.) 21:32, 12 March 2010 (UTC)

Quantum gravity

A new editor added a reference link to this article from what appears to be a fringe author, which I removed (with comment). They've now added it back in. Could someone else take a look at this to see whether or not I'm off-base? --Christopher Thomas (talk) 18:10, 12 March 2010 (UTC)

Isotope and nuclide merge proposal

Following the example of stable nuclide, I think it's time to modernize both the the isotope and nuclide articles, by merging them. Best current suggestion, to avoid people going to one page when they want the other, is to merge them to only one article, entitled Isotope and nuclide and have both isotope and nuclide redirect to it. That article will explain the (modern) difference in terms in the lead/lede (isotopes refer to the group of nuclides of a single chemical element only), then launch into a history section of isotope discovery, moving onto the history of the term nuclide (hopefully). Then the rest of the modern stuff follows. Since "isotope" and "nuclide" were once synonyms, with isotope being used once as we now use the word "nuclide" (which didn't exist), discussing them in the same merged article seems the best approach.

This is mostly a chemistry topic (see the talk:isotope page, and please comment there, not here), but it has been suggested that due to the nuclear physics component from nuclide, that the proposed merge be announced here, also. SBHarris 23:06, 12 March 2010 (UTC)

Impulse

FYI, Impulse was moved to Mechanical impulse without discussion, there is now a request to move Impulse (disambiguation) to Impulse. See Talk:Impulse (disambiguation)

70.29.210.242 (talk) 05:09, 13 March 2010 (UTC)

Unit commensurability

The new article titled unit commensurability needs work, including;

• Other articles linking to it;
• Citing sources in the literature;
• Expansion of the article.

Work on it. Michael Hardy (talk) 19:02, 13 March 2010 (UTC)

I don't think it can ever be anything but a dicdef, and it's a pretty dubious one at that. I've nominated it for deletion. --Trovatore (talk) 20:52, 13 March 2010 (UTC)

WildBot and FrescoBot

Recently, this tag-team pair of robots has been working on some of the physics articles. User:FrescoBot seems to be combing articles looking for broken section links and links that need disambiguation, and if it finds them, flags the articles for attention by the second robot. User:WildBot puts a couple of big templates on the articles' talk pages describing the problems it found and linking to an external tool that attempts to help fix them. The two robots are maintained by different users (WildBot was originally supposed to be manually summonned, I think).

I'm not convinced that the robots' attention is a good thing. My main complaint is that it's cluttering up the talk pages, which already have a mile-long list of templates. On the other hand, it's not necessarily a bad thing, either; it's just making a small mess. I've been sticking {{cot|Click to show link-fixing robot's report.}} ... {{cob}} around the templates, as a least-damage interim measure, and have pinged WildBot's maintainer (politely) to ask about doing something similar directly.

Partly I'm posting to give everyone else a heads-up before FrescoBot finds articles you help maintain, and partly to see if anyone else has thoughts about what, if anything, should be done in response to this series of events. I'm of two minds, per above. --Christopher Thomas (talk) 17:36, 17 March 2010 (UTC)

I have seen this happen. I fixed the broken links so tagged in two articles. After that, WildBot removed the template so that if you did not look at the history of the talk page you would never know that anything had happened. So there is no problem. JRSpriggs (talk) 17:57, 17 March 2010 (UTC)

Perhaps it's just me being cynical, but I suspect the natural state of articles is "broken". Which means the templates will be present a not-insignificant amount of time. Having this be less obtrusive would IMO be a plus, as right now they're the first thing a visitor to the talk page sees (rather than the "skip-to-toc" link, any notices people have put up, or what-have-you). --Christopher Thomas (talk) 18:14, 17 March 2010 (UTC)

Template clutter is an eternal problem as it tends to drown out the signal in all the noise. I'm not sure what the best solution is there, although template consolidation can help. I have found Wildbot to be helpful when I'm putting together a new article.—RJH (talk) 18:50, 17 March 2010 (UTC)

I found it amusing that a bot had "summoned" another. But I hadn't noticed the tag itself until now. Yes, it's a tad obtrusive IMO, but if it were below {{skiptotoc}} I'd not think it's a problem. ― A._di_M. (formerly Army1987) 19:52, 17 March 2010 (UTC)

If it were at the bottom of the template list, I wouldn't have bothered wrapping it either. My main concern is with all of the "don't post your own theories here" and "go here to ask questions" templates at places like Talk:General relativity, Talk:Big Bang, and Talk:Black hole. The average user will only read the first or maybe second template before getting bored, so high-importance templates for inexperienced users should IMO come first. The WildBot templates are the exact opposite of this - low-urgency maintenance templates useful mostly to experienced editors. In an ideal world, the information would be put in a conversation thread rather than be in a head-of-page template at all (but bots aren't quite that sophisticated yet).

I realize that views on this type of talk-page feng shui will vary. This is just my own take on the matter. --Christopher Thomas (talk) 20:01, 17 March 2010 (UTC)

So far I have been able to fix all the broken links it pointed out (in articles on my watch list) except for one section link for which no appropriate target existed (which I changed to a red-link) and a disambiguation needed (it did not provide enough information to find the link). JRSpriggs (talk) 19:51, 17 March 2010 (UTC)

Thanks. The repair-tool was interacting badly with my (ancient) browser. --Christopher Thomas (talk) 20:01, 17 March 2010 (UTC)

FrescoBot tagging switched off

The creator of User:FrescoBot has for the time being switched off the WildBot-calling feature of that bot, in response to complaints from other WikiProjects. If automatic tagging of WP:PHYS articles is a feature people think would be useful, by all means suggest mutually-acceptable workarounds at User talk:Basilicofresco (it's not my area of expertise). --Christopher Thomas (talk) 00:23, 18 March 2010 (UTC)

Update: The author of WildBot has agreed to modify it so that its templates are added at the end of the list of templates on the page, rather than at the beginning. This removes my objections to automated tagging of physics articles. --Christopher Thomas (talk) 04:10, 18 March 2010 (UTC)

Book clean up

WildBot was mentionned above, so I thought I would mention this here while it's relevant. WildBot doesn't only go through articles, it also goes through books and create a problem report on the talk page (with details on the cause and effects of these problems, and what to do to fix them). There are currently 6 physics-related books that needs cleanup.

• Book:Energy (problems)
• Book:Hamiltonian Mechanics and Mathematics (problems)
• Book:Hydrogen (problems)
• Book:Matter (problems)
• Book:Physics (problems)
• Book:Quantum Algebra and Quantum Computers (problems)

These reports are IMO cuter than those found on articles talk pages, so maybe you could talk to Josh Parris and see if having reports similar to those of books would be an acceptable solution, or at least an improvement. Headbomb {talk / contribs / physics / books} 18:09, 17 March 2010 (UTC)

It's the fact that they're a big splash-notice that's the problem, IMO, for reasons described above. --Christopher Thomas (talk) 18:16, 17 March 2010 (UTC)

Degenerate energy level

As I am not an authority on this subject in any manner, I wanted to bring this article to your attention instead of editing blindly myself. In the article Degenerate energy level, there is a sentence: "For example, in the Bohr model of the hydrogen atom, all of the states with the same angular momentum (which corresponds to them having the same principal quantum number) are degenerate." Okay, so, I thought that angular momentum was described by the azimuthal quantum number (l), but I didn't want to just go change the page myself, just in case the sentence is intentionally implying that all of the states of the Bohr model of the hydrogen atom inherently have the same principal quantum number (n) because they have the same angular momentum. I looked at the hydrogen atom page briefly, and I don't think an implication of that nature would be accurate, but I am not knowledgable enough to make that assessment. Anyway! In summation... have a look and fix it if need be! I know this is really trivial, so, sorry it's so lengthy. --Brittl33 (talk) 04:34, 20 March 2010 (UTC)

The angular momentum operator $L^{2}$ commutes with the Hamiltonian, and hence, angular momentum ($l$) and energy ($n$) quantum numbers are independent. Thus, for given value of angular momentum, you can have states corresponding to different energy levels. However, in the Bohr atom, the quantization condition is $l=n\hbar$, and hence, the value of the angular momentum uniquely fixes the energy quantum number ($n$). So the statement in the article is false in the full hydrogen atom, and vacuously true in the Bohr atom. SPat ^talk 05:06, 20 March 2010 (UTC)

Hot companion

FYI, there's a discussion at WT:ASTRO about the relatively recent article Hot companion.

70.29.210.242 (talk) 05:04, 20 March 2010 (UTC)

User:Systemizer

Systemizer (talk · contribs) seems to have returned from a long absence, and is making substantial changes to several cosmology-related articles. The ones at Dark energy (edit | talk | history | protect | delete | links | watch | logs | views) looked completely incorrect, so I've rolled them back. This appears to have happened elsewhere too, judging by talk-page warnings. If anyone with more time that I have at the moment would be willing to doublecheck their recent contributions, that'd be appreciated. I suspect there's still a fair bit of cleanup to do (and it's always possible that they've made valid contributions as well). --Christopher Thomas (talk) 09:24, 20 March 2010 (UTC)

Update: He's still at it, and has now blanked warnings issued by other editors. Most of the original synthesis seems to have been cleaned up, but the following changes are still present and could use vetting by people who are comfortable with the topics in question:

• Dark energy star (edit | talk | history | protect | delete | links | watch | logs | views) -- diff (edits by other users have been added since then)

As near as I can tell, all other questionable article-space changes have been rolled back. However, this user is very prolific (and now seems to be focusing on inserting essays into article talk pages, though there was the gem of moving metric expansion of space to metric impansion of space). --Christopher Thomas (talk) 05:59, 22 March 2010 (UTC)

"Free space" page needs attention urgently

The page Free space seems to be full of references to the pseudoscientific "aetherometry" theory, and has lots of instances of one particular editor/philosopher(!)'s view of the alleged impossibility of achieving a true vacuum. This is a guy called Correa who has been "in trouble" before for putting up loads of pages about his quack theory; see [[2]]

Also, one of the cited references next to one of these assertions of opinion links to an anti-wikipedia attack page run by Correa.

I have added numerous tags and am requesting that an expert in free space/vacuum and vacuum constants addresses this page. I don't know if the community is aware of the state of this "mid-importance" physics page, so I am drawing it to everyone's attention.

Liquidcentre (talk) 16:06, 24 March 2010 (UTC)

I do not know about all that, but I wonder why you think that it is possible to achieve a perfect vacuum? Evaporation or sublimation from the container walls cannot be entirely suppressed. Even intergalactic space contains some matter (albeit very sparsely). JRSpriggs (talk) 01:26, 25 March 2010 (UTC)

The article doesn't just say "you can't get a perfect vacuum because you can't reduce pressure all the way to zero" and "you can't get a perfect vacuum because you can't reduce temperature (i.e. photon density) all the way to zero". These things are true. But the article also says: "you can't get a perfect vacuum because there are always quantum-mechanical fluctuations", and that "free space" is what you get by taking away all the air, all the photons, and all the quantum-mechanical fluctuations. You're left with, allegedly, a region where Maxwell's equations hold exactly while quantum electrodynamics is only approximate. Moreover, this hypothetical region is said to be an important part of the definition of the metre and ampere -- i.e. a metre is the distance that light travels in 1/299792458 seconds in the classical vacuum. I strongly disagree with this.

The bulk of the article as it is currently written was written by User:brews ohare, who of course is currently banned from participating in this conversation. You can read my extensive debates with him on these points at Talk:Free space and judge for yourself based on Brews's own words rather than my biased perspective. :-) --Steve (talk) 06:32, 25 March 2010 (UTC)

There can be nontrivial effects when you impose certain boundary conditions, see e.g. here. Count Iblis (talk) 14:14, 25 March 2010 (UTC)

I don't think anyone is seriously disputing Count's point: after all, the Casimir effect (a "nontrivial effect when you impose certain boundary conditions") can be detected experimentally. The question is more about the presentation – we should not pretend that these quantum effects have more practical significance than they really do. We can be pretty sure that the speed of light in vacuum is constant down to a picometre scale, beyond that we're getting into guesswork but that is not a great catastrophe for physics! Possibly length is quantized at the microscopic scale, one day we'll find out, but for the time being it is fine to treat it as a continuous quantity – just as you electricity company (and the SI) treats electric charge as a continuous quantity, despite knowing that it's quantized at the microscopic scale.

I'm willing to have a go at writing the start of an article on the subject (I'd need some help from proper physicists for the advanced stuff): do we want to keep separate articles for free space and vacuum, or should we merge them? My preference is for the merge. Physchim62 (talk) 14:57, 26 March 2010 (UTC)

Picometre scale? Make that Planck scale![3] (I agree about merging articles, BTW.) ― ___A._di_M. (formerly Army1987) 15:46, 26 March 2010 (UTC)

I try not to deal with things smaller than atoms, they fall through the holes in my pocket ;-) Physchim62 (talk) 16:06, 26 March 2010 (UTC)

The Vacuum state article is more relevant as far as the QED effects are concerned, so we can move some stuff to there. Also, I'm surprised that Wikipedia does not have an article on vacuum birefringence as of yet. A simple article in which the formulas for the two indices of refraction to lowest order are given should not be too much work. Count Iblis (talk) 16:16, 26 March 2010 (UTC)

I don't think there needs to be any dedicated article on the "classical vacuum" (or "free space") as a "medium" where Maxwell's equations hold exactly (like the current free space article discusses). All the "properties of the classical vacuum" are really "aspects of classical electromagnetism", and discussed well in the various electromagnetism articles. I think one article, vacuum, would be an improvement. I could also imagine having two articles, "vacuum" and "perfect vacuum" (analogous to "ultracold" versus "absolute zero"). But the "perfect vacuum" article would be quite short, just saying that (1) this limit is useful for defining the meter and ampere, (2) this limit still contains interesting physics, with links to Casimir force, vacuum state, cosmological constant, etc. --Steve (talk) 16:47, 26 March 2010 (UTC)

Dynamics and Classical mechanics templates

I've copied them here but you can also see the issue where I first noticed it at Rotation around a fixed axis. Do these two templates both need to exist as they seem to cover essentially the same topics with the same articles; should they be merged or should one or other be deprecated. It's been mentioned before at Template talk:Dynamics but such pages tend to be rarely visited so better to raise it here.--JohnBlackburne^words_deeds 00:41, 26 March 2010 (UTC)

Agreed, I'd merge them into the latter. ― ___A._di_M. (formerly Army1987) 12:46, 26 March 2010 (UTC)

I think they need merging before one is deprecated. {{Classical mechanics}} is probably the better merge target, as it is the wider subject area. Given that the templates already use show/hide lists, there shouldn't be a problem with length. Physchim62 (talk) 14:27, 26 March 2010 (UTC)

Both templates are very similar. One has more internal links than the other. I agree that merging is best, and {{Classical mechanics}} is the better merge target because {{Classical mechanics}} has a broader scope that includes "Dynamics". Steve Quinn (formerly Ti-30X) (talk) 15:10, 26 March 2010 (UTC)

Yes merging would be best. I suggest keeping {{Classical mechanics}}, then redirect {{Dynamics}} to {{Classical mechanics}} once the merge is complete. (Then check if there are articles that link to both). Headbomb {talk / contribs / physics / books} 20:07, 26 March 2010 (UTC)

 Done (except checking for articles linking to both...) ― ___A._di_M. (formerly Army1987) 01:05, 27 March 2010 (UTC)

I took care of them. Headbomb {talk / contribs / physics / books} 01:23, 27 March 2010 (UTC)

Dark (something) star

User:RK wants to do some weird things with articles Dark energy star, Dark star and Dark matter star. See the talk pages for dark energy star and dark star.

76.66.194.32 (talk) 05:04, 23 March 2010 (UTC)

He raises a valid point. The logical thing to do is to make a disambiguation page, with dark energy star, dark star (dark matter), and dark star (Newtonian mechanics), as articles describing specific concepts. Even though the "dark star" term is no longer commonly used for Newtonian black holes, my understanding is that it was used in the literature before relativity changed the picture, making it historically relevant.

I'll apply "proposed move" templates to the present dark star article to get the ball rolling. --Christopher Thomas (talk) 06:57, 23 March 2010 (UTC)

While we're on the topic of merges and redirects below, comments about the proposed page move at Talk:Dark star#Disambiguation page would be handy. I want to make sure there aren't objections before I perform the move. --Christopher Thomas (talk) 21:51, 26 March 2010 (UTC)

Seems like we're missing a redirect... since User:RK thinks the dark energy star is a dark star, a redirect dark star (dark energy) should exist... 76.66.192.73 (talk) 05:09, 27 March 2010 (UTC)

I've seen the term "dark energy star" used in literature for that construct, but not the term "dark star". It's mentioned on the disambiguation page and linked from the hatnote, which should be enough for anyone who types "dark star" when they're looking for the dark energy concept. --Christopher Thomas (talk) 06:13, 31 March 2010 (UTC)

Update: Page move completed. I'm in the process of cleaning up links. Any that are left after the end of March, are ones I've missed. --Christopher Thomas (talk) 06:13, 31 March 2010 (UTC)

"Relativistic quantum mechanics" redirect

Relativistic quantum mechanics now redirects to Dirac equation, but IMO it'd make more sense to redirect it to Quantum field theory. What do you think about it? ― ___A._di_M. (formerly Army1987) 16:21, 28 March 2010 (UTC)

Agree. (And if not it should redirect to Klein-Gordon equation, rather than Dirac equation.) TimothyRias (talk) 18:11, 30 March 2010 (UTC)

 Done. ― ___A._di_M. (formerly Army1987) 12:57, 31 March 2010 (UTC)

Induced gamma emission: Hafnium controversy

At first glance, this article seems kosher. With my somewhat dated physics background, I delved a bit deeper, however, and received the strong impression the article was the synthesis of a few editors combining some actual research with large amounts of their own hypotheses and suppositions, dressed up a little with some fringe sources such as "imaginaryweapons.net".

So, using inline templates, I annotated the portions of the article that appeared to be synthesis, self-researched, or unverified, and attempted to start a discussion of the issues on the article talk page. Unfortunately, one of the article's clique of original editors refused to discuss the issues, began reverting my changes, and accused me of vandalizing the article.

If possible, I'd like another set of eyes of look at the article, and see if they reach the same conclusions I did. Thanks. FellGleaming (talk) 04:32, 31 March 2010 (UTC)

Long and long ago, there was an article called Hafnium bomb (edit | talk | history | protect | delete | links | watch | logs | views), which attempted to summarize this in a concise and neutral fasion. Then someone decided to merge it with Ballotechnics (edit | talk | history | protect | delete | links | watch | logs | views). It was around that point that I wrote it off as a loss and stopped tracking it, though it'd be nice to have a full description of the hypothesized induced emission and the controversy over whether or not it had actually been demonstrated. --Christopher Thomas (talk) 04:42, 31 March 2010 (UTC)

In addition to the original research and the conspiracy-theory tone the article is written in, the most serious problem seems to be whether or not any "hafnium controversy" even exists in the first place. There's no evidence of any controversy, or even serious disagreement, in the scientific community at all.FellGleaming (talk) 15:10, 31 March 2010 (UTC)

My understanding from the searching I'd done when writing the old stub was that one professor had claimed that you could cause samples of the isotope to dump all of their energy at once, while others claimed that no feasible device would be able to do this, and thought he was a bit eccentric for pushing it so hard. The existence of the metastable state wasn't disputed. It's been a few years, though, so I may be misremembering the details. --Christopher Thomas (talk) 18:26, 31 March 2010 (UTC)

Thanks Christopher. That makes sense. The article intro then should probably be written from that perspective, as the current revision seems intentionally obfuscated to prevent a lay reader from understanding what's actually being disputed. FellGleaming (talk) 18:28, 31 March 2010 (UTC)

I'd suggest cutting it down to about a quarter of its current length (to remove all the "oooh aaah" conspiracy theory stuff) then merging it into Induced gamma emission. Physchim62 (talk) 18:35, 31 March 2010 (UTC)

For comparison, here's my original stub. This was written in the days when generating content was considered more important than referencing it, so it wouldn't be suitable for incorporation without a lot of reference-searching. --Christopher Thomas (talk) 18:42, 31 March 2010 (UTC)

Thanks. Could I get you two to put your opinions on the article's talk? An overzealous editor is currently reverting any attempts to question the conspiracy-theory slant. FellGleaming (talk) 19:35, 31 March 2010 (UTC)

I'm not in a position to devote the required amount of time at present. If they're the only one doing this, you can make a case for them editing against consensus and also violating WP:OWN, but that only would hold water if there are several other editors whom they've been reverting. Assuming all of that is correct, the way to resolve this is to have an uninvolved editor from here go in, look through the article and history, move contested material to a new talk page thread, and give the conspiracy editor a formal warning about edit-warring and respecting consensus. When/if they revert, start an ANI thread to get administrator attention (as they'd at that point be breaking policy). In order for this to happen smoothly, it's vital to make sure you're respecting policy and not edit-warring yourself (most of the time, with these AN/I threads, all parties involved have been edit-warring). --Christopher Thomas (talk) 20:42, 31 March 2010 (UTC)