Wikipedia talk:WikiProject Physics

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Contents


[edit] FAR listing for Plate tectonics

Plate tectonics has been nominated for a featured article review. Articles are typically reviewed for two weeks. Please leave your comments and help us to return the article to featured quality. If concerns are not addressed during the review period, articles are moved onto the Featured Article Removal Candidates list for a further period, where editors may declare "Keep" or "Remove" the article from featured status. The instructions for the review process are here. Reviewers' concerns are here.

[edit] Roche limit FAR

Roche limit has been nominated for a featured article review. Articles are typically reviewed for two weeks. Please leave your comments and help us to return the article to featured quality. If concerns are not addressed during the review period, articles are moved onto the Featured Article Removal Candidates list for a further period, where editors may declare "Keep" or "Remove" the article from featured status. The instructions for the review process are here. Reviewers' concerns are here.

[edit] Numerous errors in wikipedia's thermodynamics and statistical physics articles  :(

I have been editing and creating a few wiki articles on this subject recently. To my horror I frequently encounter very very stupid errors. One error that is repeated over and over again on many articles (I think I corrected them all by now) is the following erroneous statement:

dU\leq TdS - P dV \,

Which is supposed to follow from the fact that while dS\geq \frac{dQ}{T}, the work done by the system is dW = PdV. The latter is not true, of course. In general P dV \geq dW. This then led to the erroneous statement about the change in the internal energy. Now, it should have been clear to anyone that that inequality is problematic, because U is a a thermodynamic function of state that one should be able to uniquely specify by S and V see also here.

Now one can still argue that it is possible to get an inequality, but that is then not solely due to irreversible changes but rather due to the fact that the system would have to be described by more external variables than just the volume. But if one keeps all the relevant external variables and the corresponding generalized forces you always get the fundamental thermodynamic relation in the form of an equality.

Once a correct treatment derivation is given one can then go on to derive that e.g. the Gibbs energy of a system kept at constant T and P can only decrease. But that certainly does not follow form the nonsensical reasoning like "while dS\geq \frac{dQ}{T}, the work done by the system is dW = PdV".

It actually requires quite a bit of work to explain why the Gibbs energy can decrease. Also in textbooks one typically presents that discussion in terms of finite differences to stress the fact that one considers an initial state of a system in thermodynamical equilibrium and a final state, also in thermodynamical equilibrium. During the change the system is not assumed to be in thermal equilibrium, but the heath bath is assumed to always remain in thermal equilibrium.

One can then e.g. derive that the maximum amount of work in other forms than pressure-volume work that can be extracted from the system is given by minus the Gibbs energy change. And it should be clear that the Gibbs energy change is acounted for by the change in the product of the external variable that describes the change with its generalized force.

Count Iblis (talk) 17:29, 18 May 2008 (UTC)

Not really sure why you are posting this here. This page is usually used to invite contributions to on-going debates elsewhere...in this case I assume you are fixing as you find, since you give no links. This page gets archived relatively quickly; if you want the above thoughts recorded, best put them on a relevant article talk page (not to mention in Gibbs Energy). PaddyLeahy (talk) 18:03, 18 May 2008 (UTC)
...but good work, anyway! :) PaddyLeahy (talk) 18:06, 18 May 2008 (UTC)
Thanks! I just spotted similar problems at Helmholtz free energy which I have now largely fixed. The article on enthalpy also suffers from the same disease, I'll rewrite that page later. Count Iblis (talk) 02:09, 19 May 2008 (UTC)
It makes sense to post systematic issues here. --Starwed (talk) 06:00, 20 May 2008 (UTC)

[edit] The first Featured List ever for Physics!

The list of scientific publications by Albert Einstein is being considered as a Featured List. Please check it out and support it if you think it lives up to the criteria. Thanks! :) Willow (talk) 21:27, 20 May 2008 (UTC)

But only because you beat the List of baryons by speed. Damn you, and congrats!Headbomb (ταλκ · κοντριβς) 23:42, 20 May 2008 (UTC)

No, no, no — nothing's been decided yet about the list of scientific publications by Albert Einstein. I'm just pleading with people here to take a moment to review both of our lists; perhaps we'll be promoted together? :) I'll look at yours if you look at mine... ;) Willow (talk) 23:49, 20 May 2008 (UTC)

I already did :P. I'll vote as soon as I get a chance to review the comments.Headbomb (ταλκ · κοντριβς) 23:58, 20 May 2008 (UTC)

I supported the list, and made some revisions to list of baryons , which I hope you like. I was trying to make it more accessible to the average reader. Good luck to us both, Willow (talk) 18:45, 22 May 2008 (UTC)

[edit] J. Marvin Herndon

J. Marvin Herndon has recently created an article about himself and his work, and is actively editing it. As a result, the article is now flagged with COI and NPOV templates. I've been in email contact with him, but it would be good if more editors were involved on the article. Is there anyone here with experience with biographical and/or geophysical articles that could lend a hand? Thanks. Mike Peel (talk) 17:23, 24 May 2008 (UTC)

[edit] Vortex theory

I just saw an article that said the results of the Michelson–Morley experiment were the final nail in the coffin of the vortex theory, and — lo and behold! — vortex theory was a red link. How is anyone who's never heard of that discredited theory supposed to understand what was being said? That seems like a very surprising omission.

Another place where I came across this was not in Wikipedia. An article said that by 1700, Newton's physics was accepted throughout the whole civilized world. Another article, by a francophone author, said that, as difficult as it would be for his anglophone colleagues to understand, France is actually a part of "the whole civilized world". And moreover, he said, in 1700 many in France still believed in the vortex theory until a crucial test in the year 1733, financed by the French king, consisting of careful geodetic measurements, showed that the earth is oblate, as predicted by Newton's theory, rather than oblong, as predicted by the vortex theory. How can one understand what he's saying without knowing what the vortex theory was? Michael Hardy (talk) 02:43, 26 May 2008 (UTC)

The problem is that there are *two* "vortex theories"... The "real one" (which I honestly never heard of before, but see http://descartes.cyberbrahma.com/vortex.html which seems to indicate a certain reality), and the "crank one". I know wayyyy more than I should about the "crank one", which says that vortexes explain UFO propulsion, and they explain Tesla's results, and they prove that Einstein was wrong, Newton was wrong, Hawking was wrong, everyone was wrong except the patent holder of this new method of levitation and propulsion by means of gravito-magnetic vortex fluxions... linas (talk) 04:17, 31 May 2008 (UTC)
I just made your red link turn blue; however, the side effect may unfortunately be that the vandalism rate on mechanical explanations of gravitation will now increase 100-fold. linas (talk) 04:21, 31 May 2008 (UTC)
I love vortices.
linas (talk) 04:40, 31 May 2008 (UTC)

[edit] Cold fusion

Please give your thoughts at Talk:Cold fusion. - Dan Dank55 (talk)(mistakes) 18:00, 1 June 2008 (UTC)

Apparently, the most energetic editors of Cold fusion believe in it. The lead concludes "Since then, several reviews of the field published in peer-reviewed journals have concluded that cold fusion has been demonstrated by experiments which result in excess heat production and nuclear reaction products such as helium-4. Some experiments have shown low-level neutron production, X-ray emission, and transmutation of elements.". What a travesty. JRSpriggs (talk) 00:49, 2 June 2008 (UTC)

I agree that the article could really use a few more eyes. There is a User:Pcarbonn and an anonymous IP (possibly the same) who appear to be working very hard to give the article a tone more favorable to cold fusion than a rather critical 2004 DOE report. PCarbonn is very interested and informed about the topic, and quite willing to work with references, but in my opinion tends to interpret references and their significance in a much more favorable light toward cold fusion than most scientists would read them. It seems to be getting difficult to keep the talk page from degenerating into a debate over cold fusion. Gnixon (talk) 15:08, 2 June 2008 (UTC)

Agreed with all of that. I worked closely with Pcarbonn during the review, and I was happy with the end product of the review on the 29th. We finally have a vigorous conversation on the article talk page, so I've changed the link above to point there, for people who want to weigh in. - Dan Dank55 (talk)(mistakes) 16:35, 2 June 2008 (UTC)
Okay, thanks, we got enough participation on the talk page that I felt comfortable editing the lead myself. - Dan Dank55 (talk)(mistakes) 18:15, 2 June 2008 (UTC)
One more thing: we need some help from someone comfortable with quantum chemistry or physics to insert a couple of sentences to balance the sentence in the lead that says that some consider cold fusion to be consistent with textbook physics. Volunteers are encouraged to leave a message either on the article talk page or my talk page. - Dan Dank55 (talk)(mistakes) 18:28, 5 June 2008 (UTC)

[edit] Request for help at quantum articles

There is a dispute. Please see Talk:Shor's algorithm and Talk:Quantum computer. Skippydo (talk) 15:19, 4 June 2008 (UTC)

[edit] Request for help at Siphon

There is a debate on Talk:Siphon that is going around in circles.--Yannick (talk) 14:21, 7 June 2008 (UTC)