Wikipedia talk:WikiProject Physics/Archive December 2014

"Nature" free articles

I noticed this "Nature makes all articles free to view" which allows those that are subscribed to give a read-only PDF to people who are not subscribed. This should be helpful with the paywalled Nature papers that articles use for references, as the free-access PDF can be used as the URL link -- 67.70.35.44 (talk) 14:15, 2 December 2014 (UTC)

Incidentally, does anyone know how to use http://libgen.org that one of the commentators mentioned as an alternate? -- 67.70.35.44 (talk) 14:15, 2 December 2014 (UTC)

Are you sure that they intend to allow potentially millions of people to read these copies rather than just a few friends/coworkers of the subscriber? JRSpriggs (talk) 01:24, 3 December 2014 (UTC)

Well, the "Nature" subheadline says Publisher permits subscribers and media to share read-only versions of its papers. It would depend on if Wikipedia is covered by "media" or not. -- 67.70.35.44 (talk) 09:52, 3 December 2014 (UTC)

sklogwiki.org

Hi! A problem has come to light with sklogwiki.org, from which content has been copied in good faith, and with proper attribution, into several articles here: content on that wiki is licensed CC-BY-NC-SA, which unfortunately is not compatible here. I've had to remove content from Path integral molecular dynamics (there's some discussion on the talk page there), and have found similar incompatibilities at Andersen thermostat, Stockmayer potential and Patchy particles. All those articles need to be rewritten (if the topics are important): I don't know if other pages are also affected. I did wonder, though, if a simpler approach might be to ask sklogwiki to remove the "NC" ("non-commercial") restriction from its license, which would solve the problem; and if anyone here would like to undertake to do that? Justlettersandnumbers (talk) 00:13, 4 December 2014 (UTC)

It's not so simple to "ask sklogwiki". You'd have to ask every single contributor to all the articles in question to release their work under an additional license. And if you don't manage to do that for all of sklogwiki, you'd have to make clear to their editors and readers what's released under which license(s). I think rewriting our articles is the easier route. — HHHIPPO 07:43, 4 December 2014 (UTC)

Magnetic skyrmion

Hi, I have been doing a bit of gnoming and came across Magnetic skyrmion. It is not in a good state, citations, etc. This is beyond my ken, so I am bringing it to some expert attention here. Hamish59 (talk) 12:29, 5 December 2014 (UTC)

Energy systems/energy system

There's a redirect at Energy system redirecting to an ATP metabolism article. It occurs to me that there are many energy systems, and that this should lead elsewhere or be a disambiguation page. Do we have a general article or would it be energy ? (note also a discussion at talk:energy systems ) -- 67.70.35.44 (talk) 06:20, 7 December 2014 (UTC)

Physicists talk a lot about "energy" and about "systems", but I do not remember any case where they use the phrase "energy system". In a physics context, it seems to me to be too vague to be meaningful. JRSpriggs (talk) 09:56, 7 December 2014 (UTC)

Launch of WikiProject Wikidata for research

Hi, this is to let you know that we've launched WikiProject Wikidata for research in order to stimulate a closer interaction between Wikidata and research, both on a technical and a community level. As a first activity, we are drafting a research proposal on the matter (cf. blog post). Your thoughts on and contributions to that would be most welcome! Thanks, -- Daniel Mietchen (talk) 02:15, 9 December 2014 (UTC)

Open Access Reader, tool to find missing academic citations

Hi, I'm working on a project to find important academic citations missing from Wikipedia, which I think might be useful for this Wikiproject. It's just a proof of concept right now, but if you have any ideas or feedback, that'd be really helpful at this early stage. Check it out: Open Access Reader.

EdSaperia (talk) 13:18, 9 December 2014 (UTC)

Quality rating of article Jerk (physics)

Hi! I blanked the Start-Class-rating this article a while ago after I had done some -hopefully- improvements and just noticed that Meno25 re-evaluated it to Class C on 21.11.2014. He pointed me to here to place the following question: Please, can you can give me some hints to possibly increase the quality of this article in the direction to Class B, or point me to someone else to bother about this question? Thanks in advance. Purgy (talk) 10:37, 10 December 2014 (UTC)

I kinda disagree with the C-class rating there, though the rating system really needs to be broken down a bit more granularly so it's hard to say what's at what level. For example, there's a lot of material there (a plus), but only 6 in-line citations (a huge negative), 5 of which are bare URLs (an even bigger negative - use citation templates! {{cite}}). I also imagine that the article can be significantly trimmed and made more concise, and given a more encyclopedic feel. I don't have time to get into specifics now, but I suggest reading some of the featured articles and good articles under this WikiProject's scope to get a sense of what a high-quality article looks like. See perhapse Wind, Force or Kilogram.

In terms of getting people to look at it, I'm not familiar with the intimate details of these particular processes, but once you've given it a second pass (and seriously improved the referencing!), you may want to consider submitting it for peer review, and then maybe request a copy edit from the Guild of Copy-editors. I see from your user page that you've gotten involved with the Teahouse, that seems like a good start - there are a number of editors who focus on quality improvement and will take a start-class article and transform it into an FA-class article. If that's what you're interested in, maybe someone at the Teahouse can put you in touch with one of these editors who can give you a clearer path. 0x0077BE ^{(talk · contrib)} 19:44, 10 December 2014 (UTC)

Hi, @0x0077BE:, I take from your comment that I'd better strive to improve this article to real C level instead of looking for B. OK, I'll see what I can do. Thanks. Purgy (talk) 09:01, 11 December 2014 (UTC)

Featured error?

According to Signpost, this image (subject of the article Chronology of the universe) is now classified as a featured picture. However, it seems to me that it badly misrepresents the scale of the universe and its rate of change as functions of time. Or at least, no indication is given of how the horizontal and vertical axes should be interpreted. JRSpriggs (talk) 10:30, 19 November 2014 (UTC)

Not only that, but it doesn't even get the dimensionality of the universe right! Should be speedily deleted. Zueignung (talk) 10:43, 19 November 2014 (UTC)

I'm not sure if you mean the spatial dimensionality, but I think the x axis in that picture is supposed to roughly correspond to time, not physical dimension. 0x0077BE ^{(talk · contrib)} 11:49, 19 November 2014 (UTC)

I definitely don't think it should be speedy deleted, by the way, if anything a discussion should take place. If you guys think it's appropriate, I think the process for delisting is to list it for delisting at Commons:Featured picture candidates, where it needs 7 support votes to delist with at least 2:1 votes in favor of delisting. Personally, I feel like the language-dependence of the photo alone (only one version of a photo can be featured) should probably disqualify it as a featured picture, and honestly it doesn't look like anything special to me even ignoring any mistakes made. 0x0077BE ^{(talk · contrib)} 11:53, 19 November 2014 (UTC)

I doubt anyone thinks it should be speedily deleted (Poe's law seems to be well at work here). Zueignung (talk) 18:34, 19 November 2014 (UTC)

This is one of the standard images that's used by astronomers when talking about the history of the universe, so I think it's well worth keeping as a featured image here (thanks NASA for releasing their images into the public domain!). Sure, it's an illustrative diagram, and the X and Y axis shouldn't be taken too seriously, but it still gives a reasonable representation of the history of the universe. Is there a better representation around that could be used instead of this? Thanks. Mike Peel (talk) 20:31, 19 November 2014 (UTC)

NASA does not have much of choice in the matter, being a US government agency.TR 00:11, 20 November 2014 (UTC)

It was adapted from a diagram on NASA's website, which inclines me to think it's not completely crazy... What exactly do you think the problem is? My naive reading of the picture is that it suggests that the universe had grown to nearly its current size by 380,000 years after the big bang. Is that what it's supposed to show? Djr32 (talk) 20:40, 19 November 2014 (UTC)

I don't see much of a problem with it, it is an artistic interpretation of the chronology of the universe. Just add a description saying it is not drawn to a uniform scale / not drawn to scale. We have many artistic interpretations on Commons which we keep around without them being scientifically accurate. Just look at all the images of extrasolar planets and how their disc is proposed ot look like (including cloud bands and coloration). -- 67.70.35.44 (talk) 07:44, 20 November 2014 (UTC)

I should have been more specific about my objections. Generally, the time-axis (shown horizontally from left to right) should have some specified function which transforms the actual proper-time since the Big Bang to the distance from the left end of the picture. Similarly, the distance scale of the universe (a from Friedmann equations, shown vertically) should have some specified function which transforms the actual distance scale to the distance from the horizontal axis to the top edge of the "shot glass".

More specifically, the image gives the impression that the expansion of the universe suddenly stops (or slows-down greatly) at some time. This impression is false. During the inflationary era, the expansion is roughly exponential. When inflation ends, there is no sudden change in growth of the distance scale (that is, a and da/dt are continuous), but the expansion becomes roughly linear rather than exponential. That is, d²a/d²t changes from being proportional to a to being roughly zero.

To Djr32: No, the universe is much larger now (at +13.7 billion years) than it was at +380,000 years. JRSpriggs (talk) 06:50, 21 November 2014 (UTC)

The original image has the WMAP satellite drawn to be much, much larger than the galaxies pictured. What an egregious error! But seriously, this diagram is clearly meant to be schematic. If you want the article to have an accurate plot of a(t), go find one and insert it into the article. Zueignung (talk) 21:37, 21 November 2014 (UTC)

To Zueignung: Your sarcasm is not helpful. This picture is misleading people and you are trivializing the problems by equating them to obvious symbolism.

Many images in Wikipedia have problems, and we may not have the resources to fix most of them. However, such images should not be featured pictures. JRSpriggs (talk) 06:11, 22 November 2014 (UTC)

Yeah, JRSpriggs has a point. I agree that the picture makes it seem like the rate at which the universe was expanding suddenly dropped to zero at the end of inflation, while in fact it just stopped speeding up. Natsirtguy (talk) 00:09, 12 December 2014 (UTC)

M-theory

Hi everyone,

I just wanted to point out that M-theory is currently a good article nominee. It would be great if someone on here could review the article!

Thanks!

Polytope24 (talk) 18:44, 20 December 2014 (UTC)

Draft:Prigogine theorem

This old draft is still kicking around. I found more info at the non-equilibrium thermodynamics page, which implies that the Prigogine Theorem is essentially worthless. Should I reject it or is it a significant enough (invalid) theorem that it merits its own page? Primefac (talk) 23:39, 25 December 2014 (UTC)

This area of physics is conceptually very difficult or indeed ill-understood. It is easy to make dogmatic assertions in this area, but perhaps impossible in the present state of scientific knowledge to make statements that are known to be valid. No single source by itself can be regarded as reliable.

The Prigogine theorem for scenarios close to equilibrium is far from "essentially worthless". A narrowly defined valid theorem is far better than nothing. Its validity may well be disputed, but there is perhaps some literature consensus that it is valid.

Claims that it holds also for scenarios not close to equilibrium are, however, dubious at best, and should be viewed with very careful scepticism, and sources should be regarded as not reliable unless there is clear evidence of wide consensus. Claims that it holds for scenarios beyond physics, such as for the stock market, should be regarded even more sceptically. There is some reason to believe that the theorem does not hold beyond the original narrow scenario. Such a theorem, beyond the original narrow scenario, is probably fundamentally wrongly conceived and oriented.

I think the theorem should appear in the article on non-equilibrium thermodynamics, where it is evidently presented in moderately critical context. I think it should not have a page of its own, because of the present unsatisfactory state of scientific knowledge.Chjoaygame (talk) 00:16, 26 December 2014 (UTC)

Thanks for the input, I was leaning towards rejection and am glad to see it was the right decision. Primefac (talk) 04:51, 26 December 2014 (UTC)

Parsing errors

At least three supersymmetry related articles (Bogomol'nyi–Prasad–Sommerfield bound, Supergravity, Superconformal algebra) feature parsing errors. I am not sure what exactly is going wrong. --Omnipaedista (talk) 17:55, 24 December 2014 (UTC)

What parsing errors? Do you mean the display formulas which use <math>? If so, I do not see the usual red error messages. JRSpriggs (talk) 12:24, 25 December 2014 (UTC)

I see in all them red error messages beginning with "Failed to parse (Conversion error. Server ("http://mathoid.svc.eqiad.wmnet:10042") reported: "Error:["TeX parse error: Double subscripts: use braces to clarify"]"):" --Omnipaedista (talk) 00:07, 29 December 2014 (UTC)

Could you copy the source for one of the formulas which causes the error to this talk page so I can see which one it is? Since I am not seeing any errors like that. This might have to do with your preferences for displaying Latex or which server processes the page for you (just guessing). JRSpriggs (talk) 02:16, 29 December 2014 (UTC)

The problem arises only when I use Chrome; it works alright when I use Firefox so I guess you are right about your diagnosis. There follows a (nowikied) formula that causes error: <math>E=\int d^3x\, \left[ \frac{1}{2}\overrightarrow{D\varphi}^T \cdot \overrightarrow{D\varphi} +\frac{1}{2}\pi^T \pi + V(\varphi) + \frac{1}{2g^2}\operatorname{Tr}\left[\vec{E}\cdot\vec{E}+\vec{B}\cdot\vec{B}\right]\right]</math>. --Omnipaedista (talk) 04:37, 29 December 2014 (UTC)

It looked OK to me in Firefox (which I almost always use), so I switched to Chrome. But it looks OK to me in Chrome also.

$E=\int d^{3}x\,\left[{\frac {1}{2}}{\overrightarrow {D\varphi }}^{T}\cdot {\overrightarrow {D\varphi }}+{\frac {1}{2}}\pi ^{T}\pi +V(\varphi )+{\frac {1}{2g^{2}}}\operatorname {Tr} \left[{\vec {E}}\cdot {\vec {E}}+{\vec {B}}\cdot {\vec {B}}\right]\right]$

So perhaps it is your preferences or the cache for the page. Have you tried clearing your cache? What are your preferences for displaying Tex? JRSpriggs (talk) 07:36, 29 December 2014 (UTC)

I switched from "MathML with SVG or PNG fallback" to "PNG images" and the problem was solved. --Omnipaedista (talk) 09:09, 29 December 2014 (UTC)

Recent activity at Talk:Quantum mechanics

Hi!

There has been a storm of activity the past week (by few authors). I think we need more to chip in since the article is (ought to be) pretty vital in physics (and mathematics by extension to today's math-infested QM applications). The interested could perhaps have a look at Talk:Quantum mechanics#1920s quantum mechanics not obsolete. YohanN7 (talk) 11:59, 29 December 2014 (UTC)

WikiCup 2015

Hi there; this is just a quick note to let you all know that the 2015 WikiCup will begin on January 1st. The WikiCup is an annual competition to encourage high-quality contributions to Wikipedia by adding a little friendly competition to editing. At the time of writing, more than fifty users have signed up to take part in the competition; interested parties, no matter their level of experience or their editing interests, are warmly invited to sign up. Questions are welcome on the WikiCup talk page. Thanks! Miyagawa (talk) 21:54, 29 December 2014 (UTC)