Wikipedia talk:WikiProject Physics/Archive November 2012

Quantum state

More input desired here Talk:Quantum_state#A_question_about_the_lead_section. IRWolfie- (talk) 15:25, 2 November 2012 (UTC)

Interesting student projects?

Hi all,

I had a discussion today with a couple of academics from the University of Glasgow, who have organised for two students to work on improving small sets of physics articles as part of an assessed project. The project is likely to involve each one taking a particular low-quality core article and working on improving it to a reasonably good standard, along with its related articles, for a total of about a hundred hours of research/writing over several weeks; they'll be shown how to edit Wikipedia in advance and given plenty of examples of "good articles" to work from, so hopefully it should go reasonably smoothly.

At the moment, though, the supervisors are looking for subjects. Are there any standalone articles or groups of articles that you would suggest as potentially interesting topics for this sort of project? I'm quite aware that a well-chosen topic at the outset will make the project much more likely to succeed, and it'd be great to have input from people who're currently working in the area. Andrew Gray (talk) 23:57, 5 November 2012 (UTC)

Here are two good places to look:

• Wikipedia level 4 vital articles (Physics) (look for start-class articles)
• Top-importance, start-class articles in this Wikiproject

(It seems that there aren't any stubs among the highest-importance Physics articles.) RockMagnetist (talk) 00:12, 6 November 2012 (UTC)

Wikipedia:WikiProject Physics/Quality Control#Table of articles by quality and importance. Click on any of the table entries to see the corresponding list of articles. (RockMagnetist gave one of those links above.) The classifications are not terribly reliable though. Usually one person sets it, maybe very strangely, and then no one ever changes it because they don't think it's their place.

It would help to know...are these students college freshmen? Seniors? Interested in astrophysics? Physical chemistry? What? :-) --Steve (talk) 03:40, 6 November 2012 (UTC)

Anybody who is "moved by the spirit" to do so. You might get something useful from their user pages. Martinvl (talk) 04:37, 6 November 2012 (UTC)

Not unless you provide links for them! RockMagnetist (talk) 04:45, 6 November 2012 (UTC)

They're final-year undergraduates, I believe. As to their interests, I'm not completely sure - the supervisors were from an astrophysics background, but I don't believe this is the same for the students. Part of my thinking behind asking for general suggestions was that if we had some possible options in a range of fields, it might work better than just suggesting something based on what we thought they ought to like - if it's something where they go "oooh, I want to know more about that", you've already got half-way to the result ;-) Andrew Gray (talk) 15:59, 6 November 2012 (UTC)

So here's a few from my list. Spin-transfer torque is currently very short on the science side. Magnetoresistance and related articles are all patched together, could use some work. Same for Ferromagnetic resonance. Spin–orbit interaction could use a more detailed discussion of SOC in solid state systems. And Rashba effect is a terrible mess. Just a few from my sub-field. a13ean (talk) 16:14, 6 November 2012 (UTC)

Thanks! Magnetoresistance and related daughter articles looks like the sort of set I was envisaging. Andrew Gray (talk) 17:36, 7 November 2012 (UTC)

You have a similar request for clarification at WT:AST -- 65.92.181.190 (talk) 06:37, 7 November 2012 (UTC)

• Band diagram sorely needs writing. There's a whole field of knowledge about how they work: Electrons get pulled down, holes get pulled up, the tilt of the fermi level is related to net current flow, the location of the fermi level relates to the quantity of carriers, out-of-equilibrium devices will have split quasi-fermi-levels, and on and on. I think if you fully understand band diagrams, then you can fully understand almost everything in semiconductor device physics. :-)
• Characteristic x-rays should be written ... there is already a lot of writing on this subject on Wikipedia (e.g. K-alpha, K-beta, X-ray fluorescence, X-ray spectroscopy), but it would be worthwhile to merge all that (plus anything missing) into a unified dedicated article with some nice figures. :-) --Steve (talk) 16:51, 7 November 2012 (UTC)

Thanks - I've pointed the supervisors at this discussion. Band diagrams is an unexpectedly promising one; explaining something like this simply but comprehensively is a challenging task. The suggestion to get them working on figures is also interesting - if it's something they're able to do well, which will depend a bit on the individual, it could be really valuable. Andrew Gray (talk) 17:36, 7 November 2012 (UTC)

The Euler-Heisenberg Lagrangian article needs to be expanded. You can edit in examples of propagation of light in strong magnetic fields (e.g. near magnetars). Count Iblis (talk) 18:32, 7 November 2012 (UTC)

Fringe source

An editor, Iantresman was recently unbanned from Physics and Fringe articles. The editor is now proposing that the book "Physics of the Plasma Universe", which advocates plasma cosmology be included in an article about dusty plasmas. More input welcome at Talk:Dusty_plasma#Reference_restoration. IRWolfie- (talk) 20:00, 7 November 2012 (UTC)

Physics biography swap

Hi, I noticed that there are several important physicists in my sub-field which clearly pass WP:PROF but don't have pages here. I would rather not start them myself to avoid any possible COI as a graduate student working in field. I would like to propose the following: if anyone agrees that someone on this list meets WP:PROF and wants to write a short article about them, I will gladly start one about any notable physics-related subject or academic of your choice (although I might not be any help for articles on, say, string theory, since I'm an experimentalist). In no particular order here's a few to start, which I will expand as I think of others. Cheers a13ean (talk) 17:32, 9 November 2012 (UTC)

• Allan H. Macdonald -- Condensed matter theorist with named chair at UT Austin and lots of awards, silly number of publications, etc. Award CV h-index listing
• Hideo Ohno -- Condensed matter experimentalist: This one is a bit more tricky since much of the information on the subject is in Japanese, but the subject is notable for his groundbreaking work on Dilute magnetic semiconductors and is the head of a major research center google search.
• Charles L. Kane -- CM theorist noted for his work on quantum electronics including topological insulators and graphene, and won the Dirac Medal this year. Prize faculty page

Font recommendations?

A common convention in mathematics is to represent vectors by upright boldface symbols. However, Dger (talk · contribs) has pointed out that the convention for physical quantities is to always use italics:

Symbols for quantities are generally single letters set in an italic font, although they may be qualified by further information in subscripts or superscripts or in brackets.

— Bureau International des Poids et Mesures

Symbols for quantities are set in italic type, independent of the type used in the rest of the text.

— ISO 31-0

For example, irrespective of the typeface used in the surrounding text, “A” would be typed or typeset in ... italic boldface for the vector quantity vector potential: A.

— Guide for the Use of the International System of Units (SI) Section 10.2

The last quote in particular spells it out. In LaTeX the italic boldface can be implemented using \boldsymbol instead of \mathbf. Should this project make recommendations on typeface in physics documents? RockMagnetist (talk) 15:48, 14 November 2012 (UTC)

On the other hand,

Variables that denote vectors are set boldface, not italic.

— IEEE Computer Society Style Guide: Mathematical expressions

(although this quote applies to mathematical expressions, with no discussion of physical quantities). RockMagnetist (talk) 16:04, 14 November 2012 (UTC)

I'll just point out that bold italic vectors are a minority typesetting choice. Open up a Griffiths book, Halliday and Resnick, Serway and Jewitt, Physical Review Letters, or Physical Review D, and you will find bold upright vectors. This bold italic business is a "recommendation" or perhaps a "declaration", but not a "convention"—it is by and large not followed in the source works that Wikipedia draws from. The NIST document (i.e., the only one of the three that explicitly states that vectors should be bold italic) also states that tensors should be bold italic sans-serif. Now that's a style choice I don't think I've ever seen (except in MTW, where vectors are also bold italic sans-serif). In light of the fact that this is not a widespread convention, it is inappropriate to go around drive-by converting the formatting of these physics articles, as dger has done here, here, here, here, here, here, and here, among other places. These are changes that should be reverted but I worry that I will be fighting a losing battle without others to back me up. Zueignung (talk) 16:14, 14 November 2012 (UTC)

I agree it would be better to discuss it here before changing a lot of articles. I'm fairly neutral on this - I prefer the appearance of upright bold. Curiously, most style guides don't say anything about it (Physical Review Style and Notation Guide, for example). RockMagnetist (talk) 16:42, 14 November 2012 (UTC)

I'm neutral also, though would prefer upright-bold... which is the way everything is already. Changing to bold-italics could be done using the search-replace function in a text editor, though things are fine as they are. Maschen (talk) 16:48, 14 November 2012 (UTC)

I'd prefer ${\vec {r}}$ after all but that's probably not up for discussion, is it? -- Patrick87 (talk) 21:31, 14 November 2012 (UTC)

Actually over/under arrows are good notations because

• they are just as easy to typeset as bold,
• sometimes they are used in print, and
• much clearer in handwriting than simply underlines/twiddles since they indicate direction. If someone writes from WP, they are likely to use the convention the article uses (though bold symbols can't be handwritten easily they can be typeset)...

It's just that changing everything is silly, since there are so many notations for vectors with everyone having their preference... Maschen (talk) 22:04, 14 November 2012 (UTC) 

I prefer upright bold for the practical reason that I find it much easier to distinguish, at-a-glance, between vectors and scalars than any of the other conventions. But I agree with Maschen that we shouldn't embark on any bulk changes to existing articles.-- Dr Greg  talk  22:19, 14 November 2012 (UTC)

The problem with notation like ${\vec {r}}$ is that it starts to get messy if you want to add other symbols like tildes or dots overhead. RockMagnetist (talk) 22:23, 14 November 2012 (UTC)

Which is of course the advantage of using (upright-)bold. Maschen (talk) 22:27, 14 November 2012 (UTC)

The discussion so far is about 3-vectors. The bold upright convention is the one I prefer as it is widespread in the literature. There are also 4-vectors, the convention for which seem to be normal-italic. Xxanthippe (talk) 23:00, 14 November 2012 (UTC).

Usage seems to vary for 4-vectors. Rindler uses bold upright V. Penrose uses bold italic V. Of course everyone uses plain italic with index notation V^μ, if that's what you were referring to, but that makes sense as components of a vector.-- Dr Greg  talk  00:08, 15 November 2012 (UTC)

Over-arrows are more obvious than boldfacing for indicating vectors and have been used here (Force). I don't prefer this method but I was involved with a textbook that adopted this convention. There is no objection to using upright bold for vectors but it seems to me that italics should be used when the vectors are from the class of physical variables such as those listed here (ISO 31-3). I recently added these quantities to the table as it was empty a few days ago. I took much of this rule from my reading of the Metric Practice Guide that the Canadian Standards Association published some years ago as well as the documents mentioned earlier by RockMagnetist. The rule about vectors can and perhaps should apply to general mathematical vectors but may not be appropriate for vectors that represent physical quantities in equations such as Newton's Second Law, Pascal's Law, Archimedes Principle, etc. In these equations the variable names represent a particular class of physical quantities and should follow the ISO and SI standards, IMHO. It seems very odd to use italics for the scalars (i.e., magnitudes) of these quantities and then switch to upright when they represent the vector property of the quantity. It is very confusing to the unintiated. Actually, it seems confusing to most people it would seem. Dger (talk) 03:21, 15 November 2012 (UTC)

I have reverted the most recent formatting edits to the torque article. As has been demonstrated here, there is no consensus that bold italics are preferred, and several editors have expressed the opinion that we should not be mass-converting the formatting of existing articles. Zueignung (talk) 03:17, 16 November 2012 (UTC)

Let's agree to disagree on the vectors but the scalars must be in italics. There is no justification for using upright font for the quantity when the SI units are required to be in upright font. Wikipedia has selected the use of the SI system so we have little choice in the matter. As Dr Greg suggested it does make it easier to distinguish scalars from vectors. Frankly, I often had difficult distinguishing boldface from normal fonts. Dger (talk) 03:58, 16 November 2012 (UTC)

I think almost everyone uses italics for scalar variables; and italics for a subscript/superscript if it represents a variable (upright otherwise). RockMagnetist (talk) 04:19, 16 November 2012 (UTC)

I did find an explicit policy at Wikipedia:Boldface#Mathematics_variables that boldface variables should be upright; so any change in formatting would have to take that into account. RockMagnetist (talk) 04:14, 16 November 2012 (UTC)

"It seems very odd to use italics for the scalars (i.e., magnitudes) of these quantities and then switch to upright when they represent the vector property of the quantity. It is very confusing to the unintiated. Actually, it seems confusing to most people it would seem."

Sorry I don't understand this... as others have confirmed, there are so many books/journals that use upright-bold that people become very quickly accustomed to the notation (I know I did, surely everyone else?).

"Wikipedia has selected the use of the SI system so we have little choice in the matter"

Then why has WP use upright-bold everywhere and not italic-bold? Are there any rules "broken" here? Maschen (talk) 11:42, 17 November 2012 (UTC)

I agree that Wikipedia should follow common use and ignore standards organizations' (ISO / BIPM / etc) recommendations when the two disagree. (This has come up before, e.g. a debate a couple years ago about c vs c₀ for the speed of light in vacuum.) Standards organizations can be useful as a tie-breaker when there are multiple conventions that are each common enough in the real world. But bold-italic symbols for vectors (in 2d or 3d) are exceedingly rare in my experience. (All of the other options mentioned above are OK with me.)

And by the way, not all articles have to be the same. Even if we could make wikipedia physics fonts 100% internally consistent, it would only make readers all the more confused when they open a book that uses a different style. :-) --Steve (talk) 14:55, 17 November 2012 (UTC)

I reverted Momentum to upright bold. I found that putting five quotes around each inline vector led to some confusing wikitext, and other editors attempting to modify it left whole blocks of text italicized. It's not worth the hassle. RockMagnetist (talk) 19:19, 20 November 2012 (UTC)

Wikipedia:Articles for deletion/Quantum thermodynamics

Editors with interests in thermodynamics and statistical mechanics may be interested in this AfD. Xxanthippe (talk) 23:14, 17 November 2012 (UTC).

Estakhr's Constant (physics)

Can someone please take a look at this? I marked it for deletion because I found no book hits whatsoever. Smells like an elaborate hoax. Thanks! §FreeRangeFrog 20:15, 18 November 2012 (UTC)

if you found no book whatsoever, does not means that is a elaborate hoax, this physics article must deleted by scientific reason not by smells!. -- 65.255.37.193 (talk · contribs) 10:54, 22 November 2012‎ (UTC)

The burden of showing notability falls on the one asserting notability. JRSpriggs (talk) 05:21, 23 November 2012 (UTC)

NEED HELP

I wrote an article proving the existance and behavior of the graviton. I need to get the article in better shape. any help would be nice thanks. Gravitational wave detectors – Why do they fail?
Gravitons are mass-less particles with a spin of 2, capable of traveling at the speed of light
The problem is gravitons are emitted and travel with photons. Photons are mass-less with a spin of 1
Proof of this is in the fact that photons have no mass or charge and should not be affected by gravity
Yet, they bend even around suns which are not as massive as a black hole. This should be impossible unless the graviton is traveling with them.
As a second proof or aspect of this effect will show up when something is heated or agitated. It gives off photons and, will lose weight. An example of this is water it has a specific gravity of 1, when heated to steam the water has a specific gravity of .62 as it cools thru the exchange process, it will gain Back the gravitons and return to normal weight.
In conclusion photons are emitted taking gravitons with them both will have the same frequency when they hit a solid object. The photons and gravitons are either reflected or absorbed and will not penetrate to underground testing stations.

Alan Hess — Preceding unsigned comment added by Alan hess (talk • contribs) 05:26, 19 November 2012 (UTC)

Fixed line breaks, no change of content. — HHHIPPO 07:56, 19 November 2012 (UTC)

I'm not sure I get the point of the article: do you say gravity doesn't work underground? Either way, as a first step you should provide some reliable sources that show the topic is notable. Based on those, people can help you with the shape of the article. Note that it doesn't matter here if your proof is right or not, but it needs to be published and found notable elsewhere before it can be included in an encyclopedia. (See WP:OR for details). — HHHIPPO 07:56, 19 November 2012 (UTC)

Yet, they bend even around suns which are not as massive as a black hole. This should be impossible unless the graviton is traveling with them.

Or unless space is curved, which has been the prevailing theory for, well, a while. Also, "specific gravity" has, as far as your context is concerned, nothing to do with actual gravity. Water, when turned into steam, retains its mass. David (talk) 20:56, 20 November 2012 (UTC)

I don't see why there should be a separate article on why gravity detectors fail, that would be something that is covered in the gravity detector article. Or if there is so much information that we need a separate article, it would be gravity detector failure modes or similar. Wikipedia is WP:NOTFAQ not a Q&A service. -- 70.24.250.26 (talk)

I think that this thread should be treated as closed; the request for creation was declined. Wikipedia has pretty clear guidelines and policies which such an article would fall foul of because of this being an encyclopedia, such as WP:NOR and WP:N; it seems unlikely that either of these criteria would allow the article to be added, even with extensive work. This should however not stop this editor from contributing an article that satisfies the criteria. — Quondum 10:18, 26 November 2012 (UTC)