Wikipedia talk:WikiProject Physics/Archive January 2022

Electromotive force: uppercase or lowercase?

When abbreviating electromotive force as emf/EMF, do we use uppercase or lowercase?

I see that this has been asked on the article talk page in several sections without an entirely clear answer. The only somewhat clarifying comment I see (from Dicklyon in 2018) states that emf is more commonly seen in textbooks and style guides, which matches what I've seen (anecdotally), though capitalization recommendations are not consistent among other sources. The article on electromotive force uses primarily emf, though many linked articles use EMF, and I saw a handful of relatively recent edits (this, for example) changing capitalization, though it is unclear which is more correct.

Also, the uppercase EMF can also be used to abbreviate electromagnetic field, possibly a source of confusion if both terms appear in the same article. ComplexRational (talk) 22:25, 4 January 2022 (UTC)

Just to muddy the waters, I'll mention that the most common abbreviation I've seen for this in textbooks is a italicized SCRIPT E: ℰ PianoDan (talk) 22:45, 4 January 2022 (UTC)

Here's the n-gram stats. Looking at books, the recent rise of capped EMF is almost all about electromagnetic fields, it appears to me, while electromotive force is still usually emf. Dicklyon (talk) 01:56, 5 January 2022 (UTC)

@Constant314: You changed emf back to EMF. You have strong feelings about this question, or just what your edit summary said? Dicklyon (talk) 01:38, 5 January 2022 (UTC)

I try to stick with the manual of style. No strong feelings. Constant314 (talk) 03:31, 5 January 2022 (UTC)

Well, this is not an ordinary acronym, but something that appears almost always in all lowercase. OK? Dicklyon (talk) 06:10, 5 January 2022 (UTC)

Is there any reason not to just refer to it as "voltage"? Or is there a difference? JRSpriggs (talk) 17:32, 5 January 2022 (UTC)

Often "voltage" is reserved for a difference in static potential, whereas electromotive force may come from a changing magnetic field. --Trovatore (talk) 18:51, 5 January 2022 (UTC)

Comments welcome on Gravitational lens

See Talk:Gravitational lens#Half the value given by general relativity. Comments would be welcome. TIA. - DVdm (talk) 22:58, 9 January 2022 (UTC)

Articles needing attention

I've been looking at the "articles needing immediate attention" list, as opposed to the "articles needing expert attention." Membership in that list is generated when someone sets a flag on the project template on a talk page. But given that it's just a flag, what's the appropriate response when you get to a flagged page and there's no comment, and it's not obvious what the issue is? I mean, in theory, EVERY page that isn't GA needs attention. So what to do when confronted with a banner that says "needs immediate attention," and it's not obvious that the page is actually on fire? PianoDan (talk) 17:30, 11 January 2022 (UTC)

Just remove it. I took a look at Talk:Helium atom, where the flag was added in 2009; it was likely for concerns that have long been resolved. Actually, I think we should deprecate the parameter since it can be added without any obvious reason. –LaundryPizza03 (dc̄) 17:50, 11 January 2022 (UTC)

For reference, the category is Category:Physics articles needing attention. –LaundryPizza03 (dc̄) 17:55, 11 January 2022 (UTC)

Oh, yeah, thanks. It's interesting - the category is "needing attention", but the text in the template is "needs immediate attention.". PianoDan (talk) 18:05, 11 January 2022 (UTC)

Maybe "immediate" should be removed at Module:WikiProjectBanner/common data? 172.82.46.13 (talk) 15:27, 12 January 2022 (UTC)

Comments welcome about lowercase/uppercase at Talk:Van Cittert–Zernike theorem

Please see Talk:Van_Cittert–Zernike_theorem#Uppercase_or_lowercase_"van". Comments would be welcome. TIA. - DVdm (talk) 17:33, 12 January 2022 (UTC)

Negative Energy

Hey there, There are some issues with the Negative energy page, most of which are already mentioned in the Talk section. Basically, it flies rapidly between speculative and observable, and the distinctions between these two aren't very clear. There is also some information in the more fact-based sections that is questionable, and there aren't many sources. It doesn't seem like that specific page's viewers are capable of differentiating the difference and reducing confusion (this includes me).

There are also things that seem highly reductive and may not even be worth mentioning:

A universe in which positive energy dominates will eventually collapse in a "Big Crunch", while an "open" universe in which negative energy dominates will either expand indefinitely or eventually disintegrate in a "big rip".

From my amateur level of knowledge, that seems plausible, but we would have to assume that "negative energy" is actually something else (vacuum energy). It also doesn't account for other variables like geometry. Honestly, I'm not even sure how good my example is, but the article needs help! :)

Digzignition (talk) 17:16, 15 January 2022 (UTC)

Anti Scatter Grid articles

There's two articles on the same thing: Anti-scatter grid and Bucky-Potter grid. It's pretty obvious they should be merged, but any thoughts on which should be the article title, and which should be the redirect? PianoDan (talk) 22:01, 14 January 2022 (UTC)

@PianoDan, newer articles in Google Scholar (this century) use the term anti-scatter rather than Bucky-Potter, so I recommend "Anti-scatter grid" as the title. StarryGrandma (talk) 22:36, 14 January 2022 (UTC)

Ugh. When you said "this century", my first thought was "Who was doing medical X-rays in the 1800s?" Getting older is stupid. PianoDan (talk) 22:48, 14 January 2022 (UTC)

• Done - OK, I've combined the content of the two under "Anti-scatter grid", and blanked "Bucky-Potter Grid" as a redirect. PianoDan (talk) 18:35, 17 January 2022 (UTC)

Massive changes by editor obsessed with self-promotion

I've recently removed blatant self-promotion done by the SPA PhysicsVoice from a long series of articles: Schrödinger equation, Tests of general relativity, Quantum network, Quantum field theory in curved spacetime, Klein–Gordon equation, Gaussian beam, and ‎Schwarzschild geodesics. Now instead of simple adding a citation to his paper again, the editor is doing massive changes to the articles and adding a citation to his paper again. The changes are not particularly bad, but are not good either, and it's anyway clear that the point is simply to cite his paper. This happened in Schrödinger equation, Quantum field theory in curved spacetime, and Klein–Gordon equation (all already reverted). I'm asking for help because I don't have the time or the energy to deal with this myself. Tercer (talk) 11:11, 14 January 2022 (UTC)

Reply by PhysicsVoice (talk) 17:07, 14 January 2022 (UTC). : Wiki article on Quantum field theory in curved spacetime demands major revision regardless of what its citations are. The version that the above editors defend fails to provide the standard of scientific writing even at the level of elementary school. The main revision, should concisely introduce the theory in the lead of the article. The lead must be followed by an introductory section to justify the theory. Perhaps the best justification comes from Standard Model of particle physics and the standard model of cosmology. The introductory section should be followed by a section describing methods of extending quantum field theory from Minkowski space to a general Riemann geometry. The details, advantages and disadvantage of each approach should be emphasized in a separate subsection. Please feel free to add subsections. The outcome and prediction of the theory must be written a separate section too.

Among many other things the article in Schrödinger equation should stop referring to Klein-Gordon equation and Dirac equation as a general Schrödinger equation. Wiki articles are better to provide precise scientific language. Put in in simple words, apples and pears are fruits but we do not call pears as general apples. The same rule about naming applies to different partial differential equations.

In the scientific writing, please refrain of using adjectives such as "interesting", "important", "good" or "bad" and so on. There is a difference between science and poetry. Scientific writing should justify the theory, describe the methods in a clear language, and writes the prediction. Also please refrain from personal attack on other editors. PhysicsVoice (talk) 17:07, 14 January 2022 (UTC).

It's fine to include "interesting", "important", "significant", "satisfactory", etc. (and yes, even "good" and "bad") in scientific writing. The point of scientific writing is not to expunge all judgments. Per Wikipedia policy, we can record whether scientists have judged an idea to be "important", for example; we just can't make up that judgment ourselves. No one is saying that the current version of the Quantum field theory in curved spacetime article is perfect, but there are helpful and unhelpful ways of expanding it. XOR'easter (talk) 17:15, 14 January 2022 (UTC)

No encyclopedia entry should start by saying "Interesting new phenomena" occurs without saying what that entry is about. Come on! Use plain language to describe the theory and its predictions, and let the readers decide if they find the outcome interesting, important and etc. A scientific writing or an encyclopedia entry is not to violate the fundamental right of the readers about emotional evaluation of any subject ;)PhysicsVoice (talk) 17:26, 14 January 2022 (UTC).

I'm sorry, but what you're asking for just doesn't make sense. What "fundamental right" are we depriving anyone of by informing them that physicists do, in fact, find things like the Unruh effect interesting? XOR'easter (talk) 17:46, 14 January 2022 (UTC)

Any writing in any encyclopedia should be precise. The statement of "Most or some physicists evaluate Unruh effect interesting" can be added to an entry in encyclopedia. But the entry should be void of emotional feeling imposed by the writer. The entry can not attach emotional adjective to any entry. I stand firm "A scientific writing or an encyclopedia entry is not to violate the fundamental right of the readers about emotional evaluation of any subject ;)". — Preceding unsigned comment added by PhysicsVoice (talk • contribs) 18:03, 14 January 2022 (UTC)

Other than physicists, whose views is an article on an esoteric topic in advanced physics going to be talking about? I'm not going all-out in defense of the exact phrasing in a random article I had no part in writing, but I'm genuinely failing to follow your complaint. XOR'easter (talk) 19:15, 14 January 2022 (UTC)

Thanks. If you can't defend wording or the knowledge in a topic that you evaluate as esoteric, if I may say, maybe you should reflect why you keep reverting the edits of an editor with a knowledge of the subject PhysicsVoice (talk) 21:38, 14 January 2022 (UTC).

I have reverted some, but not all, of your edits because they introduced text that was less clear than what they replaced, cluttered the page with "clarification needed" tags that ignored the logic of the existing prose, and contained bad grammar (despite your insistence upon "plain English"). XOR'easter (talk) 21:47, 14 January 2022 (UTC)

On the other hand, removing a non-peer-reviewed source, as you did here, is fine, and I probably would have done that if nobody else had gotten to it first. Preprints on the arXiv aren't always bad; per the policy on self-published sources, they can be used if the author is an established subject-matter expert. Generally, in such cases, we want the author of the source to already have a Wikipedia article about them, so the reader can easily check who the author is. Also, you may get more constructive feedback by raising issues on the Talk pages of Wikipedia articles rather than tagging whole sections with "clarification needed"; the way you've been doing it, the argument for why clarification is needed gets lost in the edit history, and it's harder to have a conversation about it. Finally, don't abbreviate Wikipedia as wiki. That sets a lot of teeth on edge. Cheers, XOR'easter (talk) 22:28, 14 January 2022 (UTC)

OK, I'm trying to be friendly, but please stop pushing an agenda. Physicists actually do think of QFT on curved spacetime as an approximation to the as-yet-unknown theory of quantum gravity. See the Wald textbook, the citation to which you removed, or the volume edited by Bär and Fredenhagen: In particular, due to the weakness of gravitational forces, the back reaction of the spacetime metric to the energy momentum tensor of the quantum fields may be neglected, in a first approximation, and one is left with the problem of quantum field theory on Lorentzian manifolds. Surprisingly, this seemingly modest approach leads to far-reaching conceptual and mathematical problems and to spectacular predictions, the most famous one being the Hawking radiation of black holes. Or Kay (2006): One expects it to be a good approximation to full quantum gravity provided the typical frequencies of the gravitational background are very much less than the Planck frequency [...] and provided, with a suitable measure for energy, the energy of created particles is very much less than the energy of the background gravitational field or of its matter sources. Or Brunetti et al. (2016): Quantum field theory on curved spacetime, which might be considered as an intermediate step towards quantum gravity, already has no distinguished particle interpretation. Or Yang et al. (2020): Quantum field theory in curved spacetime is a semiclassical approximation to quantum gravity theory, where the curved background spacetime is treated classically, while the matter fields in the curved spacetime are quantized. XOR'easter (talk) 23:26, 14 January 2022 (UTC)

What is the paper that the redlink keeps inserting, so it can be assessed as a RS? Xxanthippe (talk) 02:05, 15 January 2022 (UTC).

Usually [1], but sometimes also [2]. Tercer (talk) 13:30, 15 January 2022 (UTC)

They are both arXiv papers so they are not reliable sources. Citations in GS are slender. Xxanthippe (talk) 02:04, 16 January 2022 (UTC).

They've both been reprinted in journals - the first one in Communications Physics, and the second in IJMP. However, that still doesn't make them WP:DUE. PianoDan (talk) 02:33, 16 January 2022 (UTC)

Correct. But the papers need to be significantly cited before they become notable enough for Wikipedia: WP:NOTTHENEWS. Some authors seem to assume that if they publish a paper on a subject, it can be immediately included in Wikipedia. False: Wikipedia articles on science are not review articles. There must be evidence that a paper has made an impact before it is included. Xxanthippe (talk) 03:34, 16 January 2022 (UTC).

Right there with you, believe me. PianoDan (talk) 18:47, 17 January 2022 (UTC)

Draft:Convergent beam electron diffraction

A review of this draft is requested. Should it be accepted as a separate article, or should the information be folded into electron diffraction? Is there enough information to warrant a separate article? McClenon mobile (talk) 19:17, 17 January 2022 (UTC)

On Schrodinger equation

The entry on Schrödinger equation within its subsection entitled quantum field theory says that "the general form of the Schrödinger equation is also valid in QFT, both in relativistic and nonrelativistic situations". The part of the quoted statement that implies the general form Schrödinger equation is valid in a relativistic field theory is misleading.

Please note Schrödinger equation is invariant under Galilean transformation. Galilean transformation are the symmetry group of Newtonian dynamics. Lorentz transformation which is required by special relativity does not keep Schrödinger equation invariant. In order to reconcile quantum mechanics with special relativity we need to move to a relativistic quantum field theory. The equations of motions of QFT are not "general Schrödinger equation" and experts in the field do not call them so. The most known equations are Klein-Gordon equation and Dirac equation. Schrödinger equation can be seen as the low energy limit of Klein-Gordon equation or Dirac equation.

Please use the proper terminology on the entry on Schrödinger equation. Every time that I try to use the proper terminology other editors revert it back. So kindly have it corrected PhysicsVoice (talk) 03:19, 16 January 2022 (UTC).

This isn't really the forum to discuss specific reverts on a given page - that's what the talk page of the article is for. PianoDan (talk) 03:24, 16 January 2022 (UTC)

Although the Schrödinger equation may have been originally intended and used in a Galilean invariant way, it is not limited to that. The Dirac equation is Lorentz invariant and also an instance of the time-dependent Schrödinger equation. JRSpriggs (talk) 18:11, 16 January 2022 (UTC)

Firstly, in mathematics, equations as form of functions are defined by their form over their domain. You can not define a function without saying what its domain is. The current definition of "the time-dependent Schrödinger equation" clearly suffers from not defining what its domain is. Dirac equation happens to be the only equation explicitly admitting Lorentz invariance resembling "the time-dependent Schrödinger equation" but it is applied over the domain of spinors. Dirac equation is not the same as the Schrodinger equation. Secondly, when an entry talks about the need to move toward quantum field theory then it should maintain neutral view about different approaches to quantum field theory. Within the section of quantum field theory in Schrödinger equation, it is not just and informative to single out the approach of the Schrodinger functional method over other methods. It should concisely express that there are many approaches, in one of them which is named as the Schrodinger functional method, the time evolution operator "resembles" the time-dependent Schrödinger equation. Resemblance does not mean that they are the same. — Preceding unsigned comment added by PhysicsVoice (talk • contribs) 19:12, 17 January 2022 (UTC)

The text already explains that the domain of definition depends upon the physical system being studied. Turning around and saying that a particular equation of the form $i\hbar \partial _{t}|\psi \rangle =H|\psi \rangle$ suddenly isn't a Schrödinger equation would be bizarrely self-contradictory. Moreover, I don't see how the Schrödinger functional formalism is being "single[d] out", apart from its being mentioned first. It certainly doesn't get much text devoted to it. XOR'easter (talk) 20:26, 17 January 2022 (UTC)

Op-Tec

So here's a weird one: OP-TEC Apparently the NSF awarded a grant a while back to develop a photonics education curriculum. There's lots of references to the materials, but the actual website is now... a Vietnamese online gambling platform? I can't decide if I think the underlying program is notable or not. Thoughts? PianoDan (talk) 22:31, 17 January 2022 (UTC)

Huh. Weird. There's a blurb here, and a fair number of primary but seemingly reviewed items, e.g., here. I'm not sure how much there is to say about it, but it also seems ... harmless to keep around, I guess? XOR'easter (talk) 23:20, 17 January 2022 (UTC)

How did you find that one, anyway? XOR'easter (talk) 23:25, 17 January 2022 (UTC)

I'm running through the list of physics articles that have been tagged with class (stub/start/etc...) but not importance and adding importance ratings. I've run across lots of interesting stuff. Also more fodder for my general dissatisfaction with WP:NACADEMIC, although I am NOT stepping on that landmine again any time soon.

I agree it's harmless, so I'll go ahead and add in those sources. Still wouldn't contest a PROD if someone else made one, though. PianoDan (talk) 23:33, 17 January 2022 (UTC)

Oh hey, you already added the sources. Cheers! PianoDan (talk) 23:34, 17 January 2022 (UTC)

Interesting approach. My only attempts at sifting through the obscure physics articles has been to find categories that sound like they would attract fringe-y stuff and skim through them for titles that sound odd. XOR'easter (talk) 00:55, 18 January 2022 (UTC)

Clearing the importance backlog for C-class articles

I have gone through and assigned an importance rating to every single unrated C-class physics article except for one. Would someone be so good as to go and rate the last one for me, just for completeness sake? Christine Aidala is a good friend of mine, so I shouldn't rate her article. Thanks! PianoDan (talk) 00:05, 19 January 2022 (UTC)

Additional request: Wow - I had no idea her sister had ALSO been elected an APS Fellow. Talented family! Would someone mind assigning an importance to Katherine Aidala as well? PianoDan (talk) 23:45, 19 January 2022 (UTC)

Draft:Generalized law of friction

Could someone help with this please? How real is it/, and is it important enough to be worked on? DGG ( talk ) 06:16, 20 January 2022 (UTC)

For convenience - Draft:Generalized_law_of_friction PianoDan (talk) 07:15, 20 January 2022 (UTC)

It's a remnant of an attempt to upload the complete works of Sosnovskiy to Wikipedia. See Wikipedia:Articles for deletion/Mechanothermodynamics for the whole story. TL;DR: you can delete it without a second thought. Tercer (talk) 08:30, 20 January 2022 (UTC)

Well, we can delete it in six months, because DGG reset the counter on {{db-g13}}... Primefac (talk) 11:51, 20 January 2022 (UTC)

Tagged for speedy deletion anyway. XOR'easter (talk) 19:06, 20 January 2022 (UTC)

Rfc about the periodic table in the lede of the PT article: 18 columns or 32?

Should the periodic table in the lede of the periodic table article have 18-columns or 32?

The rfc is here.

I thought I'd ask since the physicists have done so much to unpack the PT even though chemistry has not been reduced to physics.

Sandbh (talk) 22:15, 20 January 2022 (UTC)

Categorization up to date

It probably won't last, but for a brief shining moment, there are no "physics" tagged articles that are unrated for class and importance. PianoDan (talk) 18:28, 22 January 2022 (UTC)

Congratulations! XOR'easter (talk) 20:34, 22 January 2022 (UTC)

Nice! Reminds me I need to clear out the Astro unrateds... Primefac (talk) 13:43, 23 January 2022 (UTC)

Donald Gurnett, plasma physicist

I recently created an article for American plasma physicist Donald Gurnett, who died last week. Any help would be appreciated. Thank you, Thriley (talk) 19:31, 25 January 2022 (UTC)