Wikipedia talk:WikiProject Physics/Archive January 2023

RM for Anti-de Sitter space with highly visible consequences

I have opened a move request at Talk:Anti-de_Sitter_space#Requested_move_1_January_2023, which would require a spelling change across a large number of articles related to general relativity or string theory. In particular, AdS/CFT correspondence which is currently featured at WP:OTD on the Main Page, would be affected. –LaundryPizza03 (dc̄) 10:38, 1 January 2023 (UTC)

Talk:Gauge covariant derivative#Reversion of the edits on Gauge covariant derivative and its relation to Gaige transformations

User:RogierBrussee argues that because he claims to have the qualification of a PhD (no less) he has enough expertise not to be required to support his edits with sources. Editors are invited to comment on this claim, and also on the edits themselves. Xxanthippe (talk) 02:53, 2 January 2023 (UTC).

My observation is that this significantly misrepresents the comments made by RogierBrussee. See the discussion at WP:RSN. I am not qualified to comment on the edits themselves as the subject matter is beyond my own expertise. Banks Irk (talk) 21:42, 2 January 2023 (UTC)

SPA warrior

Anyone interested in combating an edit warrior who seems to be new to WP and is using the name of one author (Alessandro Settimi) of an almost uncited 2013 paper, repeatedly inserting a reference to the paper into Magnetic monopole? See [1], [2], [3], [4]. —Quondum 20:48, 3 January 2023 (UTC)

Reverted as not having provided sources for the encyclopedic significance of the paper they promote at such length, warned for promotion. NebY (talk) 21:13, 3 January 2023 (UTC)

Appreciated. I'll keep a watch for a while. Hopefully they will heed the warnings. —Quondum 17:20, 4 January 2023 (UTC)

Redshift

I just noticed Redshift on the list of articles that became Featured a long time ago and need review. The intro paragraphs are rather choppy, which suggests that bits and pieces have been added without an overall plan; the citation formatting is not entirely uniform; it's old enough that it talks about WMAP but not Planck; it cites a couple ancient press releases, which ought to be evaluated to see if they need supplementing or replacing. XOR'easter (talk) 16:41, 16 January 2023 (UTC)

There's also a fairly lengthy derivation that looks rather textbook-ish and could perhaps be condensed. (I think it's more encyclopedic to explain the assumptions, result, and significance of a calculation than to show its steps.) Thoughts? XOR'easter (talk) 17:56, 17 January 2023 (UTC)

Condensed or even eliminated - it doesn't seem encyclopedic at all. PianoDan (talk) 20:04, 17 January 2023 (UTC)

I concur. Derivations are not generally appropriate in WP. Explaining what something belongs here, but not how to show it, prove it, or otherwise understand its details. Besides, they make it more unreadable. —Quondum 22:34, 17 January 2023 (UTC)

Center of mass (relativistic) – delete?

Am I off my rocker, or is the article Center of mass (relativistic) complete bollocks? (I won't bite if you tell me the former holds.) It seems to me that any sensible definition of an isolated confined system in special relativity (i.e., Minkowski space with conservation of energy–momentum) must lead to a unique straight world-line that gives the centre of mass. If so, the article should be deleted. —Quondum 22:06, 9 January 2023 (UTC)

You are right. It is total crap. Another attempt by an anti-relativist to undermine the theory of relativity by misrepresentation. JRSpriggs (talk) 10:31, 10 January 2023 (UTC)

PRODed. It is easy enough to find a way of expressing the problem in a Lorentz-invariant way. (Though I am a non-expert and not rigorous in my approach, I would welcome a debate with the author(s).) There is also quite evidently WP:COI at play (self-citing own papers from WP) by essentially a WP:SPA. —Quondum 02:46, 11 January 2023 (UTC)

Thanks. How did that weird article survive so long? --mfb (talk) 05:38, 11 January 2023 (UTC)

I find the article Velocity-addition formula to be similarly weird, starting with the title: it is not addition, but composition, and makes unstated or unclearly stated frame-specific assumptions. It reads like a collaborative project by first-year physics students who have not yet grokked four-velocity as a world-line tangent vector. If it was notable, you'd think modern texts would all mention it. —Quondum 13:18, 11 January 2023 (UTC)

I can attest to the basic velocity-addition formulas, under the name Lorentz velocity transformations as well as the informal description as addition of velocities, as Eqs. 2.23–24 in my own undergraduate textbook on special relativity, Thornton & Rex 4th ed. Regardless, the vast majority of the content should be abridged per WP:NOTTEXTBOOK. –LaundryPizza03 (dc̄) 14:25, 11 January 2023 (UTC)

The article creates the impression that this is how the problem is typically or can reasonably be approached, despite its tendency to confuse Lorentz boosts with velocities. It seems to be talking about the composition of Lorentz boosts as parameterized by velocity, but non-collinear Lorentz boosts do not compose to another pure Lorentz boost, which cannot thus be parameterized by a velocity. This should be dealt with in a section of Lorentz transformation, which it already is. The article has seen a period when Ungar's weird gyrovector space idea was given prominence, since removed from this article. To give an analogy, this no different from an "angle addition formula" on a sphere, where this "addition" is defined as the composition of a rotations around different axes through the centre of the sphere. Anyone would recognize this as an incomplete and ridiculous way to work with the group of rotations in three dimensions in terms of one-dimensional "angle" parameters. If a modern textbook talks about it, it should be only as an example of how not to think about it. —Quondum 16:27, 11 January 2023 (UTC)

The addition of velocities terminology is commonplace; see, for example, the Feynman Lectures, where chapter 16 of volume 1 covers the addition of velocities in relativity [5]. Mermin's introductory text on special relativity gives the relativistic velocity addition law in Eq. (4.2) [6] and has a lengthy discussion of the topic. The article isn't in very good shape, but the problems don't include the title. XOR'easter (talk) 18:26, 12 January 2023 (UTC)

I should withdraw my objection to established terminology used in pedagogical contexts. And I should avoid side-tracking this thread onto a examples of what I find weird. —Quondum 18:59, 12 January 2023 (UTC)

No worries! The page does need attention, so it's good that you pointed it out here. XOR'easter (talk) 14:22, 14 January 2023 (UTC)

References

That article creator had an article on their User page that I just moved to Draft space. You can find it at Draft:Instantaneous 3-spaces in Non-Inertial Reference Frames. Feel free to improve it or mark it as a hoax if you also think it is bogus. Liz ^{Read! Talk!} 02:59, 18 January 2023 (UTC)

Liz, that editor's last edit was in April 2016. It appears to qualify for immediate deletion under WP:G13. The text is somewhat surreal to read (what does it even say?), is completely unsuitable for an article and is likely unsalvageable, I can't even figure out what the title tries to capture and deleting it will not be a loss. It is not a hoax, but it does seem to be the ramblings of someone who has failed to grasp important basics of relativistic physics. —Quondum 13:32, 18 January 2023 (UTC)

Unreviewed Featured articles year-end summary

Restoring older Featured articles to standard:

year-end 2022 summary

Unreviewed featured articles/2020 (URFA/2020) is a systematic approach to reviewing older Featured articles (FAs) to ensure they still meet the FA standards. A January 2022 Signpost article called "Forgotten Featured" explored the effort.

Progress is recorded at the monthly stats page. Through 2022, with 4,526 very old (from the 2004–2009 period) and old (2010–2015) FAs initially needing review:

• 357 FAs were delisted at Featured article review (FAR).
• 222 FAs were kept at FAR or deemed "satisfactory" by three URFA reviewers, with hundreds more being marked as "satisfactory", but awaiting three reviews.
• FAs needing review were reduced from 77% of total FAs at the end of 2020 to 64% at the end of 2022.

Of the FAs kept, deemed satisfactory by three reviewers, or delisted, about 60% had prior review between 2004 and 2007; another 20% dated to the period from 2008–2009; and another 20% to 2010–2015. Roughly two-thirds of the old FAs reviewed have retained FA status or been marked "satisfactory", while two-thirds of the very old FAs have been defeatured.

Entering its third year, URFA is working to help maintain FA standards; FAs are being restored not only via FAR, but also via improvements initiated after articles are reviewed and talk pages are noticed. Since the Featured Article Save Award (FASA) was added to the FAR process a year ago, 38 FAs were restored to FA status by editors other than the original FAC nominator. Ten FAs restored to status have been listed at WP:MILLION, recognizing articles with annual readership over a million pageviews, and many have been rerun as Today's featured article, helping increase mainpage diversity.

Examples of 2022 "FAR saves" of very old featured articles

Solar System 2007 FA J. K. Rowling 2007 FA June 26, 2022 TFA Antarctica 2006 FA Joan of Arc 2006 FA Speed of light 2010 FA

All received a Million Award

But there remain almost 4,000 old and very old FAs to be reviewed. Some topic areas and WikiProjects have been more proactive than others in restoring or maintaining their old FAs. As seen in the chart below, the following have very high ratios of FAs kept to those delisted (ordered from highest ratio):

• Biology
• Physics and astronomy
• Warfare
• Video gaming

and others have a good ratio of kept to delisted FAs:

• Literature and theatre
• Engineering and technology
• Religion, mysticism and mythology
• Media
• Geology and geophysics

... so kudos to those editors who pitched in to help maintain older FAs !

FAs reviewed at URFA/2020 through 2022 by content area

FAs reviewed at URFA/2020 from November 21, 2020 to December 31, 2022 (VO, O) Topic area Delisted Kept Total Reviewed Ratio Kept to Delisted (overall 0.62) Remaining to review for 2004–7 promotions Art, architecture and archaeology 10 6 16 0.60 19 Biology 13 41 54 3.15 67 Business, economics and finance 6 1 7 0.17 2 Chemistry and mineralogy 2 1 3 0.50 7 Computing 4 1 5 0.25 0 Culture and society 9 1 10 0.11 8 Education 22 1 23 0.05 3 Engineering and technology 3 3 6 1.00 5 Food and drink 2 0 2 0.00 3 Geography and places 40 6 46 0.15 22 Geology and geophysics 3 2 5 0.67 1 Health and medicine 8 3 11 0.38 5 Heraldry, honors, and vexillology 11 1 12 0.09 6 History 27 14 41 0.52 38 Language and linguistics 3 0 3 0.00 3 Law 11 1 12 0.09 3 Literature and theatre 13 14 27 1.08 24 Mathematics 1 2 3 2.00 3 Media 14 10 24 0.71 40 Meteorology 15 6 21 0.40 31 Music 27 8 35 0.30 55 Philosophy and psychology 0 1 1 – 2 Physics and astronomy 3 7 10 2.33 24 Politics and government 19 4 23 0.21 9 Religion, mysticism and mythology 14 14 28 1.00 8 Royalty and nobility 10 6 16 0.60 44 Sport and recreation 32 12 44 0.38 39 Transport 8 2 10 0.25 11 Video gaming 3 5 8 1.67 23 Warfare 26 49 75 1.88 31 Total 359 Note A 222 Note B 581 0.62 536 Noting some minor differences in tallies: A URFA/2020 archives show 357, which does not include those delisted which were featured after 2015; FAR archives show 358, so tally is off by at least one, not worth looking for. B FAR archives show 63 kept at FAR since URFA started at end of Nov 2020. URFA/2020 shows 61 Kept at FAR, meaning two kept were outside of scope of URFA/2020. Total URFA/2020 Keeps (Kept at FAR plus those with three Satisfactory marks) is 150 72 = 222.

But looking only at the oldest FAs (from the 2004–2007 period), there are 12 content areas with more than 20 FAs still needing review: Biology, Music, Royalty and nobility, Media, Sport and recreation, History, Warfare, Meteorology, Physics and astronomy, Literature and theatre, Video gaming, and Geography and places. In the coming weeks, URFA/2020 editors will be posting lists to individual WikiProjects with the goal of getting these oldest-of-the-old FAs reviewed during 2023.

Ideas for how you can help are listed below and at the Signpost article.

• Review a 2004 to 2007 FA. With three "Satisfactory" marks, article can be moved to the FAR not needed section.
• Review "your" articles: Did you nominate a featured article between 2004 and 2015 that you have continuously maintained? Check these articles, update as needed, and mark them as 'Satisfactory' at URFA/2020. A continuously maintained FA is a good predictor that standards are still met, and with two more "Satisfactory" marks, "your" articles can be listed as "FAR not needed". If they no longer meet the FA standards, please begin the FAR process by posting your concerns on the article's talk page.
• Review articles that already have one "Satisfactory" mark: more FAs can be indicated as "FAR not needed" if other reviewers will have a look at those already indicated as maintained by the original nominator. If you find issues, you can enter them at the talk page.
• Fix an existing featured article: Choose an article at URFA/2020 or FAR and bring it back to FA standards. Enlist the help of the original nominator, frequent FA reviewers, WikiProjects listed on the talk page, or editors that have written similar topics. When the article returns to FA standards, please mark it as 'Satisfactory' at URFA/2020 or note your progress in the article's FAR.
• Review and nominate an article to FAR that has been 'noticed' of a FAR needed but issues raised on talk have not been addressed. Sometimes nominating at FAR draws additional editors to help improve the article that would otherwise not look at it.

More regular URFA and FAR reviewers will help assure that FAs continue to represent examples of Wikipedia's best work. If you have any questions or feedback, please visit Wikipedia talk:Unreviewed featured articles/2020/4Q2022.

FAs last reviewed from 2004 to 2007 of interest to this WikiProject

If you review an article on this list, please add commentary at the article talk page, with a section heading == [[URFA/2020]] review== and also add either Notes or Noticed to WP:URFA/2020A, per the instructions at WP:URFA/2020. If comments are not entered on the article talk page, they may be swept up in archives here and lost. SandyGeorgia (Talk) 16:50, 19 January 2023 (UTC)

1. Edward Teller
2. Louis Slotin
3. Redshift

Spin 3/2 and 5/2 fermions

Greetings! Does anyone know if spin 3/2 or 5/2 fermions have been empirically shown to exist, or are they purely theoretical? Other than the rotational symmetry, are they different in any qualitative way from spin 1/2 fermions? I'm asking because Spin 3/2 and Spin 5/2 redirect to Fermion, and they are not explained there. (Spin (physics)#Higher spins only has math which is meaningless to almost all readers.) -- Beland (talk) 19:44, 23 January 2023 (UTC)

Atomic nuclei with odd mass number are fermions (as composite particles are included in the definition), and as an example, lithium-7 has a spin of 3/2−. There are a number of nuclei with higher half-integer spins as well. ^Complex/_Rational 19:58, 23 January 2023 (UTC)

There are baryons (baryons are fermions) with these larger half-integer spins. See Delta baryons and Sigma baryons. Again, these are in some sense a composite of "elementary" fermions. —Quondum 21:19, 23 January 2023 (UTC)

"speed of light in vacuum" vs. "speed of light in a vacuum"

If anyone cares which version WP "should" use, you may wish to comment at Talk:Metre#Really?. —Quondum 20:17, 18 January 2023 (UTC)

Some stats for interest only, not apropos any specific article: preference between these versions of the phrase shows a distinct change with scholarliness, from roughly even in general use to strongly one-sided in scholarly/academic use, even though both forms are common enough to be regarded as "correct English". Here are some sample statistics:

• ngram: [7] roughly even, a small edge to the first around the time of the introduction of the SI
• Google first bunch [8] counting first ~20 gives roughly 1:1 ratio
• GScholar first 50 [9] counting first ~50 listed gives roughly 8:1 ratio
• GScholar: ~60k vs. ~20k
• nist.gov 1240 vs. 384
• bipm.org: 69 vs. 2

—Quondum 01:06, 30 January 2023 (UTC)

Is there a difference between US English and UK English? If there is is probably still does not help us to decide? --Bduke (talk) 05:51, 30 January 2023 (UTC)

My impression is that usage is not highly dependent on which region one considers. In any event, I am not looking to argue any issue. —Quondum 15:22, 30 January 2023 (UTC)

FAR for uranium

I have nominated Uranium for a featured article review here. Please join the discussion on whether this article meets the featured article criteria. Articles are typically reviewed for two weeks. If substantial concerns are not addressed during the review period, the article will be moved to the Featured Article Removal Candidates list for a further period, where editors may declare "Keep" or "Delist" in regards to the article's featured status. The instructions for the review process are here. Hog Farm _Talk 18:35, 30 January 2023 (UTC)