Wikipedia:Featured article review/Laplace–Runge–Lenz vector/archive1

The following is an archived discussion of a featured article review. Please do not modify it. Further comments should be made on the article's talk page or at Wikipedia talk:Featured article review. No further edits should be made to this page.

The article was kept by Nikkimaria via FACBot (talk) 3:33, 5 July 2021 (UTC) [1].

Laplace–Runge–Lenz vector[edit]

Notified: WillowW, WikiProject Mathematics, WikiProject Physics, Diff of talk page notice, 2021-04-17

I have a number of concerns about this article's compliance with the FA criteria. First and foremost (as pointed out by Hog Farm), many places are entirely unsourced; this presents serious concerns under criterion 1c. Additionally, some of the sources that do exist are of questionable reliability: many are quite old (two are from 1710, while others are from 1847, 1859, 1891, 1901, 1915, 1919, 1923, etc.). The article is also nearly impossible to understand without a graduate-level mathematics education (some of this is inevitable given the topic, but more "engaging" prose is likely required nonetheless), and a quick perusal yields a self-reference ("as described elsewhere in this article") and numerous unnecessary duplinks. Extraordinary Writ (talk) 21:03, 29 May 2021 (UTC)[reply]

"As described elsewhere in this article" is completely different from what is described at MOS:SELFREF -- all it needs is an appropriate section link (as in Template:Section link). And mathematical truths are not time-dependent, so there is no reliability whatsoever with using historical sources. (There may be other reasons to prefer more modern sources, though -- like the primary vs. secondary distinction, or to ensure due weight.) --JBL (talk) 21:18, 29 May 2021 (UTC)[reply]

Yes, it's a historical topic, deeply rooted in the development of classical mechanics and of significant importance for quantum physics as well, so historical references are good things. They shouldn't be the only citations, of course, and they aren't. There's repeated use of Hall's 2013 textbook, for example, and seven references to Goldstein. The topic is one that a physics student would encounter in a graduate course, and so per WP:ONELEVELDOWN, it ought to be accessible to advanced (or courageous) undergraduates. It needn't teach what vectors are, but it shouldn't presume knowledge of symplectic manifolds. For the most part, it hits this mark. (I'd say that it gets slightly harder at § Poisson brackets, but there's not a lot that can be done about that; that's just the material.) A few more pointers to textbook chapters where details are derived and discussed might be helpful. XOR'easter (talk) 00:23, 30 May 2021 (UTC)[reply]

(The following comments should not alter it's FA status, which seems fine to me.) My complaint is that perhaps its written at too low a level, not too high a level. My impression is that all of the formulas are written at a level accessible to undergraduates in physics/math. (The original author who created the FA article -- User:WillowW was an undergrad, and did not have a formal background in advanced mathematics/physics. This is definitely not "grad level" stuff, which is why its a bit weak in places. It's peddling as fast as it can in first gear, never shifts into second.) What's missing is a slightly more advanced treatment of the group manifold. Right now, as it stands, the article notes that the lie algebra generated by L_i, D_i can generate the Lie groups SO(4), SO(4)/Z_2, SO(3)xSO(3) and SO(3,1). That's fine, but the relationships between these is less than entirely clear. (well, actually SO(3)xSO(3) does not seem correct!?) Where does the Z_2 come from, or rather, why does it go away? Why isn't there a SO(3,1)/Z_2? What happens in the parabolic case (in the conventional sense of elliptic==bound orbits, hyperbolic==unbound orbits), where the manifold flops from SO(4) to SO(3,1)? I guess that for the parabolic case, the manifold is SO(3)xR? It would be nice to see how this manifold flops over as a function of the energy. What's the quantum mechanics of the hydrogen atom at n=infty, right at that limit point where the discrete spectrum flops over into the continuous spectrum? What's the spectral density? (The ~~spectral density~~ density of states is the number of energy levels N=N(E) per unit energy interval: dN/dE. For bound states, it is a sequence of dirac deltas accumulating at 13.7. For the continuous spectrum, its flat for large energies. Is it still flat at the accumulation point? Or are there wiggles? Other systems behave as if the deltas widen into gaussians right at this point, and these sum up into a wiggly density. I honestly don't know what happens for the hydrogen atom.) I would expect the above questions to be handled in a review article; however, WP featured articles are written at a lower level and less stringent criteria than review articles, so the above comments shouldn't damage the FA status. (Review articles are typically 5-10 times longer than an FA could ever be, and aim at a target audience of professors and experts, rather than students. I have no clue if a review article for LRL has ever been written, ever.) 67.198.37.16 (talk) 16:26, 30 May 2021 (UTC)[reply]

A warm thank-you to the reviewers who have written so far! Re-reading the article, I was actually surprised at how good and thorough the article is and how well it's stood up over the past 14+ years: a tribute to the editors who worked on it so scrupulously. As the erstwhile "chief contributor", I am not at all opposed to improving the article further, but I'm also conscious of the warning: primum non nocere. Here are my suggestions for what I can do:
- I will seek out additional references to supplement the 50 citations already present. I noticed a few gaps right away, e.g., in the Context section, the remarks concerning conserved quantities in central-force problems and their relationship with symmetries. Well-known to advanced undergraduates, but worthy of citation. I currently don't have access to a university library, however, so I would be grateful for help in finding citations, esp. from colleagues at WP:Physics.
- The duplinks and the intra-article reference can be eliminated.
- I'm sympathetic to arguments that the level of the article is too low or too high. Most will agree that it's difficult to elucidate such an (admittedly abstract) topic both accessibly and encyclopedically. (As Einstein puts it, Die Natur verbirgt ihr Geheimnis durch die Erhabenheit ihres Wesens, aber nicht durch List.) That's why, through the efforts of many editors, the article was designed to have a "ramp-up" structure, beginning simpler and gradually increasing in complexity, as discussed on the article's Talk page, two peer reviews, and FA candidacy. It was a delicate balance to strike, and I'm loath to tinker with the clockwork. I was happy to read XOR'easter's assessment that the article was well-suited for advanced undergraduates, since that was admittedly my target audience. (They seemed to me the most likely to profit from such an article.) Regarding the level and content of the article, I was also heartened by the praise of John Baez, which appeared roughly a year after this article became an FA and which could provide excellent source material to augment the article.
- Additional applications and/or deeper connections of the LRL-vector could be added with citations, but a practical alternative might be to start a daughter article.
- If there are other outstanding issues, I would ask Extraordinary Writ to list those in detail, so that we can set to work! :)

Warm regards to one and all, Willow (talk) 08:07, 31 May 2021 (UTC)[reply]

Glad you're still around! I think the flow of the article is fine (well, I only skimmed it, it seemed fine from a skim.) The penultimate paragraph from the Baez pdf should be inserted into this article, as it unlocks the "geometric insight" for why it is what it is. Although I'm still confused about the Z_2 which John does not seem to mention. The reason I'm picking on this is that eventually one sees other examples of Poisson manifolds, and its useful to compare those examples at that particular abstraction level. That particular level of abstraction was the launch-pad/foundation of mathematical physics, 1980's-onwards, when familiarity with all the geometry (e.g. instantons and Witten and Wess Zumino type stuff) became de rigeur in the theoretical physics world. This example sets you up on that launching pad. p.s. the history is very much appreciated. History is interesting. 67.198.37.16 (talk) 03:22, 1 June 2021 (UTC)[reply]

ZOMG!!! How lovely to talk with you again; I feel as if I bumped into an old friend at a costume party. :) Do you realize that today is the exact 3×5=15th anniversary of the first time we spoke? What a wonderful coincidence. Anyway, I'm plugging away at improving the article and thank you so much for your suggestions! I'm fond of history, too, and I'm glad you're still here. Willow (talk) 16:58, 1 June 2021 (UTC)[reply]

Close without FARC. There's been a lot of work on this article since I started the FAR, and I'm glad to say that all my concerns have been addressed. A number of references have been added, and most of the places without citations can probably be justified as being, for purposes of this article, uncontroversial. The remaining issues that I pointed out have either been resolved or convincingly determined not to be issues at all. Thanks to all (particularly WillowW – I'm glad to see that you're back in the saddle) for your work on getting this article spruced up. Cheers, Extraordinary Writ (talk) 22:36, 2 June 2021 (UTC)[reply]

Thank you, Extraordinary Writ and everyone else who's been contributing! For my part, I'll continue to augment the article — hopefully without damaging it — since I daresay it's not yet as good as it could be; all are welcome to join in. :) Willow (talk) 05:38, 3 June 2021 (UTC)[reply]

@Hog Farm: what issues are outstanding here from your perspective? Nikkimaria (talk) 01:17, 19 June 2021 (UTC)[reply]
- @Nikkimaria: - I'm having a lot of trouble trying to assess this. To be completely honest, I just simply am several rungs in math education below where this concept is levelled. I see above that this is likely something in a graduate-level physics course, and while I have a bachelor's degree its in accounting and I've learned nothing even close to this. I can tell you that there's a source (Hall) in the further reading that is used multiple times and needs formatted as a ref, and that the non-English sources should probably state what language they're in. I just don't understand the article well enough beyond that, and don't feel confident even trying to comment on most of this article. Hog Farm _Talk 03:47, 19 June 2021 (UTC)[reply]
Close without FARC - it's been over a month since this was opened, the FAR nominator states their concerns have been addressed, and no other major concerns have been brought up since. I can't assess the content well, but with no issues really outstanding and enough time for anything to be brought up, this is probably fine. Hog Farm _Talk 22:17, 3 July 2021 (UTC)[reply]
Closing note: This removal candidate has been kept, but there may be a delay in bot processing of the close. Please leave the {{featured article review}} template in place on the talk page until the bot goes through. Nikkimaria (talk) 03:33, 5 July 2021 (UTC)[reply]

The above discussion is preserved as an archive. Please do not modify it. No further edits should be made to this page.