Wikipedia talk:WikiProject Physics/Archive January 2021

Wave mechanics

Hi all, it came to my attention through edits of A History of the Theories of Aether and Electricity that wave mechanics is actually a DAB page that says that wave mechanics can refer to "the mechanics of waves" or the "wave equation in quantum physics, see Schrödinger equation". User Narky Blert fixed the link to the DAB page by linking to quantum mechanics, while user IAmNitpicking believes that is the wrong target. Currently none of these pages have a section dedicated to wave mechanics, which is rarely even mentioned in prose. So my question is, why is there no complement to our article on matrix mechanics and Path integral formulation and where should a link to wave mechanics actually point? I assume it is because wave mechanics is generally just called QM, like the last paragraph of that article, which reads: "The Schrödinger equation is not the only way to study quantum mechanical systems and make predictions. The other formulations of quantum mechanics include matrix mechanics, introduced by Werner Heisenberg, and the path integral formulation, developed chiefly by Richard Feynman...". With this, I am inclined to agree that QM is the correct target for wave mechanics, but it should be mentioned somewhere. Footlessmouse (talk) 22:44, 11 December 2020 (UTC)

Honestly, I did not realize that people were using "wave mechanics" to mean Schroedinger wave equation stuff. When I was a physics major back in the Dark Ages (the 1970s), I never heard that, and "wave mechanics" was about cyclical phenomena in general, e. g. water waves, harmonic oscillators. I think I might have been incorrect in my reversion. IAmNitpicking (talk) 00:34, 12 December 2020 (UTC)

It's definitely a term people have used for Schrödinger-wave-equation stuff, though my impression is that it's older and less common now. XOR'easter (talk) 00:51, 12 December 2020 (UTC)

Ok, that makes sense. Wave mechanics was used in the article only to juxtapose matrix mechanics and I don't really know of a better way to word it. I don't really remember using either of the terms often when learning the material, it was all just QM, but I've definitely heard it around. Thanks! Footlessmouse (talk) 01:08, 12 December 2020 (UTC)

Back in the even Darker Ages (1967-68), WM was more-or-less synonymous with QM; perhaps slightly broader, but still at the subatomic level (IIRC - J. W. Linnett was a terrible lecturer, and as an organic chemist I was only interested at the qualitative MO level). QM isn't an exact fit for what WM may have meant in 1951, but it seems to be the closest we've got. Narky Blert (talk) 06:23, 12 December 2020 (UTC)

On the other hand, I don't recall the physics of transverse or longitudinal waves being called wave mechanics, which was very much a C20 thing. Narky Blert (talk) 07:18, 12 December 2020 (UTC)

Thanks all! I have made changes to the article to fix the dab since everyone seems to agree. I also have never heard of "the mechanics of waves" being referred to as "wave mechanics" in a classical sense, I thought the DAB was strange, but I think that about a lot of our DAB pages and there is no real target. I don't know if it's possible, given how long the article is and the sheer amount of content that has been written about it, but I would like to try to improve it to FA status or as close as possible, so any help or suggestions would be greatly appreciated. Thanks again! Footlessmouse (talk) 07:30, 12 December 2020 (UTC)

I think everyone is right. My impression is that phrase "wave mechanics" was a popular from 1920'2-1960's and then faded into dis-use; during that period, it refers to the Schrodinger-related subset of QM. It might have lasted longer in the classroom, because intro-to-QM classes always talk about ripple tanks to demonstrate interference. Now that the phrase is effectively abandoned, I wouldn't be surprised if oceanographers have adopted it for their own use. I wouldn't be surprised, but have no idea if that's the case. Unfortunately terminology comes and goes, and I'm not clear on how WP plans to account for the changing fashions in what we call things. 67.198.37.16 (talk) 04:55, 23 December 2020 (UTC)

I agree with previous commenter. Also I remembered this. I have searched in INTERNET "Wave Mechanics" asking only for the images, getting wave mechanics in the title of books written by De Broglie (... interpretation of WM), Pauli (WM) and Schroedinger (Collected Papers in WM)Suppongoche (talk) 09:48, 2 January 2021 (UTC)

compton wavelength

This article contains

>>>>For fermions, the reduced Compton wavelength sets the cross-section of interactions.<<<< For example, the cross-section for Thomson scattering of a photon from an electron is equal to[clarification needed] .....

I feel it wrong (but I have not a regular training in physics). May anyone safely state if is simply right or simply wrong or right under suitable constraint?

 Suppongoche (talk) 17:00, 1 January 2021 (UTC)

It is correct. It is simply referring to the scale (like order of magnitude). The fine structure constant is a constant and so the scale is determined by the reduced Compton wavelength. Simply searching Google for the cross section of Thomson scattering will yield sources for the math formula (the citation needed there is probably unnecessary), and the statement preceding it is really a summary of the math formula. Many sources just write out the whole cross-section, but usually as (SI): $\sigma _{T}={\frac {8\pi }{3}}\left({\frac {e^{2}}{4\pi \epsilon _{0}mc^{2}}}\right)^{2}$ where ${\frac {1}{4\pi \epsilon _{0}}}{\frac {e^{2}}{{\bar {h}}c}}=\alpha$ and ${\frac {\bar {h}}{mc}}={\bar {\lambda }}_{\text{e}}$ so that $\alpha {\bar {\lambda }}_{\text{e}}={\frac {1}{4\pi \epsilon _{0}}}{\frac {e^{2}}{mc^{2}}}$. Some sources (CGS, like Jackson, p.695) will not include the ${\frac {1}{4\pi \epsilon _{0}}}$ bit. I hope this helps. Footlessmouse (talk) 11:32, 2 January 2021 (UTC)

I want to note that $\alpha {\bar {\lambda }}_{\text{e}}$ is just Classical electron radius. Ruslik_Zero 14:27, 2 January 2021 (UTC)

Dear @Footlessmouse:, as usual (also in my native italian) I am unable to make clear what I mean. First of all, thanks for the prompt answer and for the patience needed in talking with me.

The point is not the correctness of the Thompson formula, but of the phrase >>>For ... interaction<<<<. Who (not I) has added "clarification needed" has added it in the wrong place: it had to be added after "interaction" (i.e where I wrote <<<<), not at the end. This has contributed to attract your attention to a different problem.

What puzzled me was:

* why ONLY for fermions (immediately after >>>>)? Perhaps because the non-gauge bosons are treated as combinations of fermions?

* for which interaction (immediately before <<<)?. The example is for the electromagnetic one, but the phrase immediately below for the gauge bosons suggests all four.

Suppongoche (talk) 17:52, 2 January 2021 (UTC)

It is still correct. For your first question, bosons just aren't as pushy as fermions, as they don't behave any form of the Pauli exclusion principle. As for your second question, it is referring to electromagnetic interactions, but what else is there? Strong, weak, and gravity are the other "fundamental forces" and we don't typically study scattering interactions in those realms (except HEP, who do lots of simulations of strong force interactions, but it is a bit different). Think about it like this: as Ruslik pointed out, $\alpha {\bar {\lambda }}_{\text{e}}$ is the classical electron radius while the classical cross section is given by $4\pi r^{2}$. There is a difference of a constant between this classical answer and the actual cross section, but it captures its dependencies. Footlessmouse (talk) 18:59, 2 January 2021 (UTC)

Note: I didn't read all of that the first time. What's important, in EM interactions, is that the "radius" at which the electron "orbits" is proportional to the Compton wavelength and it sets the scale of interaction. Two neutral bosons will not interact with each other and only the W and Z bosons have charge and their half-lives are extraordinarily short, so I'm not sure whether or not it is even viable. The effect apparently also exists for Yukawa interactions (strong force), but I do not know any details on that. This is not really my field of expertise, I just chimed in because no one else answered and I am confident it is correct. Footlessmouse (talk) 23:02, 2 January 2021 (UTC)

Thanks. You have helped me in understanding the real problem: I have attempted to extend the statement beyond its scope (I wondered why it seemed to exclude the bosons -- e.g. deuterons and alpha particles -- from Thompson scattering). Suppongoche (talk) 07:32, 4 January 2021 (UTC)

Plot request: Norton's dome

Anybody with good graphics skills that wishes to at least do a plot of the edge of the Norton's dome (either 2D or 3D)? Equation in the article. --ReyHahn (talk) 15:09, 5 January 2021 (UTC)

Lol, no, the equation is not in the article. It gives h as a function of the arc length, what we need for plotting is h as a function of x. I hope I'm not too old for this, I solved it and got

$x(h)=-\left(\left({\frac {2}{3}}g^{2}\right)^{\frac {2}{3}}-h^{\frac {2}{3}}\right)^{\frac {3}{2}}+{\frac {2}{3}}g^{2}$

No wonder Norton preferred to use the arc length as a parameter! With this equation anybody can make the figures for you using plotting software. Note that the dome is finite, contrary to what I thought when reading the article: both x and h go from 0 to ${\frac {2}{3}}g^{2}$, and r goes from 0 to $g^{2}$. Tercer (talk) 19:20, 5 January 2021 (UTC)

Oh no you are right it is not y(x) but y(r) which makes it more complicated. I think there is something wrong there though, you have some powers that can simplify.. --ReyHahn (talk) 21:00, 5 January 2021 (UTC)

Sorry, my computer was not displaying it well, I get the same equation as you. You can invert it for x, here is a WolframAlpha plot for g=π: [1]--ReyHahn (talk) 21:33, 5 January 2021 (UTC)

Nice, good to know. Any particular reason for using g=π? I would set instead ${\frac {2}{3}}g^{2}=1$, so that instead of

$h(x)={\frac {2}{3}}g^{2}-\left(\left({\frac {2}{3}}g^{2}\right)^{\frac {2}{3}}-\left({\frac {2}{3}}g^{2}-x\right)^{\frac {2}{3}}\right)^{\frac {3}{2}}$

we get

$h(x)=1-\left(1-\left(1-x\right)^{\frac {2}{3}}\right)^{\frac {3}{2}}$

And here [2] is the dome. Tercer (talk) 22:01, 5 January 2021 (UTC)

It was done just to identify where g went, but 2g^2/3=1 is a good idea. Again, we just need somebody willing to plot it and upload it.--ReyHahn (talk) 08:34, 6 January 2021 (UTC)

Shouldn't it be revolved around y axis instead of x?--ReyHahn (talk) 09:33, 6 January 2021 (UTC)

Sure, the axis of revolution should be vertical. I don't really know how to use Wolfram Alpha. In any case, I added the plot there. I did the 2D version, not just out of laziness, but also because you don't really see the singularity at the summit in the 3D version, and the singularity is all that matters. Tercer (talk) 11:07, 6 January 2021 (UTC)

Quantum mechanics nominated for Good Article status

The article Quantum mechanics is now a Good Article nominee in the "physics and astronomy" category. Anyone who has not contributed significantly to (or nominated) this article may review it according to the good article criteria to decide whether or not to list it as a good article. The procedure for starting a review can be found at the top of Talk:Quantum mechanics. XOR'easter (talk) 15:27, 6 January 2021 (UTC)

Draft:Gurzadyan-Savvidy relaxation

Isthere any reason this draft should not be accepted? DGG ( talk ) 19:35, 6 January 2021 (UTC)

I can find only two publications where this phenomenon is actually called "Gurzadyan-Savvidy relaxation". It does not seem to be notable. Ruslik_Zero 20:39, 6 January 2021 (UTC)

should it be called something else? DGG ( talk ) 01:33, 9 January 2021 (UTC)

Reject. Insufficient evidence yet of notability. Xxanthippe (talk) 01:47, 9 January 2021 (UTC).

Coupled-wave method

Hello, found this while trawling through stubby orphans. Anyone have any idea whether it should remain standalone, or can it be merged somewhere (or even deleted?). I'm not good at evaluating physics-related topics so I'd appreciate any help I can get. ♠PMC♠ (talk) 01:03, 14 January 2021 (UTC)

This could be redirected to Rigorous coupled-wave analysis, as it is another name for this method.[3] --{{u|Mark viking}} {Talk} 01:40, 14 January 2021 (UTC)

Done, thank you. ♠PMC♠ (talk) 05:46, 17 January 2021 (UTC)

Contest proposal

While working on quantum mechanics, I got a bit shocked that the article was in such a bad state, even though it is extremely visible: it gets roughly 120k views per month! With the help of XOR'easter, I investigated a bit, and saw that the problem is rather widespread: of the 40 most visible articles in physics, only 4 have GOOD/FEATURED status. The reason is probably very simple: editors write about what they find interesting, and these are very often niche/obscure topics. At least that's what I do.

To remedy this, I suggest we do a contest, much like other WikiProjects often do. Make a list of articles that are important, very visible, and in a bad state, and offer prizes for editors that improve them. Usually these prizes are just peer-recognization in the form of a fancy barnstar, but to give an extra incentive for editors to work in not-necessarily-sexy topics, I'd be willing to put some of my money on it (e.g. offering 20€ per article that makes it into GA/FA status, up to a limit of 120€ in total).

What do you think? Can it work, or is it a terrible idea for some reason that I haven't thought of? Note that the Core Contest offered monetary rewards several times, so it's not against the rules. Also, anybody volunteers to help? I'd like help with judging the work, creating the list of articles to improve, and designing the fancy barnstar (my idea would be something like a barnstar of fennel on fire, alluding to Prometheus).

I do have a preliminary list of articles, together with the monthly page views:

1. Newton's laws of motion - 160,228
2. Temperature - 72,412
3. Electromagnetic radiation - 67,365
4. Light - 63,584
5. Proton - 46,971
6. State of matter - 45,106
7. Momentum - 44,899
8. Radioactive decay - 40,501
9. Mass - 39,237
10. Thermodynamics - 37,156
11. Neutron - 28,412
12. Standard Model - 25,686
13. Classical mechanics - 21,027
14. Particle physics - 17,366
15. Strong interaction - 17,313

Tercer (talk) 12:08, 13 January 2021 (UTC)

I can help judge. My graphic design skills probably aren't up to the task of making an evocative barnstar, though. XOR'easter (talk) 16:17, 13 January 2021 (UTC)

I really like this idea, many of our core topics are not in very good shape and it could potentially be very helpful have an organized effort to improve them. Editing highly visible articles is sometimes not very fun, requiring extensive discussion for minor changes, it quickly leads to burnout. Some sort of competition or reward system may just help encourage editors who otherwise would not want to deal with it all. Footlessmouse (talk) 19:31, 13 January 2021 (UTC)

Thanks for the feedback. I'll write it up more formally tomorrow. I think it would be good to start the contest very soon, since so many countries are in lockdown and people don't have much to do. Can we do it as a contest from the WikiProject Physics itself? I don't want to brand it as my personal idiosyncrasy. Also, does anybody know how can we advertise the existence of the contest? Here, presumably. Maybe also in the talk pages of the selected articles? Tercer (talk) 22:51, 14 January 2021 (UTC)

I've put up a draft in my sandbox. Tercer (talk) 23:14, 15 January 2021 (UTC)

Looks pretty good. Maybe the announcement should refer to Wikipedia:The Core Contest? Following the example of... Would it help to include in the announcement a few things we'd look for in an improvement, or would linking to the Good article criteria be enough of a hint? Maybe we should be more direct and say something like, "Claims should be sourced to well-regarded textbooks and review articles, rather than press releases and random websites." XOR'easter (talk) 16:48, 16 January 2021 (UTC)

Good point, I linked to the Core Contest, and also to WP:GA and WP:FA. I don't see the point of repeating the good article criteria there, we're not asking for anything different. Tercer (talk) 23:11, 16 January 2021 (UTC)

Looks good — thanks. XOR'easter (talk) 05:13, 17 January 2021 (UTC)

Excellent idea! -Dilaton (talk) 19:16, 16 January 2021 (UTC)

Thanks! Suggestions to the list are most welcome. Tercer (talk) 23:11, 16 January 2021 (UTC)

Inertia has 32,015 pageviews in the past 30 days. Maybe it should join the list? XOR'easter (talk) 05:35, 17 January 2021 (UTC)

Good one, added, thanks. Tercer (talk) 13:32, 17 January 2021 (UTC)

Wow, I just checked Quantum computing: 88,532 pageviews! Probably fueled by recurring pop-science hype. XOR'easter (talk) 18:47, 17 January 2021 (UTC)

We're not interested in the latest frenzy, but if the hype is recurring the topic is simply important. Added. Tercer (talk) 09:54, 18 January 2021 (UTC)

Contest is live

Thanks everybody for the positive feedback, the contest is now live. I boldly added it to the project main page as a part of the template, and left the contest itself as a subpage here. As before, suggestions on how to advertise it are most welcome. Tercer (talk) 11:40, 18 January 2021 (UTC)

Great! I'll post it over at WT:MATH, as there might be an overlap of interest. XOR'easter (talk) 16:54, 18 January 2021 (UTC)

Casimir effect

Opinions welcome at Talk:Casimir_effect#Energy_extraction?. XOR'easter (talk) 21:51, 18 January 2021 (UTC)

Should we have a constant in Norton's dome equation

Two users (myself included) disagree over how to define Norton's dome. In his original formula Norton's writes that height is $h=2r^{3/2}/(3g)$ where r is a distance and g is supposedly the acceleration due to gravity. Surely we can see that it is dimensionally inconsistent in SI units. The discussion is on how to display it on Wikipedia (add a constant, leave it as so, no constant,...), check it here Talk:Norton's dome#Constant, a third opinion would be nice to settle which version to use.--ReyHahn (talk) 13:59, 22 January 2021 (UTC)

New Article Notability question

I recently did a research project on dissociative electron attachment (DEA) and though several pages mention the process, there is not yet an article. The topic seems "notable" to me, but I wanted to get second opinions here before I started work on writing the article. I'm also new to editing wikipedia, so I'm not sure if it's a good idea to start right in on creating a new page. Does the topic seem like it warrants its own article? Karl.ahrendsen (talk) 15:27, 29 January 2021 (UTC)

The term goes back a long way and there's plenty of research published on it. Plus it has several mentions already in WP which could be considered to be wikilinks. So I'd say it is a pretty strong candidate. If this is your first article, you might want to consider the articles for creation process, although it can sometimes be slow to get feedback. Usually, it is best to make some not-too-huge edits on a few articles, perhaps related to DEA, and get the hang of it first. You might not even have the rights to create a new article until you've made a certain number of edits. Otherwise work in draft or your sandbox until you have something that isn't going to be deleted at first sight. Fair or not, a new article by a new editor will get especially close scrutiny. Make sure the sourcing is good enough to support the content in the article and to demonstrate notability. Also read WP:COI so you don't fall into any bear-traps. Lithopsian (talk) 15:40, 29 January 2021 (UTC)

Okay, thanks for the feedback. I'll get started on a draft and hopefully find a few other things things that I can contribute to in the meantime to build up my "reputation." Karl.ahrendsen (talk) 15:45, 30 January 2021 (UTC)

Hidden-variable theory

There are some problems with the Hidden-variable theory article. As it was written previously the lead stated that hidden-variable theories are all deterministic, which isn't exactly correct (though determinism should be mentioned). The most recent edit attempted to address that just by deleting the word "deterministic", but deleting this word now means the lead doesn't make much sense. Some help would be appreciated as I'm probably not the right person to rewrite all of it. (Also, extremely minor point but the article should probably be moved to hidden variable theories). Volteer1 (talk) 06:58, 31 January 2021 (UTC)

Regarding the last point: Wikipedia article titles are generally singular (See WP:SINGULAR).--Srleffler (talk) 22:07, 31 January 2021 (UTC)