Wikipedia talk:WikiProject Physics

WikiProject Physics
WikiProject Physics Main / Talk	Members	Quality Control (talk)	Welcome

Request to merge "megasonic cleaning" into "ultrasonic cleaning"?

I recently joined Wikipedia and my first suggested edit was to Megasonic cleaning. My guess is that this article would belong better as a subsection of the article on Ultrasonic cleaning. The help article Help:Introduction_to_talk_pages/All suggested that I draw some attention to it, since the article is a bit obscure.

RfC on states at Fermi level is equivalent to metallic conduction (and vica versa)

Are states at Fermi level equivalent to metallic conduction (and vica versa)?

Sandbh is claiming that they are not equivalent, and that similarly the opposite of having no states at the Fermi level is not equivalent to a non-metal (i.e. insulator/semiconductor etc) which does not conduct electricity, creating an edit war. This is in both Nonmetallic materials and Metals. The sources quoted are Ashcroft and Mermin and Kittel, the relevant chapters as (obviously) the Fermi-Dirac statistics and conduction is more complex than one sentence. It seems that Sandbh considers anything that is a paraphrasing as WP:OR, only direct quotes can be used. Unfortunately Sandbh appears to never have had any training in solid state physics. I am posting the RfC here as it covers more than one page and this is the most obvious place for it, particularly in light of his previous question here. Ldm1954 (talk) 14:39, 29 June 2024 (UTC)

Addendum, for simplicity you may want to just vote Equivalent or Not Equivalent with a little justification, similar to WP:AfD. Ldm1954 (talk) 14:41, 29 June 2024 (UTC)

No, I'm not claiming they are not equivalent.

Rather, I'm saying that neither Ashcroft, nor Mermin and Kittel, write what Ldm1954 is including in Nonmetallic materials and Metal. Here are the extracts from the the two articles:

Metal: "These properties are all associated with having electrons available at the Fermi level, as against nonmetallic materials which do not."

Nonmetallic materials and Metals: "A nonmetal has a gap in the energy levels of the electrons at the Fermi level."

Neither Ashcroft, nor Mermin and Kittel, refer to nonmetallic materials, or nonmetals in these terms. I've asked Ldm1954 for specific page numbers but he has has not provided any. Both sources do however refer to metals in the terms mentioned in the article, and that is fine. My concern here is not about metals, but rather about nonmetals.

No, I don't consider anything that is a paraphrasing as WP:OR. Paraphrasing occurs widely throughout WP as legitmate form of expression.

What is WP:OR is adding content to articles, whether in quotes or in paraphrased form, that is not explicitly mentioned in those sources. That is what going on here.

As WP:OR states (emphasis added):

"The only way you can show that your edit is not original research is to cite a reliable published source that contains the same material. Even with well-sourced material, if you use it out of context, or to reach or imply a conclusion not directly and explicitly supported by the source, you are engaging in original research; see below.

Yes, I've never have had any training in solid state physics. So I ask lots of questions and do a lot of research.

--- Sandbh (talk) 07:39, 30 June 2024 (UTC)

This explains it

Not sure what you mean by "states at Fermi level", but if the Fermi level is within a band, you have a metal. If it's outside of a band, you have either a semiconductor or an insulator, i.e. a non-metal. See diagram on the right. Headbomb {t · c · p · b} 17:46, 29 June 2024 (UTC)

Thanks. You phrased it slightly differently, but what you say is equivalent to states at E_f and the diagram. I will take this as an Equivalent vote Ldm1954 (talk) 18:17, 29 June 2024 (UTC)

Equivalent, I suppose. I agree with Headbomb that "states at a Fermi level" is...curious phrasing, but certainly if the Fermi level is within an energy band, then it's a metal, and outside of a band, depending on the band gap/position of the Fermi level relative to bands/etc you have a semiconductor or insulator. I believe Simon's Oxford Solid State Physics has a perhaps more succinct and readable section that may be easier to cite to someone who has less background in the field? I will note that the idea of the Fermi level shows up in more areas than just solid state physics so maybe this is part of the origin of the confusion? (Other references that may be useful are Blundell & Blundell, Schroeder's Thermal Physics, etc.) --Nerd1a4i (they/them) (talk) 23:26, 29 June 2024 (UTC)

All (what we call) metals have a nonvanishing density of states at the FL and exhibit so-called metallic conduction. Some materials that are semiconductors in the bulk do have a nonvanishing density of states at their surface and do conduct at 0 K. Some materials with a low density of states near the FL can be brought into a metallic conduction-regime by gating or chemical doping, but the fact does not make them metals in everyday sense. Some materials are gapped at the FL for the "supermobile" fraction of their charges, but the fact does not make them semiconductors at 0 K. All-in-all: it's equivalent, with some caveats for those who want to know more. Ponor (talk) 23:52, 29 June 2024 (UTC)

Extended states are needed for conduction. Xxanthippe (talk) 01:06, 30 June 2024 (UTC).

Coulomb "constant"

As far as I am able to determine, Wikipedia has invented the "Coulomb constant". There is a redirect for the term that points to Coulomb's law. I've changed that page to get rid of the invented term. Just to be sure, I checked sources like J.D. Jackson, R. Feynman, Panofsky and Phillips, and Purcell's Berkeley Physics E&M. They all discuss this factor in Coulomb's law as a proportionality constant or just as a convention for units.

So questions

• Should the redirect Coulomb constant be deleted?
  • I guess no, as I understand this can cause issues with links.
• Should there be something explicit about this non-thing?
  • Maybe add more about the units issue (I can source it per above). But I don't want go down the cgs/rmks rabbit hole.
• Other input?

Johnjbarton (talk) 03:21, 23 July 2024 (UTC)

I did find one source that uses the term:

• Deza, M. M., Deza, E. (2014). Encyclopedia of Distances. Germany: Springer Berlin Heidelberg.

But that source has it under a list of "physical constants" which is just incorrect. Johnjbarton (talk) 03:39, 23 July 2024 (UTC)

It does not seem to be purely a Wikipedia thing: see Ngram, and this this pre-2000 Google Books search which returns few hits. The usage seems rare enough that it does not necessarily need to be named, but giving the name might be the most stable solution, since IPs and other editors users will for sure restore the name from time to time. Jähmefyysikko (talk) 04:06, 23 July 2024 (UTC)

Usage is extremely widespread. High school and university students will encounter $F=k{\frac {q_{1}q_{2}}{r^{2}}}$ well before they see the $F={\frac {1}{4\pi \varepsilon _{0}}}{\frac {q_{1}q_{2}}{r^{2}}}$ version of Coulomb's law, and k is called either the 'electric force constant' or 'Coulomb's constant' in those context. Headbomb {t · c · p · b} 09:00, 23 July 2024 (UTC)

They may see this on the internet along with many other things. I have four authoritative sources which do not use the term "Coulomb's constant". Johnjbarton (talk) 14:52, 23 July 2024 (UTC)

It has several names (electric force constant, electrostatic constant, Coulomb force constant, ...). Here's about 4000 books that call k the Coulomb constant.

More advanced texts like Jackson prefer to work with closer-to-the-metal concepts, and use ${\frac {1}{4\pi \varepsilon _{0}}}$ instead of k and just don't need a name for that specific clump of variables. Headbomb {t · c · p · b} 18:10, 23 July 2024 (UTC)

Ok sorry I missed this post. I see there are plenty of other refs. Johnjbarton (talk) 03:46, 24 July 2024 (UTC)

@Jähmefyysikko Of course you can find it on the internet. But I was looking at reliable sources. Why would me make an exception for this case? Johnjbarton (talk) 14:54, 23 July 2024 (UTC)

No, nothing was invented there. That's how they teach the law in primary and secondary ed (at least in some countries). It's the analog of the gravitational constant, and how you express the qQ and 1/d² law without knowing the full theory of electromagnetism.

Britannica has it

Ponor (talk) 07:42, 23 July 2024 (UTC)

As for the constant name itself (in English alone):

[1] [2] [3] [4] etc. Ponor (talk) 08:03, 23 July 2024 (UTC)

I've restored mention that this is called the Coulomb constant. This is absolutely critical information to mention. Headbomb {t · c · p · b} 08:45, 23 July 2024 (UTC)

@Ponor Thanks, but these are all web sites, unreviewed and not authoritative sources. Johnjbarton (talk) 14:48, 23 July 2024 (UTC)

@Johnjbarton: I'm saying the redirect should not be deleted because the name is already out there and people will search for it. I did find the sentence "where k_e is a constant called the Coulomb constant" in my Serway and Jewett: Physics For Scientists and Engineers 6th ed, p 711 + pp 720, 728, Index, and table of "Some physical constants". I do not have any high school books in English. As for Britannica: at first I though you were disputing any use of k_e (as I saw some diffs for Coulomb law), my mistake! Ponor (talk) 15:27, 23 July 2024 (UTC)

I put the ninth Edition of Serway as a reference in the article. Standard 1000-level university textbook. Headbomb {t · c · p · b} 18:12, 23 July 2024 (UTC)

@Ponor Thanks. Please read the Britannia source carefully. It never says "Coulomb's constant". It says the same thing as my sources:

• "Expressed in the form of an equation, this relation, called Coulomb’s law, may be written by including the proportionality factor k as F = kq1q2/r2."

Johnjbarton (talk) 14:50, 23 July 2024 (UTC)

Surely this is a case where there is ambiguity, so the WP:NPOV is to be inclusive. I suggest that where k is mentioned we add "The proportionity constant k is sometimes called the Coulomb constant.[ref]" Perhaps even add an anchor and have the redirect go to the anchor. Ldm1954 (talk) 19:05, 23 July 2024 (UTC)

This is not ambiguous. There are other names, like the electric force constant, or Coulomb force constant, but if you ask any physicist what's the Coulomb constant, they'll all say ~8.99×10⁹ N.m²/C² Headbomb {t · c · p · b} 20:07, 23 July 2024 (UTC)

I have no vested interest in any of these names, but I do feel that we should be inclusive as encyclopedia editors. While I agree with your statement about "ask any physicist", we are writing for everyone, and in my opinion should try very hard to be discipline neutral. The fact that there is some debate here suggests to me that it is worth mentioning the other names -- what is an extra sentence between friends? Ldm1954 (talk) 21:07, 23 July 2024 (UTC)

@Headbomb Well that's the thing. I "asked" Feynman, Panofsky and Phillips, Purcell, and JS Jackson. They all agreed: Coulomb's law does not need a "Coulomb's constant". I tried The NIST site. I checked the Particle Data Group Physical Constants (a major revision). Zip.

We all form our opinions based on our experiences. You must have run in to textbooks that used the name, but this use is clearly far from standard or universal. Personally I had never seen or at least noted the symbol $k_{e}$ before a couple of weeks ago and never heard of thing called "Coulomb's constant". In my experience $k$ just stands for what ever constants are needed by the units in whatever formula is being discussed.

We have references that use this term and many notable ones that could, but do not. In my opinion this dichotomy should be discussed in the article. I will go ahead and make some changes and hopefully we can agree on some middle ground matching the sources. Johnjbarton (talk) 01:15, 24 July 2024 (UTC)

Coulomb's law does not need a "Coulomb's constant". Sure, in the same sense that you don't "need" Rydberg's constant, you have ${\frac {m_{\text{e}}e^{4}}{8\varepsilon _{0}^{2}h^{3}c}}$. You don't "need" the Bohr magneton, you have ${\frac {e\hbar }{2m_{\mathrm {e} }}}$. You don't need the Bohr radius, you have ${\frac {4\pi \varepsilon _{0}\hbar ^{2}}{e^{2}m_{\text{e}}}}$.

Headbomb {t · c · p · b} 01:34, 24 July 2024 (UTC)

Sorry, but your examples only provide additional evidence for my point of view.

The term "Rydberg's constant" appears in A. Pais book "Inward Bound" and Whittaker's Aether and Electricity history; it appears on the CODATA site. Similarly for the Bohr magneton. I'm sure I could find many more refs for these terms, these just happened to be on my desk today.

It is exactly this difference in the level of extensive, reliable sources that make these terms notable enough for a complete article. My same broad sources are mute on "Coulomb constant." This difference should be part of our article per WP:NPOV. Johnjbarton (talk) 02:18, 24 July 2024 (UTC)

I've linked to roughly 4000 books that call it the Coulomb constant. If you want one specifically, there's Serway. This is a standard 1000 level intro to EM university textbook. This is not WP:NPOV, this is basic physics terminology. Headbomb {t · c · p · b} 02:25, 24 July 2024 (UTC)

Reliable sources for the term have been presented. That is sufficient. The fact that some other sources happen not to mention it is irrelevant to the question of whether we should. --Srleffler (talk) 06:51, 28 July 2024 (UTC)

@Srleffler I guess you missed my post above the same way I missed @Headbomb's post with the refs earlier in the topic. Johnjbarton (talk) 23:50, 28 July 2024 (UTC)

Request for comment: presenting Rutherford's 1911 paper in Rutherford's way.

Please offer your opinion on this topic at Request_for_comment:_presenting_Rutherford's_1911_paper_in_Rutherford's_way. Thanks Johnjbarton (talk) 22:32, 28 July 2024 (UTC)

Klein's Paradox

Improvments in Visual Aids and Diagrams:

More illustrative diagrams to help explain the theoretical concepts and mathematical derivations. I believe that a more thorough and well-rounded article would be incredibly beneficial for students, researchers, and enthusiasts alike. If any of you have expertise in quantum mechanics or related fields, your contributions would be invaluable.

Thanks for your help! Bishopandknight (talk) 00:56, 3 August 2024 (UTC)

I guess you are referring to the Klein paradox article? I think it needs much more than a diagram. Johnjbarton (talk) 16:25, 3 August 2024 (UTC)

The whole article has to be rewritten, I do not think that even the equations are right.--ReyHahn (talk) 11:39, 5 August 2024 (UTC)

I found a good ref to start and will give it a try.

The topic is one-dimensional QM scattering from a step potential at relativistic velocity. So it's one step ;-) above simple QM, at the intersection with relativity, and is used in introductory quantum field theory examples. Seems interesting. Johnjbarton (talk) 00:24, 6 August 2024 (UTC)

de Broglie–Bohm theory vs Pilot wave theory

Are these two topics different things?

According to Pilot wave theory it describes de Broglie's original single particle theory, not the "modern" (ie 1950's) de Broglie–Bohm theory.

• If we go with this definition about half of the article needs to be deleted. Then it would make sense to merge into de Broglie–Bohm theory as a historical section.

According to de Broglie–Bohm theory it is "also known as the pilot wave theory".

• If we go with this we should merge.

Thus I come to merge. Maybe there is a ref somewhere that clearly sets these apart in the way we do not. WDYT? Johnjbarton (talk) 16:13, 6 August 2024 (UTC)

I do not know enough to know the difference. I wonder if a merge, and a name change into Bohmian mechanics would be better.--ReyHahn (talk) 17:37, 6 August 2024 (UTC)

Maybe you are on to something, the Ngram viewer for Pilot wave theory,Bohmian mechanics,de Broglie-Bohm theory,Bohm theory agrees. Johnjbarton (talk) 02:24, 7 August 2024 (UTC)

Quick merge: The Queries into Opticks

The Queries is a subsection of Book III, Part I of Isaac Newton's Opticks it makes no clear sense that it should be its own article. The (relevant) content of the Wikipedia article for The Queries is already in the Opticks one. Both unsourced. Should The Queries redirect to Opticks? ReyHahn (talk) 17:41, 13 August 2024 (UTC)

merge A clear win. Johnjbarton (talk) 18:39, 13 August 2024 (UTC)

Redirect to the Queries section in Opticks; merge seems to not be necessary as the content is already there. Sgubaldo (talk) 00:21, 14 August 2024 (UTC)

 Done.--ReyHahn (talk) 17:21, 14 August 2024 (UTC)

Template:Equation box 1 in Android dark mode

Some 390-ish articles like Dirac equation use a box around special equations. The implementation, Template:Equation box 1 failed on Android in the now-default dark mode. The box was just white. I removed the background-colour feature and the equations now appear. Extra text in the box is not visible, which suggests an issue with "color" but I'll leave that as a minor issue. Johnjbarton (talk) 18:14, 15 August 2024 (UTC)

Exception for WP:Toosoon and WP:SOURCES?

In this edit to Hubble's law @Banedon added content based on an unpublished and uncited ArXiv paper:

• Freedman, Wendy; et al. (12 August 2024). "Status Report on the Chicago-Carnegie Hubble Program (CCHP): Three Independent Astrophysical Determinations of the Hubble Constant Using the James Webb Space Telescope".

The claim added is very mild. Bandon has made the case in Talk:Hubble's law that this source should be allowed.

Since I routinely revert additions based on newly published papers let alone ArXiv preprints, I would like consensus on this exception. I would say the exception is based on the consortium of authors being a form of review, the YouTube video review, and the mild nature of the claim.

Please respond on Talk:Hubble's_law#Update_potentially_needed_for_Hubble_Tension_section?. Thanks.

(Posted to WikiProject physics and astronomy) Johnjbarton (talk) 15:09, 17 August 2024 (UTC)

Probability four-current

We need either and article or an article sub-section on the probability four-current. Previously, probability four-current was a redirect to a subsection of the probability current article that gave the relativistic definition, but that no longer exists.

There seems to be very little good material online about this, and I'm not a specialist in the field, so I'm not going to try to do it myself. At the moment, this tutorial is the simplest treatment I can find and (just about) understand. Can anyone more knowledgeable help? — The Anome (talk) 07:45, 19 August 2024 (UTC)

I think that a subsection in probability current or in four current would be enough.--ReyHahn (talk) 11:19, 19 August 2024 (UTC)

Yes, a subsection is better. Johnjbarton (talk) 15:36, 19 August 2024 (UTC)