Wikipedia talk:WikiProject Physics/Archive August 2024

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).

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)