Talk:Quantum mechanics

Did you know nomination

The following is an archived discussion of the DYK nomination of the article below. Please do not modify this page. Subsequent comments should be made on the appropriate discussion page (such as this nomination's talk page, the article's talk page or Wikipedia talk:Did you know), unless there is consensus to re-open the discussion at this page. No further edits should be made to this page.

The result was: promoted by SL93 (talk) 02:17, 10 April 2021 (UTC)

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• ... that the principles of quantum mechanics have been demonstrated to hold for complex molecules with thousands of atoms? Source: "... we report interference of a molecular library of functionalized oligoporphyrins with masses beyond 25,000 Da and consisting of up to 2,000 atoms, by far the heaviest objects shown to exhibit matter-wave interference to date. We demonstrate quantum superposition of these massive particles by measuring interference fringes..." ([1])

Improved to Good Article status by XOR'easter (talk) and Tercer (talk). Nominated by Tercer (talk) at 13:30, 23 March 2021 (UTC).

• New GA, promoted 22 March (2 days ago), plenty long enough, and meets policy (except for the last sentence in history - more modern history than 1930 is needed, but in a bit more detail and with references! And there are some other unreferenced bits that could do with improving in the future, e.g., at the end of the mathematical formulation first part, but I don't think that's needed for this). Hook is referenced, and is interesting - although possibly there are more interesting hooks you could pull out of the article. No QPQ needed (1st DYK). The big problem, though, is that the article was on the main page as a Featured Article in 2004, I need to double-check with others that this is allowed. Thanks. Mike Peel (talk) 18:52, 24 March 2021 (UTC)
  • Asked at Wikipedia_talk:Did_you_know#DYK_that_was_formerly_Today's_Featured_Article?. Thanks. Mike Peel (talk) 18:58, 24 March 2021 (UTC)
  • If you have other suggestions for the hook I'd be happy to hear. As for the history, yeah, it should be expanded. One should be careful not to confuse it with quantum field theory, QED, QCD, etc., but there were plenty of interesting developments on the basic non-relativistic quantum mechanics. Tercer (talk) 19:33, 24 March 2021 (UTC)
    • @Tercer: It's up to you to suggest alt hooks if you want. No problems with the history needing to be expanded, but that paragraph (and probably the others) should be referenced - looking again at Wikipedia:Did you know/Reviewing guide it says 'A rule of thumb for DYK is a minimum of one citation per paragraph, possibly excluding the introduction, plot summaries, and paragraphs which summarize information that's cited elsewhere.'. Thanks. Mike Peel (talk) 19:56, 24 March 2021 (UTC)
      • I'm not going to start randomly inlining citations because of some arbitrary rule from DYK. The article is well-sourced. I removed this particular paragraph in any case, as that subject was better covered elsewhere in the article. Tercer (talk) 23:00, 24 March 2021 (UTC)
        • @Tercer: Thanks for removing the paragraph, but I hope it can be added back later with much more info. It's generally a good idea to include inline cites - if it was a paper introduction then they would be expected, it's not an arbitrary rule for DYK. So now, the main issue is whether this is OK given the past FA appearance - I expect it is, but let's wait a little to see what others think. Thanks. Mike Peel (talk) 23:11, 24 March 2021 (UTC)
          • @Tercer: Seems to be OK per the discussion at Wikipedia talk:Did you know. Thanks. Mike Peel (talk) 17:35, 25 March 2021 (UTC)
            • Great, thanks for letting me know. Tercer (talk) 17:39, 25 March 2021 (UTC)

We need a section shortly after the lead

We need a section shortly after the lead titled something like "Quantum Systems" that defines what a quantum system is and goes into detail about the different types of quantum systems. I'm an IP editor so I can't edit the article.

The impetus for this is: There are many articles in Wikipedia which mention the term "quantum system" or "quantum mechanical system"; Like for example: https://en.wikipedia.org/wiki/Spontaneous_emission . I was reading that article and I wanted to know what a quantum mechanical system is. It is even linked in the article. So I followed the link and I get to the page for quantum mechanics, which explains the field of physics but does not readily define what a quantum system or quantum mechanical system is.

So in short, this article needs a section that goes over what a quantum mechanical system is, including the different types of common systems like molecule, atom, subatomic particle, and potentially many particle systems.

Something like the following:

== Quantum Systems == A quantum system is a physical system that can be analyzed using quantum mechanics. Quantum systems are fundamentally irreducible, in that to analyze the system one needs to know the total state of the system to make any useful observation on it. In contrast, an [[open quantum system]] is one where not all the information about the system need to be known to be able to make a useful analysis. Examples of quantum systems include: * [[atom]]s * molecules * subatomic particles * other many particle systems Mathematically, a quantum system is the [[tensor product]] of its component systems.<ref>https://www.sciencedirect.com/topics/engineering/quantum-system</ref> — Preceding unsigned comment added by 96.227.223.203 (talk • contribs)

Quantization in Bound states

Hello. This is regarding a minor edit that was recently reverted.

'Quantum mechanics differs from classical physics in that energy,..., bound states are restricted to discrete values(of energy,...)' which had a change of 'are' to 'can be' since Bound states may not necessarily have discrete energy, for example.

@Johnjbarton Let's put our arguments and wait to see what others think. I think the article can remain as 'can be' to avoid inaccuracy in the meanwhile. EditingPencil (talk) 16:38, 16 December 2023 (UTC)

"Bound state" is probably a sufficiently esoteric term that the intro should avoid it, if possible. XOR'easter (talk) 16:48, 16 December 2023 (UTC)

First: the entire subject of "bound states in the continuum" is too advanced for this article. As you say these things don't have discrete energy. (IMO these things have been given unimaginative names).

But the reason I reverted your change has to do with the "differs from classical physics". These exotica are also classical. The point of the paragraph is to point out differences and the bound states of QM systems have discrete energy values whereas the bound states (orbits) of classical systems do not.

The discrete energy levels of QM systems is a distinction essential to the character of the theory. Johnjbarton (talk) 16:56, 16 December 2023 (UTC)

imho, it still conveys that point. I guess we can worry about re-wording it if more people share this issue.

Since I don't disagree with you, I don't mind if it were edited to include both facts. I guess, the introduction section should be simple to read though. EditingPencil (talk) 17:08, 16 December 2023 (UTC)

I rewrote the sentence entirely to focus on quantization. Johnjbarton (talk) 17:26, 16 December 2023 (UTC)

I think the wording is fine, but I still think it's better to use the weaker form of the sentence. If this thread finds more support for the later, we should change it. EditingPencil (talk) 18:23, 16 December 2023 (UTC)

Weaker? What would you propose? Johnjbarton (talk) 19:31, 16 December 2023 (UTC)

Maybe something like 'can have' instead of 'have'? I guess it's too pedantic so, I think I will leave this. EditingPencil (talk) 19:55, 16 December 2023 (UTC)

"Quantum realm" listed at Redirects for discussion

The redirect Quantum realm has been listed at redirects for discussion to determine whether its use and function meets the redirect guidelines. Readers of this page are welcome to comment on this redirect at Wikipedia:Redirects for discussion/Log/2024 April 25 § Quantum realm until a consensus is reached. Utopes _{(talk / cont)} 00:25, 25 April 2024 (UTC)

Understanding QT

Isn't physical quanta just really waves or wave packets? All that's need to resolve quantum mechanics issues is a deep understanding of waves. All physical realities or empirical observations can be explained by quantum waves. Getting rid of the idea of quantum particles as a physical reality would end much confusion in physics. Any "particle like" illusions or quanta can be explained by scientific explanations such as harmonic convergence of waves and the physical collapse of waves due to physical measurements. A paradigm shift in physics is needed. Having so many interpretations for QT taken seriously demonstrates QT is totally incomplete at best. It is also wrong about quanta being particles. Right now QT explains nothing about physical reality! Copehagen is just a fancy way of saying "I don't know" and Many worlds is, at best, a bad scifi idea. Mathematical consistency proves nothing about the truth and validity of a theory. It’s supposed to be Quantum wave theory not “particle physics”. 2601:601:702:B020:5D9C:97CA:FB55:DAC4 (talk) 17:08, 2 September 2024 (UTC)