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)

Semi-protected edit request on 14 July 2022

The elementary term for this field of science, object is not linked. I would change it to the correct terminology: "physical object" and include a link to its Wikipedia article here: https://en.wikipedia.org/wiki/Physical_object#Quantum_mechanics for those that have a limited knowledge of an object like I did. When I tried to find the definition I got this: Something perceptible by one or more of the senses, especially by vision or touch; a material thing. A focus of attention, feeling, thought, or action. A limiting factor that must be considered. This is in contrast to Quantum Mechanics. Our senses cannot detect Quantum objects. So what are they defined as? Quaantum Mechanics Vocab: In quantum mechanics an object is a particle or collection of particles. Until measured, a particle does not have a physical position. A particle is defined by a probability distribution of finding the particle at a particular position. There is a limit to the accuracy with which the position and velocity may be measured. A particle or collection of particles is described by a quantum state.

These ideas vary from the common usage understanding of what an object is.

String theory In particle physics, there is a debate as to whether some elementary particles are not bodies, but are points without extension in physical space within spacetime, or are always extended in at least one dimension of space as in string theory or M theory. A marked difference and major requirement for understanding the entire first paragraph.

IMPORTANT I put "quantity" in bold so many times to show that "qualities" is so overlooked part of Quantum Mechanics as is overlooked here. Yet the first paragraph states that Quantum means "the description of the physical properties". This is not quite right. The etymology of quantum is translated from latin to "how much", or, an amount. Therefore the name Quantum mechanics was chosen as it deals with numbers. But numbers, math, is a language that allow us to easily describe the properties of and how physical things work.

The phrase "and other quantities" should be changed to quantities that are known. This seems to have been written by someone either lazy or has incomplete knowledge. I do not know what quantitative elements are known in quantum mechanics. So, if there are "other quantities" that are referred as such, because they are known to exist but have no name, then explain this better. If there are other other quantities that are not listed, then why are these "other quantities" not listed? This is how it should be written: "...energy, momentum, angular momentum, new_entry, and final_entry quantities". Move the term quantization here as it makes more logical sense to have it next to quantum mechanic's quantities. Both quality and quantity should be part of this paragraph, together. Add link to the article defining "qualitative". Make sure to write a quick sentence that qualitative (here: https://en.wikipedia.org/wiki/Qualitative_property) is a close and important term that has been overlooked and will expand the total knowledge on what is being talked about, especially in this paragraph. This is where quantities are used to show the qualities. We see long, crazy equations and it looks alien and super hard. But it is actually very simple. The idea behind it is revvolutionary, but the math is actually an elegant, simple description. This is also true for Newtownian physics; see: https://en.wikipedia.org/wiki/Philosophi%C3%A6_Naturalis_Principia_Mathematica

I agree that the first part may need a rewrite. Here is an idea, everyone write to Neil DeGrasse Tyson to write it. I know, he is an astrophysist, but one of the best people on earth to get anybody to understand and enjoy: https://www.haydenplanetarium.org/tyson/contact.php I only ask this because Wikipedia has is ups and downs. Having people get the best writers to contribute will be worth more than gold.

Thanks, all. (Sorry for all the editing. I'm rusty to using this platform.) Austemagne (talk) 15:25, 14 July 2022 (UTC)

 Not done I don't see how linking to the short, choppy, and unsourced text at Physical_object#Quantum_mechanics would be anything more than a distraction. XOR'easter (talk) 16:08, 14 July 2022 (UTC)

@Austemagne: Thanks for your overview of the article with fresh eyes, and your perceptive comments. My feeling is that the changes you suggest would not be an improvement. The introduction is difficult to write because it is supposed to be understandable by general readers (WP:MTAU, WP:EXPLAINLEAD) but also an accurate summary of a very technical subject (MOS:INTRO))

• The emphasis on “quantities” as opposed to “qualities” is appropriate because QM is a quantitative theory. The main difference between quantum and classical physics is limitations on the ability to measure quantities.
• Linking “object” is unnecessary. It is being used in a descriptive rather than a formal sense
• Mentioning string theory in the intro is unnecessary and WP:undue weight
• I would welcome Neil DeGrasse Tyson contributing to the article

--Chetvorno^TALK 19:03, 14 July 2022 (UTC)

link needs updating

Hi -- I'm happy that the article links to my book The Modern Revolution in Physics under "External links." However, the more up-to-date version of the book would be Modern Physics, which is at this URL: http://www.lightandmatter.com/mod/ . I would update the link myself, but the article is locked. Thanks! -Ben Crowell — Preceding unsigned comment added by 2603:8000:8900:6E00:F161:CB6C:7FF:AB1C (talk) 00:55, 5 February 2023 (UTC)

Another citation is needed

@Logic314: Another citation is needed. Cannot use the Bell citation by itself to back the claim of nonlocality. We would need another source. It's possible to cite other sources. -- Ancheta Wis   (talk | contribs) 08:51, 20 May 2023 (UTC)

I don't think we need to say more about Bell's theorem in this article than we already do. XOR'easter (talk) 16:25, 20 May 2023 (UTC)

If you are not aware that Bell's Theorem does indeed prove nonlocality for tiny-scale quantum mechanics, I suggest you do some research on the Web to learn about it for yourself. There are many misconceptions about QM in circulation, and it is not a burden on WP editors to prove facts to other editors. David Spector (talk) 13:44, 9 August 2023 (UTC)

Hilbert's contribution

My problem is with the following:

"By 1930 quantum mechanics had been further unified and formalized by David Hilbert, Paul Dirac and John von Neumann with greater emphasis on measurement, the statistical nature of our knowledge of reality, and philosophical speculation about the 'observer'."

The single citation given for this sentence only emphasises von Neumann's contributions. While this work was based on the mathematics of Hilbert (i.e. Hilbert spaces), I have not found any sources to back up the claim that Hilbert himself was key to developing quantum mechanics during its later stages.

Proposal: remove Hilbert's name from this sentence (unless a reference can be found to support up this claim). Instead add something about the importance of his earlier mathematical innovations. 138.38.94.186 (talk) 11:24, 15 June 2023 (UTC)

Hilbert's contributions were abstract and influenced the physicists. The respect and esteem with which Born (and other close associates like v.Neumann) held Hilbert comes to mind, but Born's formulation of inner product for QM (B. formulated it in the 1920s) wasn't rewarded until 1955. Perhaps Hilbert's influence on Born and von Neumann might be the subject for an appropriate citation (from a historian of science). Or perhaps some parentheses, such as 'By 1930 quantum mechanics had been further unified and formalized by Max Born, Paul Dirac and John von Neumann (who were themselves influenced by David Hilbert)'.

I forgot Schwarz inequality. But this goes outside QM. There are other applications. (Think Signal processing in electrical engineering) --Ancheta Wis   (talk | contribs) 16:20, 15 June 2023 (UTC)

Hilbert contributed the mechanism that makes reasoning about measurements in the tiny scale easier, so I'd rather his name be retained. But it is also true that he was not one of the principal developers of QM. David Spector (talk) 13:48, 9 August 2023 (UTC)

Superdeterminism?

https://en.wikipedia.org/wiki/User:Proshno has been attempting to edit this article to claim that local realism may still obtain in quantum mechanics. However, this unusual claim is not backed up with any reliable references. This edit (https://en.wikipedia.org/w/index.php?title=Quantum_mechanics&diff=next&oldid=1169333352) cannot be allowed, per WP policies. Let's discuss here instead of edit-warring. David Spector (talk) 13:41, 9 August 2023 (UTC)

Superdeterminism, which Proshno was adding, is a theory that would explain quantum mechanics' violation of Bell's inequality without giving up locality:

• Knox, Wilson, The Routlege Companion to Philosophy in Physics p.190
• "...Bell nonlocality can be demonstrated as soon as the processes that choose the inputs and those chosen by the players are independent. The strongest way to deny this measurement independence is superdeterminism..." Scarani, Bell Nonlocality, p.20
• Bertleman, Zeilinger, Quantum (Un)speakables: Half a century of Bell's theorem, p.135
• "...in order for our discussion to be complete, it is necessary to mention an argument [superdeterminism] some have advanced for the purpose of avoiding the nonlocality condition. However... the proposed idea is not only artificial, but also quite radical and unwarranted" Hemick, Shakur, Bell's theorem and Quantum Realism, p.54
• "By proposing that the theory underlying quantum mechanics be both local and deterministic, superdeterminism removes both fundamental incompatibilities at once..." Adlam, Foundations of Quantum Mechanics, p.17

However I'm not sure it has sufficient support among physicists to merit Proshno's statement. --Chetvorno^TALK 18:52, 9 August 2023 (UTC)

I think it's okay for WP to mention the frontiers of thinking about QM, in the proper context. But in the context of a basic article about QM, I don't think that all conjectures need to be included. Certainly all major theorems and facts need to be included. Nonlocality, along with quantization, linear superposition, and wave/particle duality, is at the basis of QM. It is these basics that need to be in this article. Let's put the conjectures and ontological interpretations in a small section, with a link to an article that focuses just on them.

Our commonsense intuition, which validates local realism, is certainly valid in large scales, all the way up. But it is just as certainly misleading when applied to the very tiniest of scales. Let's maintain balance, and explain what has actually been discovered about QM, both experimentally and theoretically, and leave the interpretations and conjectures for another article. Otherwise, we run a serious risk of misleading those wishing to learn what is really known about QM. David Spector (talk) 19:40, 9 August 2023 (UTC)