Talk:Teaching quantum mechanics

Discussion on draft version

Prior to creating this page it was discussed here: Wikipedia_talk:WikiProject_Physics#Proposal_to_create_and_adopt_"Teaching_quantum_mechanics" Johnjbarton (talk) 00:56, 18 July 2023 (UTC)

Does the page represent what the references say or ?

@ReyHahn thanks for your recent edits. They seem to take the content in a direction I did not expect and one that concerns me. Should the content on this page reflect the references cited or something else? When it is something else should we include new references.

For a concrete example, the reference name "insights-review" used the term "quasi-quantum" and now it reads "semiclassical". I think that the authors of the paper cited intended "quasi-quantum" to be distinct from semiclassical. The students are making stuff up. The educators are classifying that make-believe, and one category they chose was "quasi-quantum". The students aren't applying "semiclassical" ideas, they are simply a bit mistaken. Johnjbarton (talk) 02:07, 18 July 2023 (UTC)

I have no problem reverting back to quasi-quantum but it is sometimes best to be precise. Do we have an exact definition "quasi-quantum"? The more common term would be semiclassical, which is well defined and leads to quantization schemes under some classical approximations.--ReyHahn (talk) 02:11, 18 July 2023 (UTC)

You're correct, I will include the definition from the reference.

What about the footnote on probability vs determinism being a Copenhagen thing? Do any mainstream interpretations claim results are deterministic? That is what the whole God-dice-Einstein thing was about. Johnjbarton (talk) 02:21, 18 July 2023 (UTC)

For that I will insist a bit more. Clearly mostly under Copenhagen interpretation (the most used one) it is very clear that QM is probabilistic. But all the effort of the other less-but-still popular interpretations like many worlds and pilot-wave/bohmian mechanics are deterministic (but weird in other ways).--ReyHahn (talk) 02:30, 18 July 2023 (UTC)

Could we add some reference to that effect? Things I've read go the other way, eg

• Hsu, Stephen DH. "On the origin of probability in quantum mechanics." Modern Physics Letters A 27.12 (2012): 1230014.
• https://www.quantamagazine.org/where-quantum-probability-comes-from-20190909/
• https://plato.stanford.edu/entries/qm-bohm/

At least it would seem to me that every QM theory would need to explain the random appearance of dots on the double slit screen. So students would need to know about that issue. Johnjbarton (talk) 02:46, 18 July 2023 (UTC)

Have you taken a look into Interpretations of quantum mechanics it is a recurring topic in these interpretations to discuss to what extent QM is "deterministic". From the quanta article that you cited "Pilot-wave theories tell a very different story. Here, nothing is truly random; the quantum state evolves deterministically" and " In many-worlds, we can know the wave function exactly, and it evolves deterministically. " From the Standford enciclopedia we have "Bohmian mechanics the configuration of a system of particles evolves via a deterministic motion choreographed by the wave function."--ReyHahn (talk) 02:56, 18 July 2023 (UTC)

Yes, but the question in the Teaching article concerns "results" not "evolution". "Evolution", like "trajectories" is not observable. The results are not deterministic: different interpretations of why the results are not deterministic exist. So the pilot wave theory proposes deterministic evolution but nevertheless probabilistic results. One might argue that student should be educated on the various ways that probability might be interpreted, but that would be after they are clear on the results I think.

So from the Quanta article "Probability in pilot-wave theories, in other words, is entirely subjective. It characterizes our knowledge, not an objective frequency of occurrences over time." (The Stanford philosophy article says as much in a lot more words ;-). The Stephen Hsu article claims to show how Born rule probabilities arise from Everett model.

I think the educators did a pretty good job of expressing QM ideas while not getting tangle up in interpretation issues. I'd like to do as well. Johnjbarton (talk) 03:18, 18 July 2023 (UTC)

I agree that when first teachings these subjects the best is to avoid interpretations, however the difficulty of teaching QM is that even trained physicist do not have a unique version of understanding it (maybe this should be said somewhere). Maybe a more relevant question is, why is the note a problem? Another possibility is to remove the point entirely, the important part here is not determinism is the "intrinsic uncertainty rather than measurement error" which is another bullet in the list.--ReyHahn (talk) 03:24, 18 July 2023 (UTC)

Also note that the Phys Rev Educ article also discusses the problem of interpretations.--ReyHahn (talk) 03:31, 18 July 2023 (UTC)

To me the note implies that "quantum mechanics gives probabilisitic rather than deterministic results" is not correct. The reference makes this particular claim and I think the statement is correct as is. If it were only correct under Copenhagen, then that should be said directly rather than in a footnote. Again this is about observations not interpretations.

I don't think we should remove the point because this issue is so critical and central to QM. It's not related to either intrinsic uncertainty nor to measurement error. All three items need to be discussed. But that is a question for our effort on the Introduction. Here the issue is whether it's a notable part of the referenced report.

The report is slim on "interpretations" and I only saw a mention of a study of using Copenhagen compared to no interpretation. That's why I didn't put it on the list, but may be another ref has more. Johnjbarton (talk) 13:33, 18 July 2023 (UTC)

Avoiding discussion of and references to books on QM

I'm reverting an edit that added references to QM books. The books may be fine, but they are not about the article subject, teaching quantum mechanics. Johnjbarton (talk) 14:18, 2 August 2023 (UTC)