Talk:Introduction to quantum mechanics

Uncertainty principle without particles

The current intro says:

• One example of this is the uncertainty principle: if one can predict where a particle will be found, one cannot predict how it will be moving, and vice versa.

I understand that this is the conventional "party line", but it sets the reader into an incorrect mindset for understanding QM. It presumes that QM is a mechanics of "particles" whose properties are difficult to measure. Famously, no evidence supports this point of view. That is why the uncertainty principle is expressed in terms of measurement outcomes, not in terms of hypothetical particle properties.

I will attempt a fix. Johnjbarton (talk) 15:59, 14 November 2023 (UTC)

I changed it to that [1] to avoid exactly that problem; "where a particle will be found" is a statement about a measurement outcome, not a pre-existing property, whereas the old language about "accuracy" implied pre-existing properties. I think precise measurements of position cannot be combined with precise measurements of velocity is on the one hand a bit too vague (what does combined mean here?) while on the other hand it relies on a term that is a bit technical (velocity is fancier than, say, motion or movement). The use of statistically correlated a couple sentences later is likewise perhaps a touch too jargon-y for this place in this article. It's pretty good, but it might need another round of refinement.

Picking superfluidity, of all phenomena, to end the lede with strikes me as rather random. It's less familiar than superconductivity, and the rest of the article barely even mentions it. XOR'easter (talk) 03:16, 15 November 2023 (UTC)

One of the difficulties in a introducing QM is the introductory language needs to be concrete and non-technical but the concepts are technical and not concrete.

Just a suggestion: maybe go with forward reference in the the article without definitions in the intro at all. So when you get to "One example..." change over to "As this article will discuss, concepts like the uncertainty principle and entanglement defy simple explanations in everyday language." This gives space for more words in definition and yet satisfies the idea that the lead is a summary. Johnjbarton (talk) 03:27, 15 November 2023 (UTC)

Including a disclaimer of that sort could be a good idea, maybe right after the "as She is—absurd" bit. We could still say something about the uncertainty principle and/or entanglement after that; I don't think it would be too long. XOR'easter (talk) 04:33, 15 November 2023 (UTC)

Heisenberg

This is a good article but I found it heavily biased toward Schrodinger's 1926 approach. In particular I found no mention of Heisenberg’s work in 1925. As a lay reader it would be interesting if it were possible to write a separate simple high level article explaining how each of the two approaches would have been used to solve an identical problem. Sadly I lack the math’ knowledge to do this myself. RTHill53 (talk) 09:37, 1 March 2024 (UTC)

I agree that a couple of points in the article could mention Heisenberg's work, esp. in the history section. However, this article is not the place to compare or even outline Heisenberg's model. This article reflects the overwhelming consensus that Schrodinger's approach is easier to understand and to leverage for physical insight.

You can read more about Heisenberg's model in Matrix mechanics and Heisenberg's entryway to matrix mechanics. Johnjbarton (talk) 16:08, 1 March 2024 (UTC)

encyclopedic tone

I removed the template:tone after I removed some uses of pronouns. If you have other specific complaints about tone, please add them here. Johnjbarton (talk) 17:29, 16 March 2024 (UTC)

Quantum entanglement

The section on "Quantum entanglement" says

• Nature leaves open the possibility, however, that two electrons can have both states "superimposed" over each of them.

There is no such thing. Quantum states are superimposed. They are not "over" electrons.

• Recall that the wave functions that emerge simultaneously from the double slits arrive at the detection screen in a state of superposition.

Where do I start? "emerge simultaneously" ? "functions...arrive at the screen"? And so on. The section may well be renamed: "Many things to unlearn about quantum mechanics". Johnjbarton (talk) 17:38, 16 March 2024 (UTC)

The fundamental problem with the "Quantum entanglement" section is the doomed attempt to explain these issues using "particle" models. Superposition and entanglement are quantum phenomena, in fact quintessential quantum phenomena.

Unfortunately describing the phenomena correctly with QM with references at an introductory level is not easy. Most introductory texts assume readers want to know about particles and fall in to the trap of giving them what they want. Johnjbarton (talk) 18:19, 16 March 2024 (UTC)