Talk:Quantum mechanics

Ape Brains
"Interpretations usually try to translate quantum physics into classical physics terms so our piddly ape brains can grasp it all". The problem as I understand it is that QM is inherently formulated in terms of our ape brains and explicitly invokes them when it talks about the subjective idea of "measurement". The point of the various realist interpretations is to try to bring QM back in line with the other branches of science, which try to provide an objective picture of the world.
 * Could you rephrase this point into coherent sentences please? CorruptUser (talk) 18:58, 6 September 2015 (UTC)

The point is that QM just straight up says "measurement causes collapse" without explaining what measurement is. The collapse postulate contradicts all the other laws of QM, which means that there is no quantum mechanical account of how measurement works as a physical process. The standard, Copenhagen way of dealing with this is to say that the wavefunction, and wavefunction collapse, is just a subjective thing invented by our ape brains, instead of something real.
 * I object to the idea that I have a brain. Scherben (talk) 15:13, 8 August 2017 (UTC)

Atomsol?
WTF is that word doing in the top line? An error?? Ithaca8 (talk) 18:00, 4 April 2017 (UTC)
 * Thanks for pointing that out, I corrected it. (In future you could just edit it yourself you know, if you turn out to be wrong it can always be put back). Christopher (talk) 18:07, 4 April 2017 (UTC)

Many Worlds
The article currently reads: "Religious people are likely to be uncomfortable with many worlds."

Skeptical people might also be uncomfortable with ideas that lack anything resembling evidence. &mdash; Unsigned, by: 173.48.126.79 / talk 03:01

Actually Bryce DeWitt, who coined the term "many worlds", was religious. The simple truth is that most people are uncomfortable with many worlds, for reasons that have nothing to do with religion.
 * I'm not seeing the phrase in the article. It was probably removed for unfairly singling out religious people. 08:20, 21 November 2021 (UTC)
 * Would 'Many worlds (ie states of existence, not exoplanets)' be an appropriate clarification?

Would 'this might explain why witnesses to an event have very different interpretations of what happened' be a creative misunderstanding of what is meant by QM in this context (ie each person is in a different 'state' at that particular point in time)? Anna Livia (talk) 13:14, 21 November 2021 (UTC)

Simplistic error
"First the quantum state can be mathematically proven to be a type of probability distribution and also obeys several inferential and decision theoretic theorems. >>>This means its mathematical properties are in line with viewing it as a summary of knowledge.<<<"

This is completely false. If the wavefunction was just a summary of knowledge we would have classical physics. The statement is a complete misunderstanding of quantum mechanics, and entirely misrepresents or glosses over the measurement problem in quantum theory. The entire paragraph should be deleted.


 * I'm not wishing the defend this specific sentence, but I think it is important to keep in the article the notion that quantum physics is consistent mathematically, allows falsifiable predictions, and follows and is limited by rules. RW is mainly about reacting to pseudo-science and such, and a lot of pseudo-science involving quantum physics are missing this point and keep thinking that quantum physics is magical. In fact, quantum physics is as "classical" as any domain where particular states cannot be determined and that we end up with statistic on population, this goes from climatology to assurance risk assessment. Sure, they are due to the fact that we can't measure with precision an enormous amount of initial conditions while quantum physics is inherently probabilistic, but in practice, a lot of pseudo-science treats quantum physics in a way they could not treat those other domains. In summary: I think it's worth noticing that the measurement problem is way less important in practice than a lot of people think, and that in practice, quantum mechanics is just a math problem. 84.69.29.79 (talk) 12:51, 21 November 2021 (UTC)

In practice there is no problem at all. As you say, quantum theory gives precise, albeit probabilistic, answers. But there is a measurement problem, although it is a "only" a philosophical problem. Perhaps the article should say just that. But the resolution is not to imply that there is no problem in the CI because we can "just" treat the wavefunction as a receptacle of our knowledge. If it was that simple there would be no controversy over the interpretations of QM.

Updates
I have made a few technical updates, where the physics was incorrect or outdated (e.g scepticism over the Higgs discovery).

Proposed restructure

 * Overview
 * Old QM (popular examples, high school and early undergraduate stuff)
 * QFT and The standard model (note it exists and that's where the research is)
 * Quantum and biology (of special interest to woo and pop science)
 * Philosophy
 * Woo

That is, almost the current structure. Just re-sort a few errant sections and add overview paragraphs. Looi (talk) 09:17, 6 April 2022 (UTC)