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Comment by Xcelerate | Hacker News Reader

At a mathematical level, it's pretty elegant how quantum mechanics works. At the level of the article, not so much.

Once you get the math (and it really kind of clicks all at once), it's not too hard. The problem is that the math has a lot of historical baggage and the ways of translating equations into prose are not the most effective I think.

The whole "uncertainty" thing bothers me. I think there's better ways of expressing this concept to the public.

I am, however, bothered by the fact that QM is not deterministic. Most experiments have ruled out loopholes for a deterministic universe, but it still just weirds me out that randomness is inherent to the measurement of observables.

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There are certainly interpretations of QM that are deterministic. See many worlds, for example.

Personally, I've never found that a comforting alternative.

It just because people tell about it as if all the possible divergent trajectories through phase space happen not just ours. What they actually mean is that the possibilities are vast and we have no idea why reality chose exactly this path because it's not in any way priviledged.

It's like a ball a top of the totally symmetric hill. If you consider phase space it contains ball rolling down in all the possible directions but noone claims that ball rolls in all of them in alternate universes. It rolls down in exactly one way though we might never have any idea why it chose this one.

That sounds exactly like non-determinism, which is what we were trying to avoid.

Do you have any sources for experiments ruling out our universe being deterministic? I'm not questioning you. I honestly have always been intrigued with the idea. Thanks.

The standard answer is the Bell inequalities, but if you only care about deterministic vs. nondeterministic then Conway's "free will theorem" is a bit simpler.

(The result is that either which quantities we choose to measure must be deterministic, or physics must be nonlocal (i.e. what we do in one place can change what we measure in another place even if the two experiments happen simultaneously), or the results of our measurements must be nondeterministic)

Nothing says we live in a local universe.

There's no proof, sure. But nonlocality is very counterintuitive, arguably more so than nondeterminism (and there are no familiar classical/macroscopic phenomena that exhibit nonlocality, whereas many familiar things at least appear nondeterministic in practice).

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