Hacker News Reader

Comment by choeger | Hacker News Reader

Does the article do justice to the hidden variables hypothesis?

In case of the hidden variables, the spin is a (3-dimensional?) value that is identified by the measurement result. In case of quantum theory we have have a probability distribution. How is that probability distribution different from a hidden variables, except that it's not a straight number but a function instead?

Speaking as a programmer, is the difference between hidden variables and quantum mechanics that the former postulate a real-valued property whereas the latter speak of something like a monad?

View on HN

Speaking as a lay person, I think the difference might be that it's specifically about local hidden variables. If two particles are coupled, there's no per-particle hidden variable?

edit-too-late-to-edit: I remembered something that makes me think it's actually more complicated.

If I write 0 and 1 on two different pieces of paper, then flip a coin to decide which paper to give you, we have "entangled" unknowns. When I reveal my paper, we instantly know what's on yours. The joint distribution can't be described per-particle, but we don't consider it spooky. So I think there's something more to it.

Because your example does not contain superpositions. With entanglement the pieces of paper are both 0 and 1 at the same time until they are observed - and only then is it that the superposition of both particles become resolved.

Tomayto - tomahto, right? Physically speaking, what’s the difference between an unresolved superposition and a different kind of unresolved random variable?

Seriously, what's the difference between a non-local variable and a deterministic function that yields a pseudo-random value?

From what I understand, we have some function f that can be evaluated by the measurement and we have another, entangled function g, that can also be evaluated but will yield the opposite of f.

Now instead of assuming that f is truly random and somehow communicates its value instantaneously to g when evaluated, we could also assume that f and g contain a copy of the same pseudo-random number generator and the same seed.

In both cases the interpretation of the model is weird, of course. But I don't see a fundamental difference here that wouldn't allow for hidden variables. It's just that the hidden variables would be have very non-trivial domains.

I think Einstein would've considered nonlocal hidden variables the same as spooky action at a distance.

>How is that probability distribution different from a hidden variables, except that it's not a straight number but a function instead?

Because for entangled particles (separated by a large distance! but also any entangled particle) their PDFs will be correlated in a way that is impossible to define for just a single particle. This makes physicists uncomfortable because of relativity and things happening faster than light.

I believe the QM interpretation is that probability distributions are to be taken literally - a flipped coin under a napkin is both heads and tails with P=.5

Hidden variables on the other hand acknowledges the probability, but contends nevertheless that the coin is actually in a specific but unknown state.

Reply on news.ycombinator.com