Hacker News Reader

Comment by kavalec | Hacker News Reader

"Interestingly, both alternative classical mechanics and quantum theories can be supplemented by additional variables in such a way that the supplemented theory is deterministic."

This sounds like "hidden variable" and is not true for quantum physics.

View on HN

It is, but you need to give up more and allow information to travel faster than light speed.

It's local hidden variables that are a problem.

Non-locality != faster-than-light communication

As I understand it 'Spooky action at a distance' does not allow communication, but in for hidden variable theory to work a particle needs access to another particles hidden variables. Unless you want to suggest another model?

Why is non-locality a problem for hidden variables theories and not for the "standard" interpretation of quantum mechanics?

Quantom mechanics is based on non-locality, that's one of the things people have problems with.

Quantum key distribution for example is seems to be based on this https://en.wikipedia.org/wiki/Quantum_key_distribution.

As to the truth well ¯\_(ツ)_/¯

I thought you said that the hidden-variables extension of quantum mechanics is "bad" (compared to the "vanilla" QM) because you need to allow information to travel faster than light speed.

But I agree if you meant that QM (both non-local hidden-variables and standard interpretation) requires non-locality, unlike local hidden-variables theories which are ruled out by the violation of Bell inequalities which has been established experimentally.

Hidden variables where specificly proposed as a solution to non-locality. So, I just mean bad in that they did not solve that problem.

True. However, unlike the "standard" QM interpretation, the non-local hidden-variables theories are deterministic (which is the reason why they were mentioned in this thread a few messages back).

Local hidden variables are not true. Nothing is said about global hidden variables.

Where could I find out more about these particular kinds of models for QM?

Yes, the very next sentence of the abstract says:

> Most physicists straightforwardly supplement classical theory with real numbers to which they attribute physical existence, while most physicists reject Bohmian mechanics as supplemented quantum theory, arguing that Bohmian positions have no physical reality.

Bohmian mechanics is a hidden variable theory.

Reply on news.ycombinator.com