Re:How Bell’s Theorem proved ‘spooky action at a distance’ i...
by tylerhou on Tuesday July 20, 2021 @01:02PM
(#27896301)
> it suggest that it’s just a matter of a hidden variable.
I disagree. Suppose that I create a machine that chooses which ball to place in each box. This machine makes the choice based on some measurement of a quantum particle (electron spin). Then the colors of the ball are entangled with the state of the quantum particle, which cannot be described by some local hidden variable.
Re:How Bell’s Theorem proved ‘spooky action at a distance’ i...
by lisper on Tuesday July 20, 2021 @01:06PM
(#27896353)
Only if you can completely isolate the balls so their states don't decohere. That is not practically possible to achieve, particularly since in your scenario you reach into the bag and touch the balls. As soon as you interact with the balls in any way, you become entangled with them and the behavior of the system becomes classical.
Re:How Bell’s Theorem proved ‘spooky action at a distance’ i...
by serverholic on Tuesday July 20, 2021 @05:20PM
(#27899516)
You didn't add anything to his example. This is just purely to be pedantic.
Re:How Bell’s Theorem proved ‘spooky action at a distance’ i...
by lisper on Tuesday July 20, 2021 @05:26PM
(#27899595)
No. The only way you can actually observe entanglement is in an isolated entangled system (this is the reason quantum computers are hard to build). It is true that at a philosophical level there is no difference, but from the point of view of physics, which is to say, what is observable, isolation is crucial. Non-isolated systems behave classically, notwithstanding that they are actually quantum systems.
Re:How Bell’s Theorem proved ‘spooky action at a distance’ i...
by tylerhou on Tuesday July 20, 2021 @06:09PM
(#27899991)
Would you claim that when Einstein developed his theories of relativity, they were invalid (from the point of view of physics) because their consequences were not yet observable? For example, Einstein used thought experiments to develop special relativity in 1905, but since kinematic time dilation was only experimentally confirmed in 1971, his work was not a contribution to physics until then?
Re:How Bell’s Theorem proved ‘spooky action at a distance’ i...
by lisper on Tuesday July 20, 2021 @07:02PM
(#27900382)
The difference is that the limits on observing relativistic effects in 1905 were technological, whereas in QM you cannot observe the effects of entanglement in a non-isolated system even in principle. This is a fundamental constraint imposed by the theory itself. You can't get around it even with arbitrarily advanced technology.
Re:How Bell’s Theorem proved ‘spooky action at a distance’ i...
by naasking on Tuesday July 20, 2021 @04:44PM
(#27899057)
> The analogy you mentioned is exactly the wrong one - it suggest that it’s just a matter of a hidden variable.
It is equivalent to a hidden variable, just a non-local one.
Re:How Bell’s Theorem proved ‘spooky action at a distance’ i...
by kolinko on Wednesday July 21, 2021 @06:08AM
(#27904312)
his analogy suggests there is a local hidden variable.
A proper (but less elegant) would be: you have two balls with the same color or a pattern.
You take one out. If you check the color first, you will find the other’s color the same, but the pattern sometimes different. If you check the pattern first, you will find the pattern the same, but the color sometimes different.