Was John Bell right when he said Einsteines EPR paradox led to testable differences between:?

Question

Quantum mechanics and local hidden variable theories?

Answer 1

Absolutely. The EPR (Einstein, Podolsky, Rosen) paradox is a thought experiment that has to do with what is known as 'quantum entanglement' and the (apparent) ability of quantum states to affect each other instantaneously over long distances. And there have been many experiments done that verify the observation. 'Quantum Weirdness' is a fairly deep subject and one with which even Einstein was never totally comfortable. But it does appear that things such as 'hidden variable' and 'non-linear guage' type theories have just about been ruled out as being able (within the framework of SR and GR) to explain quantum reality results.


Doug

Answer 2

If I remember correctly Bell came up with a simple "disequation" (an equation involving inequality and not equality) which was able to exclude that Quantum Mechanics was an incomplete theory but was in fact very complete and so cannot tell us more about the "real" world. Some people used to think (even nowadays I guess) that Quantum Mechanics was an incomplete theory because there are certain hidden variables the physicist has no access to and therefore their knowledge would complete all the information on the system. Bell devised an experiment, later improved by Alan Aspect, etc, to prove this: we have complete knowlegde of variables involved in quantum phenomena and quantum mechanic predictions are probabilistic in their "intimate" nature. It's not like studying the roll of dice. We give this macroscopic experiment a probability just because it is practically impossible to take into account all of the system's variables to predict the final outcome. The important point is that it is theoretically possible to do so. Newton's laws tell us that, it's just tremendously difficult and time consuming. Instead quantum mechanics is intrinsically probabilistic in its "weird" nature and much more like "things are not real before you measure them".

Answer 3

maybe

Answer 4

Dunno!