Einstein and entanglement

When I was preparing a lecture, I again wondered what would Albert Einstein think today about the interpretation of quantum mechanics if he knew all the experiments that show that his ideas were patently false and that quantum mechanics is absolutely right. Especially the cute experiment described by Mermin - and also by Brian Greene in Chapter 4 of his "The Fabric of the Cosmos".

The world cannot be described by local hidden variables that would act as a "completion" of quantum mechanics, in the sense that Einstein envisioned. Einstein would have a hard time to decide what to think. Either he would abandon his deterministic preconceptions and accept the probabilistic nature of quantum mechanics just like all other serious physicists; or he would continue to think that the world is described by nonlocal hidden variables.

Einstein disliked quantum mechanics but he also disliked nonlocality. I feel that he would finally reject to sacrifice locality - and he would reject to introduce material signals that propagate faster than light. They would be in such a clear contradiction with everything that Einstein believed about locality in space and time and about the local character of the physical law that he could even decide to sacrifice the "objective existence" of some degrees of freedom that describe reality prior to the measurement.

More realistically, I think that Einstein would be saying similar things about the interpretation of quantum mechanics as Prof. Roger Penrose does, and they would also fail to make sense to anyone else. ;-)




More generally, it is an interesting exercise to try to imagine how would Isaac Newton react if someone visited him in the past - or revived him in the present - and showed him the current picture of the world based on quantum mechanics, relativity, and maybe even string theory. I feel that Newton would master all these things very quickly and he would be immensely pleased. And maybe he would not. At any rate, this is an interesting thought experiment that gives us a clue how would the future developments of theoretical physics affect our feelings.