Question

Generate an entangled pair of qubits. Send to Alice and Bob far away from each other. Both measure along basis in one of two possible orientations. The result is sent to Charlie at some later time, who compares the corellations and concludes the Bell inequalities have been violated.

But in Copenhagen, Charlie can say, the pair of results didn't become real until I collected both observations from Alice and Bob. They weren't real when either of them measured them. They only became real once I observed them. Then, both results, when they materialized, materialized at the same place. So, no nonlocality?

Answer 1

Yes, this restores locality, and is sometimes called "Solipsistic Copenhagen". It is described on the first page of Everett's thesis and paper on many worlds. The solipsistic Copenhagen interpretation is the only you can collapse the wavefunction, everyone else is in superposition.

From this interpretation to many worlds is only the step of moving the collapsing entity away from youself, and noting there is no contradiction with experiment, so the whole collapse thing is not really required, and one can logical positivistically remove it from the theory, at the cost of saying that the notion of reality and definite events is not physics, but how the branches get selected by the memories of observers. It moves the question away from physics to philosophy of mind.

While I think this is a neat trick, it might not be nature's trick. One has to be sure quantum mechanics is exact before declaring it so.