The general way I have thought about causality for a while is that the fact that nature violates Bell's inequality means we have to throw out one of two things (1) reality, or (2) causality/locality. Since GPS proves relativity is correct so we know it is the first assumption must be thrown out.
[That is we know there is space-time, but things have no space-time coordinate until observed.]
There would be no reason to mention this except that I noticed the locality (causality) also comes up in QM in terms of showing that Dirac particles (of 1/2 spin) must be fermions (obey the Pauli exclusion principle) and can not be bosons.
You need the commutator [ψ (x, 0), ψ*(y,0)] must be zero because the separation between x and y is space-like. So it seems to me that an important result in QM depends on the fact that there can be no effects that are not local. (The star * I mean as the complex conjugate transposed).
The fact of locality is denied so often that I feel it is important to mention this more than once.
The nicest explanation of this subject I saw in a free book of lectures on QM by Dr. Doren Cohen in Beer Sheva. He explained the subject of Bell's inequality very nicely. Later on on I noticed in the lectures of Allan Guth at MIT how the fact that things with integer spin can not obey the Pauli exclusion principle depends on relativity [no action at a distance].
[That is we know there is space-time, but things have no space-time coordinate until observed.]
There would be no reason to mention this except that I noticed the locality (causality) also comes up in QM in terms of showing that Dirac particles (of 1/2 spin) must be fermions (obey the Pauli exclusion principle) and can not be bosons.
You need the commutator [ψ (x, 0), ψ*(y,0)] must be zero because the separation between x and y is space-like. So it seems to me that an important result in QM depends on the fact that there can be no effects that are not local. (The star * I mean as the complex conjugate transposed).
The fact of locality is denied so often that I feel it is important to mention this more than once.
The nicest explanation of this subject I saw in a free book of lectures on QM by Dr. Doren Cohen in Beer Sheva. He explained the subject of Bell's inequality very nicely. Later on on I noticed in the lectures of Allan Guth at MIT how the fact that things with integer spin can not obey the Pauli exclusion principle depends on relativity [no action at a distance].
