- #1
thephystudent
- 123
- 37
According to the EPR-paradox, if we have a pair of two entangled spin-1/2 fermions A and B and measure z-component of A, B collapses immediately as well(i'm using these letters for both particles and their observers). The 'canonical' solution is then to state that it is not possible to transfer information by measuring a particle and hence this does not violate the axioms of special relativity. I have two problems/questions with this.
1)I am not really convinced that measuring A won't transfer any information to B: it transfers the time of measuring. In a (e.g. double-slit-like) interference experiment, it would be possible to test whether B has already been collapsed at time t' or not. And with a sufficient number of entangled pairs, A could then even send any message to B by using a language such as Morse code.
2)Quantum mechanics has been succesfully unified with special relativity by now into relativistic quantum field theories. Now, one of the main aspects of special relativity is the absence of an absolute notion of simultanity. So if A and B collapse together, in which reference frame is that when A and B have a nonzero relative velocity? Maybe the time-coordinate in the FLRW metric of spacetime?
I'm pretty sure I'm not the first one to which these questions occur. I would expect there can be a rigorous argument why my reasoning in 1) is wrong, I don't think 2) is within reach of experiment, but maybe there are theoretical arguments why one of the frames is the important one?
1)I am not really convinced that measuring A won't transfer any information to B: it transfers the time of measuring. In a (e.g. double-slit-like) interference experiment, it would be possible to test whether B has already been collapsed at time t' or not. And with a sufficient number of entangled pairs, A could then even send any message to B by using a language such as Morse code.
2)Quantum mechanics has been succesfully unified with special relativity by now into relativistic quantum field theories. Now, one of the main aspects of special relativity is the absence of an absolute notion of simultanity. So if A and B collapse together, in which reference frame is that when A and B have a nonzero relative velocity? Maybe the time-coordinate in the FLRW metric of spacetime?
I'm pretty sure I'm not the first one to which these questions occur. I would expect there can be a rigorous argument why my reasoning in 1) is wrong, I don't think 2) is within reach of experiment, but maybe there are theoretical arguments why one of the frames is the important one?