Joy Christian wrote:gill1109 wrote:I wonder why there should be any difference. Both versions result in a computer file containing N directions s_k, k=1,...,N. You were worried that with the squishy balls, we might not have a singlet state. And with all that image analysis software, there will be measurement errors as well. But with my computer generated directions, we certainly do have the singlet state: zero total angular momentum; each particle separately has completely random angular momentum.
Again, nice try.
I'm not trying anything. Just wondering how you see that there would be any difference. But it doesn't matter: these are your problems, not mine. I think you should be worried. But you aren't. You think you know something which you think I don't know. I think I know something which I think you don't know.
OK. However you do it, do you agree that the experiment plus computer processing of collected data generates
(A) one computer file containing N directions? [Alice's angular momentum direction; taken to be equal and opposite to Bob's]; or
(B) one computer file containing N pairs of directions? [Alice's and Bob's, not necessarily equal and opposite because of measurement errors and experimental imperfections]; or
(C) two computer files each containing N directions? [One file for Alice, one for Bob; but in one-to-one correspondence. i.e. k'th direction for Alice and k'th direction for Bob both come from the same, k'th run or (synonym) trial.
Next question: how will the directions be represented?
(D) Cartesian coordinates of unit vectors in R^3?
(E) Spherical coordinates of unit vectors in R^3?
(F) Otherwise?
As you well know, when we represent points on a unit sphere in a computer, we have to choose a coordinate frame. In this case, we have to choose two coordinate frames, one for Alice, one for Bob. This is a problem which I think you should be concerned with. I am going to specify measurement directions for Alice and Bob in the same coordinate system as you use, and relative to the same coordinate frames.
(G) Do you have any idea how large N might be?
(H) Will it be known in advance or only after the experiment?
In view of our agreement of how to calculate the correlations, I am not too concerned about non-detections or data-rejections or cleaning or whatever, even if it is of non-local nature (ie based on your experimenters' analysis of the trajectories of both squishy balls).
But I do understand that the experiment is going to generate some number of pairs of directions. So at the end of the day, when I talk about run (or trial) k, k= 1, ..., N, I am referring to the post-selected set of succesful runs which actually generated a pair of directions which you and the experimenter together are happy about.

