DrChinese said:
We all know we are never going to change Bill's* mind. Every experimental form of entanglement is essentially a refutation of every local realistic viewpoint. If you simply deny this, as Bill does, well... here we are.
*As he is not likely to change mine.
I like the attempt to get past disagreements about the meaningfulness or validity of abstract arguments by making it into an Amazing-Randy style wager:
The Bell side makes a bet, that there is no way to simulate EPR-style correlations without nonlocal communication, using a combination of deterministic devices plus random number generators.
The challenge is to design a "pair generator" that will produce a sequence of pairs of "secret messages", together with a box, "Alice's detector" and "Bob's detector" that will receive a secret message, together with a real-number input from Alice or Bob, and will output either +1 or -1.
The challenge proceeds as follows: We pick a number of rounds, say 100. Each round proceeds as follows: On round number n,
- The pair generator creates a pair of secret messages m_{A,n} and m_{B,n}, and sends m_{A,n} to Alice's detector, and m_{B,n}to Bob's detector.
- Alice rolls a 6-sided die. If the result is 1 or 2, she picks \alpha_n = 0°. If the result is 3 or 4, she picks \alpha_n = 120°. If the result is 5 or 6, she picks \alpha_n = 240°. She inputs the value into her detector.
- The detector produces an output, either A_n =+1 or -1, which is only seen by Alice. She records her choice of \alpha_n and the output A_n from the detector.
- Bob similarly chooses \beta_n from the set { 0°, 120°, 240° }.
- Bob's detector produces an output, either +1 or -1, which is only seen by Bob. He records his choice of \beta_n and the output, B_n from his detector.
After many rounds, Alice and Bob each have a list of pairs. They put their lists together to compute joint probabilities as follows:
P(\alpha, \beta, A, B) = \dfrac{N_{\alpha, \beta, A, B}}{N_{\alpha,\beta}}
where N_{\alpha, \beta, A, B} is the number of rounds in which Alice chose \alpha_n = \alpha, and Bob chose \beta_n = \beta, and A_n = A and B_n = B, and where N_{\alpha, \beta} is the number of rounds in which Alice chose \alpha_n = \alpha and Bob chose \beta_n = \beta.
The bet is that there is no way to design the "pair generator" and the "detectors" so that the simulated joint probability distribution P(\alpha, \beta, A, B) agrees with the quantum spin-1/2 EPR predictions:
P(\alpha, \beta, +1, +1) = P(\alpha, \beta, -1, -1) =\frac{1}{2} sin^2(\frac{1}{2} (\beta - \alpha))
P(\alpha, \beta, +1, -1) = P(\alpha, \beta, -1, +1) =\frac{1}{2} cos^2(\frac{1}{2} (\beta - \alpha))
Where the "local" comes in is the assumption that Bob's detector is not allowed to use Alice's input, and vice-versa, and that the pair generator is not allowed to use either input. If you violate these locality restrictions, it's easy to get the QM results.