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 [itex]n[/itex],
- The pair generator creates a pair of secret messages [itex]m_{A,n}[/itex] and [itex]m_{B,n}[/itex], and sends [itex]m_{A,n}[/itex] to Alice's detector, and [itex]m_{B,n}[/itex]to Bob's detector.
- Alice rolls a 6-sided die. If the result is 1 or 2, she picks [itex]\alpha_n =[/itex] 0°. If the result is 3 or 4, she picks [itex]\alpha_n =[/itex] 120°. If the result is 5 or 6, she picks [itex]\alpha_n =[/itex] 240°. She inputs the value into her detector.
- The detector produces an output, either [itex]A_n =[/itex]+1 or -1, which is only seen by Alice. She records her choice of [itex]\alpha_n[/itex] and the output [itex]A_n[/itex] from the detector.
- Bob similarly chooses [itex]\beta_n[/itex] 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 [itex]\beta_n[/itex] and the output, [itex]B_n[/itex] 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:
[itex]P(\alpha, \beta, A, B) = \dfrac{N_{\alpha, \beta, A, B}}{N_{\alpha,\beta}}[/itex]
where [itex]N_{\alpha, \beta, A, B}[/itex] is the number of rounds in which Alice chose [itex]\alpha_n = \alpha[/itex], and Bob chose [itex]\beta_n = \beta[/itex], and [itex]A_n = A[/itex] and [itex]B_n = B[/itex], and where [itex]N_{\alpha, \beta}[/itex] is the number of rounds in which Alice chose [itex]\alpha_n = \alpha[/itex] and Bob chose [itex]\beta_n = \beta[/itex].
The bet is that there is no way to design the "pair generator" and the "detectors" so that the simulated joint probability distribution [itex]P(\alpha, \beta, A, B)[/itex] agrees with the quantum spin-1/2 EPR predictions:
[itex]P(\alpha, \beta, +1, +1) = P(\alpha, \beta, -1, -1) =\frac{1}{2} sin^2(\frac{1}{2} (\beta - \alpha))[/itex]
[itex]P(\alpha, \beta, +1, -1) = P(\alpha, \beta, -1, +1) =\frac{1}{2} cos^2(\frac{1}{2} (\beta - \alpha))[/itex]
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.