minkwe wrote:Clearly, Richard is saying here that there are outcomes of measurements not actually performed which are assumed to exist alongside outcomes of measurements actually performed. In response to earlier questioning, he clarified that by "exist", he wasn't talking about the real-world, just "exist" in a mathematical sense. So my question to Richard remains. He needs to point out which terms represent outcomes from performed measurements and which represent outcomes from non-performed measurements in Bell's 14a.
I think I already answered this. I wrote: The derivation of that inequality is done under some assumptions: of existence of a variable called lambda, and of functions called A and B, and it involves the expressions A(a, lambda) = - B(a, lambda), A(b, lambda) = -B(b, lambda), A(c, lambda) = -B(c, lambda). These represent the outcomes which would have been observed, had Alice used settings a, b or c; and the negatives of the outcomes Bob would have observed, had Bob used settings a, b, or c. The derivation of the inequality you mention does not assume that Alice or Bob actually do anything at all. It does assume determinism, and locality. It assumes that some deterministic evolution of the entire physical system under study takes place, such that a measurement outcome is a deterministic function of the state of the entire system being studied, together with the locally introduced setting. Part of the description of the state is the list of positions and momenta of all the particles involved at some initial time point prior to the choice of settings by Alice and Bob. Then they each press a button selecting a setting. Then a short time later pieces of paper are printed with “+1” or “-1” written on them.
Transitioning and generalising to the CHSH situation, according to the model, if Alice actually does choose to use setting “a”, she’ll get to see the outcome A(a, lambda), whereas if she had used a’, she would have seen A(a’, lambda). Similarly for Bob. If he tosses a coin to use setting b or b’, he’ll get to see B(b, lambda) or B(b’, lambda). (We no longer assume perfect anticorrelation at equal settings, so no relationship between the functions A and B is assumed). But anyway, alongside of the actually observed outcomes belonging to the actually chosen settings, there are also defined the counterfactual outcomes which would have been observed, had the other setting been chosen.
You are free to find these assumptions stupid. Anyway, it turns out that they conflict with quantum mechanics, so if you believe quantum mechanics, and the experiments which confirm it, you had better abandon them.
I don’t see what the problem is. Bell makes some assumptions which you don’t like, and under those assumptions, derives consequences which are contradicted by experiment. Niels Bohr would have been bored. David Bohm was delighted. But Einstein would have been deeply disturbed.
Regarding the paper by Karl Hess, Hans de Raedt and Kristen Michielsen
https://arxiv.org/abs/1605.04889Counterfactual Definiteness and Bell's Inequality;
Abstract: Counterfactual definiteness must be used as at least one of the postulates or axioms that are necessary to derive Bell-type inequalities. It is considered by many to be a postulate that is not only commensurate with classical physics (as for example Einstein's special relativity), but also separates and distinguishes classical physics from quantum mechanics. It is the purpose of this paper to show that Bell's choice of mathematical functions and independent variables implicitly includes counterfactual definiteness and reduces the generality of the physics of Bell-type theories so significantly that no meaningful comparison of these theories with actual Einstein-Podolsky-Rosen experiments can be made.
Unfortunately these folk don’t understand much. They think that there are big problems concerning time in Bell experiments. However they are wrong. We could start a new topic and I would be happy to point out the misunderstandings and self-contradictions in this paper which I see rather easily. It seems that they want to assume dependence between the experimenters’ setting choices and the microvariables describing the physical system of source and detectors. Indeed, Bell’s theorem assumes that settings can be chosen freely. These folk apparently believe in superdeterminism. Bell’s theorem is correct, as a mathematical theorem; they avoid its consequences by violating “no-conspiracy”. They *do* believe in local realism, in determinism.
The paper was originally submitted by Karl Hess to the journal PNAS. He’s a member of the US Academy of Sciences, and hence has the prerogative of getting things published there, despite negative referee reports. But the paper finally appeared elsewhere. It has by now been cited 11 times, mainly by the authors themselves. It seems that not many people understand (or agree with) what the authors are saying. Perhaps Michel would like to expound their point of view in a new thread.