I think I still don't understand the difference between superdeterminism and strict determinism. Can you explain the GENERAL difference between these two concepts, without referring to QM and nonlocality?In superdeterminism, the choice of an experimenter's measurement setting is controlled by initial conditions in just such a way as to allow Bell's Inequality to be violated. In strict determinism, the experimenter's choice of measurement setting is not "free", but Bell's Inequality is not violated as a postulate of the theory. Instead, there is some other mechanism (in your case non-locality) which is responsible.
In ordinary determinism: [initial conditions] + [physical laws] -> [observed results]. However, there is no reason that this would ever lead to violation of a Bell Inequality. Why would it? There would be no reason that a measurement setting at Alice would be somehow correlated with a result at Bob - at least certainly no more likely than a result involving unentangled particles elsewhere (let's say Chris).I think I still don't understand the difference between superdeterminism and strict determinism. Can you explain the GENERAL difference between these two concepts, without referring to QM and nonlocality?
Anyway, in Bohmian mechanics both the initial conditions and nonlocal forces are responsible for the violation of Bell inequalities as predicted by standard QM. The initial conditions are important because the initial particle positions in the statistical ensemble must be distributed according to |psi|^2, which corresponds to the so-called quantum equilibrium hypothesis. If this initial condition has not been satisfied, then the violation of Bell inequalities could be even stronger than predicted by standard QM (see the papers of Valentini).
It is irrelevant for dBB. They postulate some maximal speed of information transfer, which is violated on the hidden variable level in dBB.That seems a weird reference for you to agree with... they claim it rules out all deterministic theories (including Bohmian/dBB type) other than superdeterministic ones. Nice paper, by the way, covers a lot of interesting ground.
I think that this "free-will theorem" is a good example of how untenable the position against the existence of hidden variable theories has become.
I don't know. I just tried to imagine some attempt. Below is a naïve idea.And how does this transmit information FTL?
I definitely believe an experimenter has free will to choose a measurement setting, for all intents and purposes. I realize that at some level, there could be complete determinism but that doesn't change my view as a good and useful hypothesis.Thank you for the clarifications, Dr. Chinese.
Anyway, I still claim that the free-will theorem, which in its refined version essentially says:
"If experimenters have free will than observed particles also have free will"
does not rule out BM, simply because in BM experimenters do not have free will.
Do you still disagree?
I think this is an exaggerated statement. The no-go work on hidden variables is quite extensive, although it is not yet what I would call persuasive. On the other hand, no amount of experimental effort has been able to uncover even a hint of a hidden variable anywhere (of course to a Bohmian, the hidden variables are literally everywhere). That is strongly suggestive, but still not conclusive. So I think it would be manifestly unfair to characterize a single approach (such as Conway & Kochen) as representative of the entire interpretation.I think that this "free-will theorem" is a good example of how untenable the position against the existence of hidden variable theories has become.
A lovely attempt, but not likely to get anywhere... on the positive side, if it did, you'd probably get a Nobel prize.alxm,
I don't know. I just tried to imagine some attempt. Below is a naïve idea.
There is in fact an interesting nuance on this particular item. No actual test - that I am aware of, at least - has been done to confirm what we assume the result will be (which is continued correlation). Now why would this matter?I don't see why the age difference in the particles should prevent them being correlated. why should there be any change in entanglement?
Its up to you to say why entangled particles of different ages (brought about by a high speed relativity trip) remain in the exactly the same correlation even though one is two days older than the other.I don't see why the age difference in the particles should prevent them being correlated. why should there be any change in entanglement?
I almost agree:The "theorem" is nothing but a tautology (if the particles in the experimenter's brain are not described by a deterministic theory it follows that all other particles share this property). Given that there is no evidence that a brain consists of a different type of particles than the rest of the world there is nothing more to prove, no reason to appeal to EPR or even to QM. The "proof" follows from logic alone.
Well, the obvious point is: if Alice is observed after .001 second, and Bob is observed at any time thereafter (so that Bob is older), the correlation remains (as predicted by QM). So the only issue relates to the effect, if any, of having Bob interact with a gravitional field. Does that cause decoherence and therefore end entanglement? As of today, this is entirely an open question and there is no evidence either way. Feel free to speculate...Its up to you to say why entangled particles of different ages (brought about by a high speed relativity trip) remain in the exactly the same correlation even though one is two days older than the other.
What is it about entanglement that did not change?
First, that is not a question about asserting - or there is equivalence, or there is not. Once there is a theorem about equivalence in quantum equilibrium, there is no possibility, if we are trapped in equilibrium. Very sorry, but there is no choice.I do believe that the BM/dBB school needs to quit asserting that there is *no* possibility of a testible difference between QM and BM. If there isn't, what is the value of BM as a theory? It simply becomes an ad hoc explanation for existing facts. The sQM school is taking the possibility of verifying or rejecting BM seriously; and I would like to see more of that attitude.
I cannot agree more.There are important metaphysical differences, in particular there is no measurement problem, no nonunitary evolution of the wave function, and, very important, the whole measurement theory postulated in QM can be derived from something much more simple. Given the simplicity of this derivation, BM should be preferred by the usual standards of preference for the simpler theory.
My personal interest is to understand how the universe works. It is not to find some theory which differs in some prediction from the standard one - if it happens that such a modification allows for a much simpler understanding of our universe - fine, I will embrace it.
That's fair. However, I think that the question "Does entanglement violate special relativity?" cannot be answered irrespective of the interpretation one works with. Thus, it is interesting to see how different interpretation answer this question. One of the interpretations is the Bohmian one, and that's how we arrived at it.I cannot agree less! We are discussing "Does entanglement violate special relativity" not pushing Bohm - you don't seem interested.
The questions are closely related. First, it seems unjustified to take some part (entanglement) out of quantum theory and to ask separately if it "violates relativity". It is quantum theory as a whole which violates (or not) relativity.I cannot agree less! We are discussing "Does entanglement violate special relativity" not pushing Bohm - you don't seem interested.
Sorry, in the quantum context there is no violation of causality. Again, pilot wave interpretation is the explicit counterexample. One with formulas and theorems.It is not SR but CAUSALITY which is violated
But causality is somehow volated in the closed timelike loops, so GR also violates causality.