Really? "Correlations have physical reality; that which they correlate does not." does not mean correlations fall from the sky but quite the opposite?He does quite the opposite.
You claim the very thing in the same post. You say non-realism/contextuality allows violation of Bell inequality without non-locality. Unless you attribute non-realism/contextuality to detections themselves you are proved wrong by Eberhard.So? Who claimed that it does?
If I had to bet money, I would always go for non-realism/contextuality or whatever you would like to call it.
Yes, experiments support it, but I disagree that relativity is not being questioned, at least unconsciously.No one is questioning relativity per se. Experiments support it.
But qft is a strictly local theory. I have an entire textbook devoted to that very thing, "Local Quantum Physics: Fields, particles, Algebras," Rudoplf Haag.(And as a point worth mentioning, the equations of relativity are time symmetric anyway. So that could potentially explain the appearance of quantum nonlocality, although that is speculation at this time.)
And in the typical Bell type experiment, the detectors are separated from the source by null intervals, since obviously, photons live on the light cone. So between the source and each detector, the distance is zero, regardless of the spatial seperation between the detectors. That seems to be a missed point.But there seems to be a gray area when it comes to entangled systems: they have spatial extent but act as if that extent doesn't constrain the system as might be otherwise expected.
I really have no idea what you are trying to say here.And on the quantum side: ordering of the following makes no discernible difference to the outcome in any reference frame:
a. Pair A and B entangled.
b. A measured.
c. B measured.
Define a "preferred frame" that is consistent with relativity. The only definition of "preferred" that makes sense is one in which the measured values are some "true values" to which other frames can be referenced and not lead to contradictions.I'm not sure I understand. You are a bit too short for me to get what you mean.
I gave definition of "sample space": In probability theory, the sample space of an experiment or random trial is the set of all possible outcomes or results of that experiment.I'm using it in the same sense as in probability theory. See Chapter 6 of Streater's "Lost Causes in Theoretical Physics". He has a good explanation of it.
You can take any inertial reference frame in SR and label it as preferred. Then label any measured values in that reference frame as "true values" and measured values in other inertial reference frames as "apparent values". No inconsistency with SR arises because nothing in the math of SR was changed by that labeling.Define a "preferred frame" that is consistent with relativity. The only definition of "preferred" that makes sense is one in which the measured values are some "true values" to which other frames can be referenced and not lead to contradictions.
Sorry, this thread is predicated on a falsehood. Entanglement is a known and understood consequence of many particle quantum mechanics. And it does not enable communication of any kind, faster or slower than the speed of light.As far as I can tell nobody actually knows how quantum entanglement really works,[...]
You would have to reject fundamental relativity, but you would not have to reject effective relativity valid only under restricted set of circumstance. This restricted set of circumstances must involve all experiments performed so far, but one cannot exclude the possibility that some future experiments, perhaps experiments with the next generation of particle colliders, will show violations of relativity.But that cannot be correct. The measurements are spacelike separated, so they are made simultaneously. Neither measurement can occur "before" the other and create a cause and effect relationship because they cannot be time ordered. You would have to reject relativity. Apparently, what people must be arguing about is whether relativity is correct.
I am really and honestly puzzled as I really think this is trivial. If you have two quantities that are connected via some kind of uncertainty relation, you can prepare states, in which one of these properties is well defined, while the other is not (or both are defined to some extent). If I prepare a state of known position, momentum is ill-defined and vice versa. For entangled states, entanglement and coherence in the entangled property are another pair of properties connected via an uncertainty relation. Entanglement boils down to the presence of non-classical correlations of some chosen property. Coherence boils down to sharply defined values of this property. So if I prepare a state such, that the individual properties (e.g. the spin of two photons) are well defined, well-defined non-classical correlations cannot exist. If I prepare a state with well-defined non-classical correlations, well-defined values of the individual properties cannot exist. Correlations are an element of reality in the latter case, while the correlated quantities are not. In order to achieve this, you simply have to prepare an entangled state (or equivalently prepare well-defined non-classical correlations - and to emphasize it again: ONLY the correlations, not the individual spin/energy/OAM/polarization/whatever values). You need to explicitly prepare the state as such. I do not see why explicit preparation of such a state would correspond to falling from the sky.Really? "Correlations have physical reality; that which they correlate does not." does not mean correlations fall from the sky but quite the opposite?
We have communication problem.
I disagree. Eberhard explicitly develops several concepts of locality in his paper(s) (Bell's Theorem and the Different Concepts of Locality, Il Nuovo Cimento 46, 392 (1978)). Concepts 1-3 more or less lead to deterministic or probabilistic LHV theories and are at odds with quantum theory. Notion 4 is the simple relativistic notion of locality, which means no FTL-signaling and is not at odds with quantum theory as explicitly pointed out by Eberhard. This is the relevant notion of locality in this case.You claim the very thing in the same post. You say non-realism/contextuality allows violation of Bell inequality without non-locality. Unless you attribute non-realism/contextuality to detections themselves you are proved wrong by Eberhard.
I'm not using Streater to give a definition of sample spaces, as I said I am using the normal definition in Probability theory as Wikipedia gives. He just gives a good example of how QM uses multiple sample spaces.I gave definition of "sample space": In probability theory, the sample space of an experiment or random trial is the set of all possible outcomes or results of that experiment.
Is that the definition you are using?
It seems that the book you gave was freely available online some time ago but it is no more. But "sample space" is such a basic concept in probability theory that it should not require specific book to give it's definition. Googling gave plenty explanations of this concept and they were all consistent with definition I gave.
Just to make it very clear: I do not state that QFT is classically local. That contradicts the plethora of Bell tests that prove QFT to be not compatible with local deterministic HV models. Mermin's article, of course, is a gem!
Also just to make it clear: I intended to say that it is not warranted to assume that you think that QFT is classically local. I did not intend to say that your position is unwarranted because you think that QFT is classically local. My post might have been easy to misinterpret. ;)Just to make it very clear: I do not state that QFT is classically local.
It's not quite true its ruled out - things just come out more rationally and elegantly if you rule it out. It like the aether in LET. I can't rule LET out - all I can do is give a very elegant explanation of SR based on symmetry rather than an inherently undetectable aether. Things get more and more difficult the deeper you go into areas like GR and QFT. Its scientific tact really that's actually at the base of what's in many of our theories. I know its not entirely satisfactory things in science are like that. I believe the cluster decomposition property as explained by Weinberg makes things harder if you allow the concept of locality to apply to correlations. Of course you can do it - but one must ask why?To the contrary it's ruled out by the very construction of this QFT as made explicit in Weinberg's books much more explicitly than in most other QFT textbooks.