Questioning assumptions behind Bell's and related theorems

[Nugatory]

This is a red herring.

Not for MorroBay's argument, where he suggests that there is a causal relationship between the observation at one station and the result at the other station.

 

[Nugatory]

I would disagree that "relativity of simultaneity" has anything to do with the perplexing ftl effects. You can see that quantum ordering is irrelevant in many cases in which ordering is absolute. An example is entanglement swapping such as this:

Ah, you're right, there's a bottomless supply of perplexity here

MorroBay was proposing a causal relationship between the observation at one station and the result at the other, and RoS is (for me, at least, and I expect some company here) a problem for that line of thinking.

 

[billschnieder]

In the reasoning that leads up to Bell's inequality, it is assumed that the choice of the hidden variable is independent of the choice of settings of distant measurement devices. That might not be the case. If the world is deterministic, then the settings of detectors is determined long in the past, and so it is possible to choose the hidden variable in a way that takes into account the future settings. (Actually, there's an interesting--to me--question about whether superdeterminism requires that twin-pair sources and detectors have an overlap in their backward lightcones.

As Accardi proves in the paper cited at the beginning of this thread, the assumption that "the choice of the hidden variable is independent of the choice of settings of distant measurement devices" is the same as the assumption "that the random variables are defined on the same probability space" and that is the only other assumption assumption required to obtain the inequalities together with the assumption of outcomes (+1, -1).
Note that what most people call the "realism assumption", or the "counterfactual definiteness" assumption, are simply variants of this assumption, albeit while using non-standard definitions of "realism" or "CFD". Accardi has distilled it down to the essential mathematical assumption and clearly reveals that you do not need any physical assumption to obtain the inequalities.

Superdeterminism is not the only way to violate the requirement of "the same probability space". QM violates this requirement because non-commuting measurements by definition do not have the same probability space. The authors discuss other mechanisms way more reasonable than superdetermism. See for example the discussion on page 16.

If I may summarize:
* Some λs may not be measurable at certain detector angles, which means non-detection of particles may not be a problem of "detection efficiency" but rather due to the mechanics of the particle detector interaction. In this case, you will never have the same probability space even with perfect detectors.

* The measurement time at given detector angles may a function of both the detector setting and the hidden variable λ, T(α,λ). If T is not a constant you could have a scenario in which for some combinations of setting and λ, the delays are too long that the pairing operation or (coincidence matching) eliminates some λs unfairly.

 

[billschnieder]

Ah, you're right, there's a bottomless supply of perplexity here

MorroBay was proposing a causal relationship between the observation at one station and the result at the other, and RoS is (for me, at least, and I expect some company here) a problem for that line of thinking.

What then does "non-locality" mean if it does not entail "causality"? What is the "mainstream-view" answer to this question?

 

[DevilsAvocado]

This is a red herring. If Alice an Bob have synchronized clocks, as they should/do in any such experiment,

And the reply is a blue parrot, synchronized clocks works only within a single inertial frame, unless you want to dispute SR also.

If one wants to do science, I believe one would like the theory to work in all, including difficult, situations. Not only in the living room.

 

[Maui]

And the reply is a blue parrot, synchronized clocks works only within a single inertial frame, unless you want to dispute SR also.

If one wants to do science, I believe one would like the theory to work in all, including difficult, situations. Not only in the living room.

Are you claiming that if I bury my head in the sand, the relativity of time will not go away?

 

[DrChinese]

Those terms being "determinism" and "local realism"? I wouldn't say that they are interchangeable. It just happens to be that for EPR correlations, there is no difference between the two.

Take out the word "local", and that's what I was saying...

 

[DrChinese]

Ah, you're right, there's a bottomless supply of perplexity here

MorroBay was proposing a causal relationship between the observation at one station and the result at the other, and RoS is (for me, at least, and I expect some company here) a problem for that line of thinking.

That's true too!

 

[DrChinese]

As Accardi proves in the paper cited at the beginning of this thread, the assumption that "the choice of the hidden variable is independent of the choice of settings of distant measurement devices" is the same as the assumption "that the random variables are defined on the same probability space" and that is the only other assumption assumption required to obtain the inequalities together with the assumption of outcomes (+1, -1).
Note that what most people call the "realism assumption", or the "counterfactual definiteness" assumption, are simply variants of this assumption, albeit while using non-standard definitions of "realism" or "CFD". Accardi has distilled it down to the essential mathematical assumption and clearly reveals that you do not need any physical assumption to obtain the inequalities.

You need another source for this statement. That paper is not acceptable by forum standards.

 

[audioloop]

I don't see that counterfactual definiteness is that important, .

i concur.
they bloated it to non realism.
realism is more than definite values.

 

[DevilsAvocado]

Are you claiming that if I bury my head in the sand, the relativity of time will not go away?

Ahh! The Stop Analyzing Next Difficulty experiment!
Of course you're right. Did a quick check and found the preliminary results from The Nevada Synchronized Counter Intuitive Experiment:

Bob (sponsored by Taco Bell) looking for the ground breaking results

 

[DevilsAvocado]

MorroBay was proposing a causal relationship

Who the h**l is MorroBay??

Googled Bell MorroBay causal and got Lolo's Mexican Food - Morro Bay, CA – Yelp??


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[Dale]

My apologies for not closing this sooner.