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Hi. I'm not a physicist, but I’m intrigued by Bell's theorem and I've been stumbling with "superdeterminism." My understanding of the concept is that everything is not just predetermined, but the initial conditions of the universe are fine-tuned and "conspire" so choices of which versions of Bell test experiments to perform and which measurement settings to use are highly correlated with the variable being measured and can’t be made statistically independent in any way (guided by *any* process by which one might attempt to inject functional randomness -- consciousness, Brownian motion, any kind of PRNG, etc.), so that conscious beings performing Bell test experiments always get biased samples producing the wrong results, and a false picture of physics seeming to match QM even though reality is truly described by a local hidden variable theory. I'm trying to figure out if this is REALLY how bad it is, or is there any more to it?

Because this is, of course, completely at odds with what I originally read because half the sources I read equate it to determinism but then claim it somehow evades Bell. There’s a LOT of misinformation and this subject seems to really attract a lot of cranks, and because I've seen disputing claims on basically everything, I have a few questions.

1. Bell proves a local hidden variable theory would imply an inequality so that the correlations between two entangled spin measurements are essentially a linear function of the angle difference, and this inequality contradicts the one predicted by QM. Is it correct that since a "local hidden variable theory" is taken to be an *extension* of QM (in the original EPR context), and two different predictions are given for the correlations, this would mean such a "local hidden variable theory" wouldn’t just disagree with QM but be logically contradictory (unless Bell's inequalities don't hold)? (Or am I wrong, and that value for QM is only the one for "QM without hidden variables?")

2. Exactly how is superdeterminism supposed to be a “loophole?” Is it that a) We can't derive Bell’s inequality; the argument doesn't go through without assuming of statistical independence, so it IS possible for a superdeterministic local HVT to predict the same correlations as QM, or b) It's a loophole in Bell test experiments. Bell’s theorem still holds, but the highly robust observed violation of Bell's inequalities in our universe (and confirmation of QM) is illusory. For some angle between detectors, if the QM-predicted correlation is 25%, and the observed correlation is very close to 25%, but the correlation predicted by a local hidden variable theory is 33%, the correlation actually IS 33% in the universe. Local HVTs can only produce the QM predicted correlations by chance, and these would have to vanish with a sufficiently large unbiased, randomized sample; the universe just “conspires” to deceive us that QM is true. Even though “superdeterminism” is purported to allow, create, and explain away exceedingly unlikely statistical occurrences, systematic biases, and conspiracies already in things like spin correlations, those biases do have to be evened out in sufficiently large samples and couldn't be a universal thing. Superdeterminism couldn't actually make it so the actual correlation is 25% while preserving local realism; or c) both of those?

3. Does superdeterminism negate counterfactual definiteness? WP claims that since under superdeterminism it would be technically impossible to perform a different experiment, this negates CFD and that therefore the argument for Bell’s inequalities doesn’t go through. If that's correct, don't all deterministic theories negate CFD? This is very confusing to me because what I'm read elsewhere is invalidating CFD means invalidating realism (which it’s almost synonymous with) and determinism. And wouldn’t it invalidate superdeterminism too? How could getting rid of CFD recover realism; that seems backwards? Or is it just because of determinism? That seems to make no sense because regular determinism doesn't save local HVTs

4. Is the “conspiratorial” quality essential to superdeterminism? Instead of “superdeterminism” just being used to fine-tune selection of experimental settings for Bell tests to be performed by conscious experimenters, suppose it's predetermined that for all similar observations/ measurements in the universe, not just those directly observed by conscious experimenters, the correlations will mimic QM's predictions, and generally physical interactions would give the statistical appearance of QM even though reality is local realist; the universe always "pretends" to violate local realism even in all interactions not observed (even indirectly) by conscious experimenters. Could that be a possibility under a "superdeterministic" account? If even possible, it would be highly implausible and artificial, probably require new physics and every particle containing hidden variables with information about every particle in the universe, be horrible unfalsifiable, unscientific, violate occam's razor and 300 other heuristic principles, and just be downright terrible (and I feel silly for even proposing it) but at the very least avoid the most insane (to me at least) aspect of superdeterminism -- that the universe would arbitrarily, selectively only "fake" QM for measurements in experiments performed by conscious experimenters in order to systematically misrepresent the true result, and therefore would have to apparently "know" the difference between general physical interactions and ones that are part of experiments that conscious experimenters are going to reason from, and make some "cutoff" between measurements that are part of experiments and that aren't. I don't know if what I've said here made any sense, but my point is it's not clear to me (though there's probably a simple reason) why superdeterminism would NEED to be conspiratorial.

5. People espousing superdeterminism tend to either INSIST despite all evidence that superdeterminism = determinism, or, less often, recognize the difference but say their version of superdeterminism avoids a conspiracy, that "all I'm saying is that the measurement settings are correlated with the variable, somehow saving local realism" but fail to actually elaborate on the specifics of how that would work or be different, or to fully construct a workable theory based on this. t'Hooft seems to be the only mainstream physicist who's really worked on this. Do his proposals end up with a form of superdeterminism that avoids "conspiracy" in some way (I can't imagine him, or anyone, actually being a proponent of the crazy version)?

I think other than the low quality of resources on this subject, the main thing I'm lacking is an understanding of why even in the case of superdeterminism (which means we're entertaining the possibility of the universe being predetermined to cause exceedingly unlikely events) the universe must still on a large scale reproduce the correlations predicted by LHVTs (i have a feeling it's a really simple explanation though). I'm going off the derivation of Bell’s original inequality that is outlined on the Bell’s Theorem article on Wikipedia and I can mostly follow it but I also don't know whether Bell's inequality holds even without statistical independence.

Any help is much appreciated, and I have a couple follow-up questions if that's okay, and I apologize if this is too much or these kinds of questions don't belong; I lack a lot of knowledge of physics so there are probably really simple answers but I'm trying my best to understand. Thanks all, and thanks to anyone who read ^^

Because this is, of course, completely at odds with what I originally read because half the sources I read equate it to determinism but then claim it somehow evades Bell. There’s a LOT of misinformation and this subject seems to really attract a lot of cranks, and because I've seen disputing claims on basically everything, I have a few questions.

1. Bell proves a local hidden variable theory would imply an inequality so that the correlations between two entangled spin measurements are essentially a linear function of the angle difference, and this inequality contradicts the one predicted by QM. Is it correct that since a "local hidden variable theory" is taken to be an *extension* of QM (in the original EPR context), and two different predictions are given for the correlations, this would mean such a "local hidden variable theory" wouldn’t just disagree with QM but be logically contradictory (unless Bell's inequalities don't hold)? (Or am I wrong, and that value for QM is only the one for "QM without hidden variables?")

2. Exactly how is superdeterminism supposed to be a “loophole?” Is it that a) We can't derive Bell’s inequality; the argument doesn't go through without assuming of statistical independence, so it IS possible for a superdeterministic local HVT to predict the same correlations as QM, or b) It's a loophole in Bell test experiments. Bell’s theorem still holds, but the highly robust observed violation of Bell's inequalities in our universe (and confirmation of QM) is illusory. For some angle between detectors, if the QM-predicted correlation is 25%, and the observed correlation is very close to 25%, but the correlation predicted by a local hidden variable theory is 33%, the correlation actually IS 33% in the universe. Local HVTs can only produce the QM predicted correlations by chance, and these would have to vanish with a sufficiently large unbiased, randomized sample; the universe just “conspires” to deceive us that QM is true. Even though “superdeterminism” is purported to allow, create, and explain away exceedingly unlikely statistical occurrences, systematic biases, and conspiracies already in things like spin correlations, those biases do have to be evened out in sufficiently large samples and couldn't be a universal thing. Superdeterminism couldn't actually make it so the actual correlation is 25% while preserving local realism; or c) both of those?

3. Does superdeterminism negate counterfactual definiteness? WP claims that since under superdeterminism it would be technically impossible to perform a different experiment, this negates CFD and that therefore the argument for Bell’s inequalities doesn’t go through. If that's correct, don't all deterministic theories negate CFD? This is very confusing to me because what I'm read elsewhere is invalidating CFD means invalidating realism (which it’s almost synonymous with) and determinism. And wouldn’t it invalidate superdeterminism too? How could getting rid of CFD recover realism; that seems backwards? Or is it just because of determinism? That seems to make no sense because regular determinism doesn't save local HVTs

4. Is the “conspiratorial” quality essential to superdeterminism? Instead of “superdeterminism” just being used to fine-tune selection of experimental settings for Bell tests to be performed by conscious experimenters, suppose it's predetermined that for all similar observations/ measurements in the universe, not just those directly observed by conscious experimenters, the correlations will mimic QM's predictions, and generally physical interactions would give the statistical appearance of QM even though reality is local realist; the universe always "pretends" to violate local realism even in all interactions not observed (even indirectly) by conscious experimenters. Could that be a possibility under a "superdeterministic" account? If even possible, it would be highly implausible and artificial, probably require new physics and every particle containing hidden variables with information about every particle in the universe, be horrible unfalsifiable, unscientific, violate occam's razor and 300 other heuristic principles, and just be downright terrible (and I feel silly for even proposing it) but at the very least avoid the most insane (to me at least) aspect of superdeterminism -- that the universe would arbitrarily, selectively only "fake" QM for measurements in experiments performed by conscious experimenters in order to systematically misrepresent the true result, and therefore would have to apparently "know" the difference between general physical interactions and ones that are part of experiments that conscious experimenters are going to reason from, and make some "cutoff" between measurements that are part of experiments and that aren't. I don't know if what I've said here made any sense, but my point is it's not clear to me (though there's probably a simple reason) why superdeterminism would NEED to be conspiratorial.

5. People espousing superdeterminism tend to either INSIST despite all evidence that superdeterminism = determinism, or, less often, recognize the difference but say their version of superdeterminism avoids a conspiracy, that "all I'm saying is that the measurement settings are correlated with the variable, somehow saving local realism" but fail to actually elaborate on the specifics of how that would work or be different, or to fully construct a workable theory based on this. t'Hooft seems to be the only mainstream physicist who's really worked on this. Do his proposals end up with a form of superdeterminism that avoids "conspiracy" in some way (I can't imagine him, or anyone, actually being a proponent of the crazy version)?

I think other than the low quality of resources on this subject, the main thing I'm lacking is an understanding of why even in the case of superdeterminism (which means we're entertaining the possibility of the universe being predetermined to cause exceedingly unlikely events) the universe must still on a large scale reproduce the correlations predicted by LHVTs (i have a feeling it's a really simple explanation though). I'm going off the derivation of Bell’s original inequality that is outlined on the Bell’s Theorem article on Wikipedia and I can mostly follow it but I also don't know whether Bell's inequality holds even without statistical independence.

Any help is much appreciated, and I have a couple follow-up questions if that's okay, and I apologize if this is too much or these kinds of questions don't belong; I lack a lot of knowledge of physics so there are probably really simple answers but I'm trying my best to understand. Thanks all, and thanks to anyone who read ^^

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