Bell's theorem

DrChinese

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You have to understand that in a CA there are no free parameters. Everything is related to everything else. The fact that Alice "decides" to make a "meta-choice" is quite irrelevant. Her state was already related to that baseball game and to the Bob's juggler, and to whatever you may think of. It might look somehow unintuitive, but this feature is shared with very respectable physical theories, like general relativity or classical electrodynamics.

...

The fact that was forgotten was that, at the beginning of the experiment, the states of the two planets (together with the local space curvature) were correlated already, and they have been so since the Big-Bang.

So, the states of Alice and Bob and of the particle source, baseball players, and of the juggler are correlated even before the experiment begins. An they will remain so.
First, your counter-example fails the locality loophole test. A shift of position of an object outside the light cone of a gravitational detector will not present the correlations of one which is quantum non-local. Relativistic dynamics are, of course, strictly local.

Second, the question is not whether there is a correlation (when such is asserted and assumed), but exactly how is the "answer" being supplied after an interaction with the environment? Ie. how is it that the entangled partner "knows" to give a spin up response 75% of the time when a distant spin partner is planning a spin down response after a last second angle setting instruction is received? The point being that a superdeterministic theory must have a explanation of how it is "more complete" than QM.

All I am hearing is that playbooks are *hidden* inside every particle and have *all* the answers with no logical explanation of how that occurs.
 
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No, that's not true. The evolution of a classical field does not depend on knowing what's happening in distant regions of spacetime. Classical E&M is not superdeterministic. It's local and deterministic.
1. If you make the states of the CA to correspond to those of an electromagnetic field, you get a discrete approximation to classical electrodynamics.

2. The local value of the field does depend on the position/momenta of all field sources (point charges) in the universe.

Assume a universe which only contains point-charges which is completely described by classical electromagnetism.

The trajectory of any charge is determined by the local em field (Lorentz force).
The local em field is a function of all charges' positions and momenta.

It follows that the trajectory of any charge is a function of all other charges' positions and momenta. Therefore the assumption that there exists an object (a charge or a group of charges) that evolves independently of the rest of the charges in the universe is false. In other words, the freedom/free-will/statistical independence assumption of Bell's theorem is false.

A similar reasoning applies to general relativity, you only need to replace point charges by point masses and local em field by space curvature. Freedom assumption is also false in a universe described by GR.
 

stevendaryl

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1. If you make the states of the CA to correspond to those of an electromagnetic field, you get a discrete approximation to classical electrodynamics.

2. The local value of the field does depend on the position/momenta of all field sources (point charges) in the universe.
No, it doesn't. The coupled Maxwell-Lorentz equations are local. What that implies is that if you want to compute [itex]\vec{E}(\vec{r},t)[/itex], it is sufficient to know the values of [itex]\vec{E}, \vec{B}[/itex] and the positions of charged particles in the region of spacetime consisting of all points [itex]\vec{r'}, t'[/itex] such that
  • [itex]0 < t - t' < \delta t[/itex],
  • [itex]|\vec{r'}-\vec{r}| < c \delta t[/itex].

You don't need to know anything about points more distant than [itex]c \delta t[/itex]. The evolution of the electric field only depends on facts about local conditions, not facts about the whole universe.

Assume a universe which only contains point-charges which is completely described by classical electromagnetism.

The trajectory of any charge is determined by the local em field (Lorentz force).
The local em field is a function of all charges' positions and momenta.
That's not true. The trajectory of a charge depends on local values of the fields. The evolution of the fields depends only on NEARBY charges. Distant charges are irrelevant (if you know the local values of fields in the recent past).

It follows that the trajectory of any charge is a function of all other charges' positions and momenta. Therefore the assumption that there exists an object (a charge or a group of charges) that evolves independently of the rest of the charges in the universe is false. In other words, the freedom/free-will/statistical independence assumption of Bell's theorem is false.
That's just not true. You're glossing the distinction between a local theory and a nonlocal theory.
 

DrChinese

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It follows that the trajectory of any charge is a function of all other charges' positions and momenta. Therefore the assumption that there exists an object (a charge or a group of charges) that evolves independently of the rest of the charges in the universe is false. In other words, the freedom/free-will/statistical independence assumption of Bell's theorem is false.
Sorry, one does not follow from the other.

In a local classical universe, you are saying that everything is predetermined. Perhaps. But that is a far cry from the superdeterminisitic universe you (or t' Hooft) are describing. In one, a decision to perform a particular measurement, while predetermined, has no bearing on the purely local outcomes. In the other, it does and that has the effect of returning results at odds with the "true" statistics and instead consistent with QM predictions (which are otherwise wrong).
 

Barry911

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Since when does non-locality equate with "no objective reality"?
 
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First, your counter-example fails the locality loophole test. A shift of position of an object outside the light cone of a gravitational detector will not present the correlations of one which is quantum non-local. Relativistic dynamics are, of course, strictly local.
It was not my intention to make such a claim.

Second, the question is not whether there is a correlation (when such is asserted and assumed), but exactly how is the "answer" being supplied after an interaction with the environment? Ie. how is it that the entangled partner "knows" to give a spin up response 75% of the time when a distant spin partner is planning a spin down response after a last second angle setting instruction is received? The point being that a superdeterministic theory must have a explanation of how it is "more complete" than QM.
I'll give you my take on this matter, using as an example classical electromagnetism.

1. Assume a universe which only contains point-charges which is completely described by classical electromagnetism.

2. I use a simple model of a "pre-entangled" pair: two rotating, classical, oppositely charged spheres. The spin is the classical magnetic moment associated with the rotation of each sphere.

3. The position/momenta of all charges in the universe in the past (including those of the would-be detectors) determines the local EM field near the "pre-entangled" pair.

4. When the EM force generated by the local EM field is strong enough, the spheres will depart, reaching the detectors.

5. The actual orientation of the spin magnetic moment of each sphere depends on the local EM field at the moment of the splitting.

6. From (3) and (5) it follows that the actual orientation of the spin magnetic moment of each sphere depends on the position/momenta of all charges in the universe in the past (including those of the would-be detectors).

7. The entire universe is deterministic, therefore the position/momenta of all charges in the universe in the future (say at the moment of detection) is a function of the position/momenta of all charges in the universe in the past.

8. From (6) and (7) it follows that the spin magnetic moment of each sphere and the position/momenta of all charges in the universe in the future at the moment of detection are not independent parameters.

9. The detector orientation at the time of measurement is nothing but the position/momenta of the charges that constitute the detector.

10. From (8) and (9) it follows that the spin magnetic moment of each sphere and the detector orientation at the time of measurement are not independent parameters.

I hope the point above can give you a "feeling" of how local but deterministic theories can provide correlations in Bell tests.

All I am hearing is that playbooks are *hidden* inside every particle and have *all* the answers with no logical explanation of how that occurs.
Not from me.
 

stevendaryl

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I'll give you my take on this matter, using as an example classical electromagnetism.

1. Assume a universe which only contains point-charges which is completely described by classical electromagnetism.

2. I use a simple model of a "pre-entangled" pair: two rotating, classical, oppositely charged spheres. The spin is the classical magnetic moment associated with the rotation of each sphere.

3. The position/momenta of all charges in the universe in the past (including those of the would-be detectors) determines the local EM field near the "pre-entangled" pair.

4. When the EM force generated by the local EM field is strong enough, the spheres will depart, reaching the detectors.

5. The actual orientation of the spin magnetic moment of each sphere depends on the local EM field at the moment of the splitting.
But that isn't good enough. The relevant facts about the detectors is not their positions at the time of splitting. What's relevant for the predictions of QM are the positions of the detectors at the time of detection. The detectors could very well change positions while the particles are in-flight (after they have split).

It is true that if you knew the positions and velocities of every particle in the universe, then you could in principle predict the positions the detectors would be in at the time of detection. But that's a LOT more complicated than allowing the actual orientation of the spin magnetic moment todependon the local EM field at the moment of splitting. As a matter of fact, the local EM field would be pretty much irrelevant. (If the detectors are electrically neutral, then they have a negligible effect on a distant EM field.) What it would take for a local deterministic model to reproduce the predictions of quantum mechanics is a supercomputer that can simulate the rest of the universe. And it would have to come up with the result of its computation essentially instantly.

This approach seems completely implausible to me.
 

DrChinese

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... I hope the point above can give you a "feeling" of how local but deterministic theories can provide correlations in Bell tests.
Most definitely not, and we know that from Bell! Certainly there are many more things that determine and ultimately affect the outcomes of experiments in a local classical (deterministic) universe. The orientation of angle settings, for example. The orientation of a particle is not determined in any way by randomizing devices which select settings those outside of a light cone, as was done in the experiment of Weihs et al (1998).

The point is that superdeterminism is NOT anything like any Laplacian demon operating in a clockwork universe. In such a universe, we would not get a value from experiment that matches QM. In superdeterminism, there is a mechanism in place that PREVENTS the selected sample from matching the true universe of counterfactual values. And I say that NO superdeterministic theory can ever reproduce all of the results of QM.

Of course, I can't prove that a la Bell - but it wouldn't surprise me if someone else could eventually. I do not believe that ANY program a la t' Hooft's CA can ever succeed. The only superdeterministic program that can succeed, in my opinion, is one in which:

a) There is a (VERY large) playbook handed out to every particle in the universe as it created.
b) This playbook must be created ex nihilo since even photons from a laser beam have their own unique copies.
c) There is an absolute time reference frame in the entire universe. This is required to that Bell test results can synchronize properly.
d) That playbook instructs particles how to answer for their quantum observables at all times, including during Bell tests. So fundamental particles such as electrons will be guided by the playbook for a very, very, very long time (which is why the playbook is VERY large).
e) And of course, the playbook is safely hidden inside every particle, along with the clock used to determine which page of the playbook is to be referenced at any moment.
f) The only apparent purpose of all these playbooks is to get around Bell's Theorem. Apparently, J.S. Bell is actually the most important being in all history since the playbook is a giant conspiracy to disprove his theorem. (This is humor.)

So a playbook might look like this:

Playbook for electron 21ZNA9-004958:
...
August 10, 4:11:34.00599834: Act spin up in X direction.
August 10, 4:11:34.00601577: Act spin down in Y direction.
August 10, 4:11:34.00624384: Act spin up in Z direction.
August 10, 4:11:34.00653403: Emit a photon and give it a playbook of its own, presumably copied from the electron's playbook.
...
 

stevendaryl

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I do not believe that ANY program a la t' Hooft's CA can ever succeed. The only superdeterministic program that can succeed, in my opinion, is one in which: [deleted]
Well, the playbook idea that you sketched could be implemented by one of t'Hooft's machines, couldn't it?
 

DrChinese

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Well, the playbook idea that you sketched could be implemented by one of t'Hooft's machines, couldn't it?
Unless his machine is a "Bell Playbook Reader" like a Kindle, I doubt it. Because anything less can probably be falsified as it will rely on some element which is not hidden. That makes it susceptible to experimental falsification. Which I would expect to be "easy" to do, in the theoretical sense.
 
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No, it doesn't. The coupled Maxwell-Lorentz equations are local. What that implies is that if you want to compute [itex]\vec{E}(\vec{r},t)[/itex], it is sufficient to know the values of [itex]\vec{E}, \vec{B}[/itex] and the positions of charged particles in the region of spacetime consisting of all points [itex]\vec{r'}, t'[/itex] such that
  • [itex]0 < t - t' < \delta t[/itex],
  • [itex]|\vec{r'}-\vec{r}| < c \delta t[/itex].

You don't need to know anything about points more distant than [itex]c \delta t[/itex]. The evolution of the electric field only depends on facts about local conditions, not facts about the whole universe.
Sure, but you forget that the local values of electric and magnetic field are related to their far-away sources. If you know the field in your location, true, you don't need to know about the field sources (distant charges). But this does not imply in any way that the local field is independent of its distant sources. It's your choice to either measure the local field directly or compute it from position/momenta of nearby and distant charges. You don't need both, it will be redundant.

That's not true. The trajectory of a charge depends on local values of the fields. The evolution of the fields depends only on NEARBY charges. Distant charges are irrelevant (if you know the local values of fields in the recent past).
But, as I've pointed above, "the local values of fields in the recent past" is a function of position/momenta of all field sources (in the past). So, the trajectory of a charge is not independent from the position/momenta of all the other charges.

From the fact that the theory is deterministic it also follows that the future position/momenta of all charges is a function of position/momenta of all charges in the past.

We can therefore conclude that the trajectory of a charge is also not independent from the position/momenta of all the other charges in the future.

That's just not true. You're glossing the distinction between a local theory and a nonlocal theory.
I think I have clearly pointed out where your reasoning fails. It becomes obvious if you think in terms of gravity. GR is local, therefore you can predict Earth's trajectory if you know the space curvature in its vicinity. You do not need to know anything about the Sun, Moon or any other object. But this doesn't imply that Earth's trajectory is independent of the Sun. And the reason is that the local curvature itself DOES depend on the Sun.
 
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But that isn't good enough. The relevant facts about the detectors is not their positions at the time of splitting. What's relevant for the predictions of QM are the positions of the detectors at the time of detection. The detectors could very well change positions while the particles are in-flight (after they have split).
As i have argued above, once you establish that the spin of the particles depends on the past position/momenta of all the other charges it follows that it also depends on their future position/momenta due to determinism.

It is true that if you knew the positions and velocities of every particle in the universe, then you could in principle predict the positions the detectors would be in at the time of detection. But that's a LOT more complicated than allowing the actual orientation of the spin magnetic moment to depend on the local EM field at the moment of splitting. As a matter of fact, the local EM field would be pretty much irrelevant. (If the detectors are electrically neutral, then they have a negligible effect on a distant EM field.) What it would take for a local deterministic model to reproduce the predictions of quantum mechanics is a supercomputer that can simulate the rest of the universe. And it would have to come up with the result of its computation essentially instantly.

This approach seems completely implausible to me.
First of all, do you agree that the freedom assumption fails for classical EM?
 
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Most definitely not, and we know that from Bell! Certainly there are many more things that determine and ultimately affect the outcomes of experiments in a local classical (deterministic) universe. The orientation of angle settings, for example. The orientation of a particle is not determined in any way by randomizing devices which select settings those outside of a light cone, as was done in the experiment of Weihs et al (1998).

The point is that superdeterminism is NOT anything like any Laplacian demon operating in a clockwork universe. In such a universe, we would not get a value from experiment that matches QM. In superdeterminism, there is a mechanism in place that PREVENTS the selected sample from matching the true universe of counterfactual values. And I say that NO superdeterministic theory can ever reproduce all of the results of QM.
Can I ask you to point out exactly where my argument fails? Which of the points I've made (1-10) are false in your opinion? I know your opinion is different, but you have to justify it with arguments. If you want to use Bell again you have to point out why my argument against the freedom assumption fails.
 

stevendaryl

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Sure, but you forget that the local values of electric and magnetic field are related to their far-away sources. If you know the field in your location, true, you don't need to know about the field sources (distant charges). But this does not imply in any way that the local field is independent of its distant sources. It's your choice to either measure the local field directly or compute it from position/momenta of nearby and distant charges. You don't need both, it will be redundant.
That's true. Everything can affect everything else. But the point of a local theory is that everything that's relevant about distant particles and fields is already captured in the values of local fields and the positions/momenta of local particles. So the evolution equations don't need to take into account anything other than local conditions.

This is in contrast to a nonlocal theory, where the evolution equations must potentially take into account everything. Superdeterminism can turn a nonlocal theory into a local theory, but at the cost of requiring, essentially, a local representation of distant facts. The normal electromagnetic fields do not have anywhere near enough information to reproduce nonlocal EPR correlations.

But, as I've pointed above, "the local values of fields in the recent past" is a function of position/momenta of all field sources (in the past).
I think that's a very bad way of thinking about it. The evolution equations for the E&M field do not require any knowledge about distant particles and fields. Everything of relevance about distant variables is already included in the values of local variables.

The reason I say that it is a bad way of thinking about it is that glosses over the very important distinction between local and nonlocal theories.

I think I have clearly pointed out where your reasoning fails. It becomes obvious if you think in terms of gravity. GR is local, therefore you can predict Earth's trajectory if you know the space curvature in its vicinity. You do not need to know anything about the Sun, Moon or any other object. But this doesn't imply that Earth's trajectory is independent of the Sun. And the reason is that the local curvature itself DOES depend on the Sun.
You keep wanting to make things abstract, but I don't see how the abstraction gives any insight. Yes, everything depends on everything else, but in the case of gravity, the dependencies are very constrained. In the case of an EPR-type experiment, the dependencies are completely unconstrained. In such an experiment, Alice chooses a detector orientation, [itex]\vec{a}[/itex] and Bob chooses a detector orientation, [itex]\vec{b}[/itex] and the particle detected by Alice must choose to go right or left (in a Stern-Gerlach set-up), and similarly for the particle detected by Bob. In order for a deterministic model to generate the correct statistics (those predicted by QM), it seems that each particle's decision must depend on BOTH [itex]\vec{a}[/itex] and [itex]\vec{b}[/itex]. So the question is: how does Bob's particle know the value of [itex]\vec{a}[/itex], and how does Alice's particle know the value of [itex]\vec{b}[/itex]?

Your answer seems to be: Alice's state was known ahead of time, and her choice of [itex]\vec{a}[/itex] was (by assumption) deterministic, so [itex]\vec{a}[/itex] is actually computable from this knowledge. But it's not just knowledge about Alice. Since Alice can make her decision based on who gets a hit in the baseball game, the computation would have to involve the states of the baseball players, as well. And since a fan at the baseball game might throw a paper airplane to distract the batter, you would have to know the state of the fans, as well. The computation is completely unconstrained, in that it might require knowledge of the whole rest of the universe.

You give the analogy of the position of the Earth in the future. Well, there is always the possibility that the Moon will explode and fragments will knock the Earth off its course. Then our prediction would be wrong. Positions of planets are only predictable under the assumption that nothing too weird is going to happen. If we tried to take into account weird stuff, then the future position of the Earth would not be predictable, in any practical sense. It would be computationally impossible.

The same thing would apply to an EPR type experiment. There might be a way to guess the most likely setting Alice will choose, based on incomplete knowledge of Alice. But to be certain of Alice's choice would be computationally impossible (given finite resources to do the computation). So if EPR correlations were explained by superdeterminism, it would either require infinite precision and infinite processing power in the little cellular automata, or else the correlations could be destroyed by Alice using a sufficiently difficult-to-predict algorithm for choosing her setting.

Essentially, the only way that the EPR correlations could always hold is if every particle has a complete description of the whole rest of the universe, and the processing power to simulate the future evolution of the universe.

But there is no reason to argue about it: If you really believe that a superdeterministic theory can reproduce the predictions of quantum mechanics, then try to create one. It's basically the quantum Randi challenge:

We have two teams: The Red Team and the Blue Team. The Red Team gets to pick algorithms for Alice and Bob to decide their settings. The Blue Team gets to pick an algorithm for the electron and positron to decide whether they go left or right. Can the Blue Team reproduce the statistics predicted by QM?

In a superdeterministic model, the Blue Team would be able to know the algorithms chosen by the Red Team. But what is the Blue Team going to do with this knowledge? It could try simulating the running of the Red Team algorithms, in order to predict what the settings will be. That would work, but it would require the Blue Team to have potentially unlimited processing power.
 

stevendaryl

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First of all, do you agree that the freedom assumption fails for classical EM?
No, I don't. You cannot determine the positions and momenta of distant particles knowing only local fields.
 

stevendaryl

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Can I ask you to point out exactly where my argument fails? Which of the points I've made (1-10) are false in your opinion? I know your opinion is different, but you have to justify it with arguments. If you want to use Bell again you have to point out why my argument against the freedom assumption fails.
I don't think that there is any doubt that everything in the universe is correlated with everything else. That's not the question. The question is whether that correlation is strong enough that the locations of distant particles can be computed using only local knowledge.
 

atyy

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In Bell's theorem there's a "free will" assumption, which means we assume that measurements settings at spacelike separation can be set independently (in the probabilistic sense). Is "superdeterminism" different from saying that the free will assumption fails?
 

stevendaryl

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Unless his machine is a "Bell Playbook Reader" like a Kindle, I doubt it. Because anything less can probably be falsified as it will rely on some element which is not hidden. That makes it susceptible to experimental falsification. Which I would expect to be "easy" to do, in the theoretical sense.
I'm saying that a "Bell Playbook Reader" could very well be implemented as a cellular automaton, couldn't it?

If Alice's and Bob's settings could be known ahead of time, then it would not be difficult to reproduce the QM predictions for EPR using local hidden variables. If the universe is deterministic, then whatever mechanism chooses the hidden variables could, in principle, predict Alice's and Bob's settings from past information. I think that's a ridiculous model, but I don't think it's logically impossible.

Actually, now that I think about it, this kind of deterministic model for EPR reminds me a little bit of the Bohm model. In the latter case, nonlocal interactions are introduced to make the statistics work out, but it's assumed that there are no observable nonlocal interactions. In the case of the playbook reader, potentially unlimited computing power is introduced to make the statistics work out, but it's assumed that this computing power is unavailable for any other purpose. (If Alice tapped into that kind of computing power to make a pseudo-random choice, then that would defeat the ability to predict Alice's setting. A computer can't, in real time, predict the behavior of an equally powerful computer.)
 

DrChinese

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Can I ask you to point out exactly where my argument fails? Which of the points I've made (1-10) are false in your opinion? I know your opinion is different, but you have to justify it with arguments. If you want to use Bell again you have to point out why my argument against the freedom assumption fails.
Well sure, and I don't think this path is new. :smile: Bell is well accepted after all.

According to you, and assuming there is some classical action (local and realistic), there are correlations between events that are separated. Even in classical determinism, I say there are NOT mechanisms which relate observables used in Bell tests.

Now I get the idea that a planet follows a distinct orbit around a star, and that is pre-determined even though the planet and the star are spacelike separated. Thus a prediction can be made with certainty on the path of the planet and of the star even if a decision is made as to how to observe each at the last possible time. The results seem observer independent. But they are not actually non-local. And if there is any interaction between the observer and that being observed which is material to the outcome, then that part of your argument explicitly fails. I forget which number that is.

Regardless, in a deterministic world, such correlations are extremely limited. They certainly don't lead to predictions for Bell tests that match experiment. That such is true is seen by asking: why don't classical dice correlate more than by chance (on the average, 1 of 6 times a pair will match) ? You are saying that there is a stochastic connection, and yet that is picked out of the blue. There is no hypothetical connection between the observer's choice of measurement that restricts him or her or otherwise guides the results. You need *Superdeterminism* for that!
 

stevendaryl

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In Bell's theorem there's a "free will" assumption, which means we assume that measurements settings at spacelike separation can be set independently (in the probabilistic sense). Is "superdeterminism" different from saying that the free will assumption fails?
That's what superdeterminism means, in practice.

However, I don't think that the assumption of "free will" is necessary. The real assumption is that the algorithms (whatever they are) for choosing the settings are too complicated to be predictable by any single mechanism in whatever is supposed to choose the hidden variable values. The settings might be deterministic, but they can depend on absolutely anything (as I said, they could depend on events from a baseball game, or anything else). So the only way that the settings could be guaranteed to be predictable is if the mechanism that chooses the hidden variable had access to a complete simulation of the universe (or at least of everything in the region surrounding the experiment).
 

atyy

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That's what superdeterminism means, in practice.

However, I don't think that the assumption of "free will" is necessary. The real assumption is that the algorithms (whatever they are) for choosing the settings are too complicated to be predictable by any single mechanism in whatever is supposed to choose the hidden variable values. The settings might be deterministic, but they can depend on absolutely anything (as I said, they could depend on events from a baseball game, or anything else). So the only way that the settings could be guaranteed to be predictable is if the mechanism that chooses the hidden variable had access to a complete simulation of the universe (or at least of everything in the region surrounding the experiment).
The assumption of "free will" is necessary. For example, the assumption of independence could fail with fine tuning of initial conditions, since the apparently independent apparatuses were at the same location at the big bang.
 

stevendaryl

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The assumption of "free will" is necessary. For example, the assumption of independence could fail with fine tuning of initial conditions, since the apparently independent apparatuses were at the same location at the big bang.
I perfectly well understand that fine tuning of initial conditions can theoretically explain everything. However, it's a very unsatisfactory satisfaction: As Dr. Chinese said, you have to carefully choose, at the beginning of time, the precise values for all positions and momenta just to make Bell's inequalities work out. Such fine tuning is certainly a logically possible explanation, but variants of such fine tuning could explain absolutely everything. All the experiments ever purported to demonstrated relativity or QM could very well be just freak malfunctions of equipment that just happen to malfunction in just the right way to seem to agree with the theoretical predictions. Invoking fine-tuning to explain EPR correlations is not much (if any) more satisfying than that.
 

stevendaryl

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I perfectly well understand that fine tuning of initial conditions can theoretically explain everything. However, it's a very unsatisfactory satisfaction: As Dr. Chinese said, you have to carefully choose, at the beginning of time, the precise values for all positions and momenta just to make Bell's inequalities work out. Such fine tuning is certainly a logically possible explanation, but variants of such fine tuning could explain absolutely everything. All the experiments ever purported to demonstrated relativity or QM could very well be just freak malfunctions of equipment that just happen to malfunction in just the right way to seem to agree with the theoretical predictions. Invoking fine-tuning to explain EPR correlations is not much (if any) more satisfying than that.
So, I don't think that invoking "free will" is a very good way to look at things. We don't really have any idea what "free will" means. Its only role in arguments about Bell is that it is something that is not predictable. To me, rejection of superdeterminism is not really about free will. It's about the rejection of a class of theories that are logically possible, but are useless because they explain too much. Variations could be used to explain absolutely anything at all.

On the other hand, if there were a superdeterministic theory that explained HOW the fine-tuning came about, I would find that more satisfying.
 

atyy

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I perfectly well understand that fine tuning of initial conditions can theoretically explain everything. However, it's a very unsatisfactory satisfaction: As Dr. Chinese said, you have to carefully choose, at the beginning of time, the precise values for all positions and momenta just to make Bell's inequalities work out. Such fine tuning is certainly a logically possible explanation, but variants of such fine tuning could explain absolutely everything. All the experiments ever purported to demonstrated relativity or QM could very well be just freak malfunctions of equipment that just happen to malfunction in just the right way to seem to agree with the theoretical predictions. Invoking fine-tuning to explain EPR correlations is not much (if any) more satisfying than that.
Well if it's a loophole it's a loophole. Much more important than aesthetic satisfactoriness is we cannot devise a superdeterministic theory that can be used by us to describe our universe, since we don't have access to such fine grained data to determine the fine tuned initial condition.

Edit: Unless the dynamics and fine tuned initial condition were both compact enough, and were fine tuned to be placed in 't Hooft's head too.
 

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