't Hooft cellular automaton interpretation

[Heidi]

TL;DR Summary

how to describe the epr experiment with ontological states?

Hi Pfs,
I am not sure that understand what the ontological state in the r' Hooft interpretation: Is this correct: A particle is never in a superposition of ontological properties. it is not here> + there> there is no free will . if it is here> Bob will choose to measure its position , not its momentum and he will find the result "if is here>" we can have a source or maximally entangled particles with a null global momentum and spin projection in the mainstream point of view Bob and Alice share a uu + dd pair and choose 2 directions if Bob get u alice wil mesure the value on another direction of this u state. How to describe this in the deterninistic point of view? sometime the source will emit a uu pair sometime a dd pair along same directions and sometime u in the z direction and d in the x direction? How to describe the source to tell that it is maximally entangles with a null sum? i am not sure to be clear ... do you understand my problem?
thanks

Reference: https://www.physicsforums.com/forums/quantum-physics.62/post-thread

 

[PeterDonis]

Reference: https://www.physicsforums.com/forums/quantum-physics.62/post-thread

This is a link to the PF "post a new thread" page. Please give a corrected reference.

 

[DrChinese]

Given the t' Hooft "interpretation" is not accepted science, and does not actually model quantum mechanics: I would recommend a shift to the Interpretations subforum.

 

[PeterDonis]

I would recommend a shift to the Interpretations subforum.

Thread has been moved.

 

[Quantumental]

Given the t' Hooft "interpretation" is not accepted science, and does not actually model quantum mechanics: I would recommend a shift to the Interpretations subforum.

How does it not model QM compared to all other interpretations?

 

[DrChinese]

How does it not model QM compared to all other interpretations?

Well, here is as much as can really be said to be specific. You tell me what it models, because I say it models nothing - and certainly not QM.

https://arxiv.org/abs/1405.1548

From the abstract: "We explain how such thoughts can conceivably be reconciled with Bell's theorem, and how the usual objections voiced against the notion of `superdeterminism' can be overcome, at least in principle."

This is not an interpretation. It is an an outline of an idea for "further study" and nothing more. You cannot even point out the obvious problems with what is written, because any legitimate critique will be hand waived away.

 

[Demystifier]

It's not a problem to interpret EPR and other quantum phenomena with ontic and deterministic theory, the best known example is Bohmian mechanics. But people would like to have a local theory of that kind, and Bohmian mechanics is not local. That's why people try superdeterministic models (like cellular automaton), because they hope that with superdeterminism they can save locality. However, there are general arguments that local superdeterministic models that reproduce QM must be conspiratorial. Nevertheless, some authors (for instance, 't Hooft and Hossenfelder) have constructed non-conspiratorial superdeterministic models that reproduce QM. The catch is that those models are not local, which indeed is to be expected owing to the Bell theorem. But the authors claim that their models are local (I was even a referee for one such paper by 't Hooft). They are wrong, their non-conspiratorial models that reproduce QM are not local, but for some reason they don't understand it.

 

[gentzen]

... they hope that with superdeterminism they can save locality. However, there are general arguments that local superdeterministic models that reproduce QM must be conspiratorial. Nevertheless, some authors (for instance, 't Hooft and Hossenfelder) have constructed non-conspiratorial superdeterministic models that reproduce QM. The catch is that those models are not local, which indeed is to be expected owing to the Bell theorem. But the authors claim that their models are local (I was even a referee for one such paper by 't Hooft).

I also had the impression that 't Hooft claims that his models are local. But for Hossenfelder and Palmer, my impression was that they just don't care that their models are not local, that they don't try to claim that they are, and that for them, locality is not the problem to be solved by superdeterminism.

They are wrong, their non-conspiratorial models that reproduce QM are not local, but for some reason they don't understand it.

Or maybe they don't care (except for 't Hooft). Maybe it is just their opponents who are so convinced that locality must be their motivation, that they fail to even mention that their supposed counter-arguments implicitly assume a specific form of locality:

Can you prove this?

Isn't it obvious? We are talking about a lack of statistical independence between a photon source at A and light sources in two quasars, each a billion light-years from A in opposite directions. How else could that possibly be except by some kind of pre-existing correlation?

A proof normally relies on assumptions, and it is neither obvious which assumptions have been used here to arrive at that conclusion, nor which assumptions would make sense in the context of superdeterminism as a proposed solution for the measurement problem. If we assume determinism and Bell locality (factorizability), then maybe we can arrive at that conclusion. The "typical" superdeterministic model is indeed deterministic, but those able to reproduce the predictions of quantum mechanics don't seem to satisfy Bell locality. At least that was my impression from the models I have seen so far. Others apparently got a similar impression:

Super-determinism is super-nonlocal

 

[martinbn]

They are wrong, their non-conspiratorial models that reproduce QM are not local, but for some reason they don't understand it.

The reason why they don't understand it is very clear. The initial conditions for the universe are such that they lead to the formation of the solar system, earth, evolution of life, birth and brain developemnt of those people in such a way that they would write those papers and not understand whether their models are local or not.

 

[Demystifier]

But for Hossenfelder and Palmer, my impression was that they just don't care that their models are not local, that they don't try to claim that they are, and that for them, locality is not the problem to be solved by superdeterminism.

Or maybe they don't care (except for 't Hooft). Maybe it is just their opponents who are so convinced that locality must be their motivation, that they fail to even mention that their supposed counter-arguments implicitly assume a specific form of locality:

Maybe, but if locality is not their motivation, then why are they not satisfied with the Bohmian model?

Hossenfelder told me that one of her motivations is Lorentz covariance and that she doesn't like Bohmian model because it's not Lorentz covariant. But Bohmian model is not Lorentz covariant precisely because it is not local, I'm not sure whether she is aware of that or not.

Another Hossenfelder's motivation, which makes more sense, is that she wants to make new measurable predictions, not just to reproduce the old ones, which makes Bohmian model uninteresting.

 

[WernerQH]

How to describe this in the deterninistic point of view?

I suspect you'll never get an answer.

Common sense demands an explanation for correlations, not their absence. But faced with Bell's theorem, superdeterminists feel forced to give up probability theory in a desperate and silly attempt to uphold locality and determinism. Superdeterminists think that physics ought to be local and deterministic. For them these classical preconceptions carry more weight than common sense.

Of course they deny that they reject probability theory. It would mean giving up most of science! The detector settings in a Bell-type experiment could be chosen to depend on the digits of pi, and you can get different random sequences if you start with the umpteenth billionth digit. It is an extraordinary claim that (whatever the starting number) the experimenter's choice is constrained, and that a photon will always be "aware" of the detector settings awaiting it and its entangled partner.

 

[gentzen]

Maybe, but if locality is not their motivation, then why are they not satisfied with the Bohmian model?

Hossenfelder told me that one of her motivations is Lorentz covariance and that she doesn't like Bohmian model because it's not Lorentz covariant.

This was indeed the "official" reason Hossenfelder and Palmer gave in Rethinking Superdeterminism:

Pilot-wave theories do, in some sense, solve the measurement problem deterministically. However, pilot-wave formulations of quantum mechanics are based on an explicitly nonlocal ontology, and this nonlocality makes it difficult to reconcile such theories with special relativity and, with that, quantum field theory.

But Bohmian model is not Lorentz covariant precisely because it is not local, I'm not sure whether she is aware of that or not.

That is a tricky question for me, on many different levels. Your "... precisely because ..." might be true, but I cannot judge this myself. And I can judge even less how true or false this is for Hossenfelder or Palmer (or how aware they are of that).
Here is "my argument" why they are probably not aware of that: If they were aware of it, and if they believed that superdeterminism really helped in reconciling determinism with special relativity, maybe they should try to "add" superderminism to pilot-wave theories, and see whether it helps. I guess this would mean to apply the quantum equilibrium hypothesis (and all other relevant probability distributions) not to the initial state at the beginning of the universe, but instead to the state when the "first" measurement happens. To me, this feels like going from a nonlocal model to a super-nonlocal model, but maybe it helps nevertheless.

Another Hossenfelder's motivation, which makes more sense, is that she wants to make new measurable predictions, not just to reproduce the old ones, which makes Bohmian model uninteresting.

Indeed, that ability of the Bohmian model to exactly reproduce the measurable predictions of QM makes it less attractive, because their goal is rather to have QM emerge as "the linear probabilistic description of an underlying nonlinear deterministic system":

But this linearity says nothing whatsoever about whether the dynamics of the underlying system from which the probability density derives is also linear. Hence, chaotic dynamical systems, despite their nonlinear dynamics, obey the same linear equation for probability density. To us, this close formal similarity between the two equations strongly suggests that quantum physics, too, is only the linear probabilistic description of an underlying nonlinear deterministic system.

I also tried to get a general feel for Hossenfelder's motivations for superdeterminism and foundations more general. I got the impression that her priorities are "new predictions" that "can be tested", then compatibility with "special relativity", "second quantization", and "quantum field theory". And she has sympathies for attempts to "explain quantum phenomena as emergent".

http://backreaction.blogspot.com/2013/10/shut-up-and-let-me-think.html

Most of the feedback I got was people telling me they don’t believe in superdeterminism, wanting to know why I believe in it, not that I’m sure I do. Discussions turned towards final causes and theology. I’m a phenomenologist, I heard myself saying, I couldn’t care less what other people believe, I want to know how it can be tested.

As somebody who primarily works in quantum gravity, I admit that I’m jealous of the quantum foundations people. Because they got data. It is plainly amazing for me to see just how much technological progress during the last decade has contributed to our improved understanding of quantum systems. ... When I was a student, none of that was possible. This enables us to test quantum theory now much more precisely and in more circumstances than ever before.

I do have my issues with much of what I’ve seen in quantum foundations. To begin with, most of it seems to be focused on non-relativistic quantum mechanics. That’s like trying to improve the traffic in NYC by breeding better horses. If you can’t make it Lorentz-invariant and second quantized I don’t know why I should think about it.

http://backreaction.blogspot.com/2014/02/a-drop-makes-waves-just-like-quantum.html

...using this theory to explain quantum phenomena as emergent from an underlying classical reality. I can imagine this line of research to become very fruitful also for the area of emergent gravity. ...

While I think this is interesting fluid dynamics and pretty videos, I remain skeptic of the idea that this classical system can reproduce all achievements of quantum mechanics. To begin with it gives me to think that the Lorentz-symmetry is only approximate, and I don’t see what this approach might have to say about entanglement, which for me is the hallmark of quantum theory.

http://backreaction.blogspot.com/2020/10/david-bohms-pilot-wave-interpretation.html

The problem is now that since Bohmian mechanics is not local, it has turned out to be very difficult to make a quantum field theory out of it. Some have made attempts, but currently there is simply no Pilot Wave alternative for the Standard Model of Particle Physics. And for many physicists, me included, this is a game stopper. It means the Bohmian approach cannot reproduce the achievements of the Copenhagen Interpretation.

Bohm himself, interestingly enough, seems to have changed his attitude towards his own theory. He originally thought it would in some cases give predictions different from quantum mechanics. I only learned this recently from a Biography of Bohm written by David Peat. Peat writes

“Bohm told Einstein… his only hope was that conventional quantum theory would not apply to very rapid processes. Experiments done in a rapid succession would, he hoped, show divergences from the conventional theory and give clues as to what lies at a deeper level.”

However, Bohm had pretty much the whole community against him. After a particularly hefty criticism by Heisenberg, Bohm changed course and claimed that his theory made the same predictions as quantum mechanics. But it did not help. After this, they just complained that the theory did not make new predictions. And in the end, they just ignored him.

 

[Fra]

http://backreaction.blogspot.com/2013/10/shut-up-and-let-me-think.html
"I do have my issues with much of what I’ve seen in quantum foundations. To begin with, most of it seems to be focused on non-relativistic quantum mechanics. That’s like trying to improve the traffic in NYC by breeding better horses. If you can’t make it Lorentz-invariant and second quantized I don’t know why I should think about it. "

I find this line to be revealing of the logic and order of inferences Hossenfelder uses.

One can ponder what comes first, observer equivalence or observers? It seems common among those that take a non-physical gauge approach to "observers", to jump right to the observer equivalence, and thus the lack of this is pathological. This is because one usually sees this symmetry as a constraint, that does not correspong to a physical process, but is just a consistency constraint on our theories.

I do not share this view however. I do not think explicit covariance is a necessary prerequisite for reworking QM, as it can be emergent. For me lorentz covariance may well relate to the physics of emergent spacetime, and I don't think spacetime needs to be fully emerged to reconstruct QM. IT depends on the perspective.

/Fredrik