'Toy' universe complying with Bell experiments

[IttyBittyBit]

After reading a bit about Bell's theorem and various hidden variable theories, I thought a little about the detection loophole, and how it gets around Bell's theorem while still allowing a pretty much 'local' Universe. The main argument against this, as I understand it (correct me if I'm wrong) is that it requires some sort of conspiracy and is unfalsifiable.

It occurred to me that it should be possible to 'test' this, in a way, by constructing a simple toy Universe that is totally deterministic yet non-conspiratory but still complies with any Bell test experiment (Stern-Gerlach, for example, or photon polarization).

If it turns out that such a Universe is impossible to construct, then locality would be unquestionably refuted. If it is not impossible, then it still remains open as a possible explanation of reality.

Has anyone ever attempted the construction of a model of such a toy Universe?

 

[Quantumental]

I have absolutely no idea what you are trying to say in this post, could you rephrase it?

 

[IttyBittyBit]

Tell me what parts of the question you find confusing and I'll do my best to elaborate.

 

[ZapperZ]

Don't you think that your toy model has no...MODEL? It has nothing to test. You have presented nothing that can be quantitatively tested. This is not a model.

Zz.

 

[IttyBittyBit]

I'm not presenting a model.

I'm simply asking if someone has attempted to construct a toy Universe that is deterministic, local, and yet appears to produce 'nonlocal' effects like those that are seen in the Bell experiments. One's knee-jerk reaction might be 'but this is impossible!' Actually it's not. As DrChinese pointed out in another thread, one way is to posit the existence of some 'grand conspiracy' that always makes the results of the experiments match up with what is known from the Bell experiments. I'm asking if someone has constructed a toy Universe where this conspiracy either does not exist or can be reduced to the simple rules of the model (just like the 'conspiracy' of the second law of thermodynamics, for example, can be fundamentally attributed to the laws of statistics and probability).

 

[ZapperZ]

I'm not presenting a model.

I'm simply asking if someone has attempted to construct a toy Universe that is deterministic, local, and yet appears to produce 'nonlocal' effects like those that are seen in the Bell experiments. One's knee-jerk reaction might be 'but this is impossible!' Actually it's not. As DrChinese pointed out in another thread, one way is to posit the existence of some 'grand conspiracy' that always makes the results of the experiments match up with what is known from the Bell experiments. I'm asking if someone has constructed a toy Universe where this conspiracy either does not exist or can be reduced to the simple rules of the model (just like the 'conspiracy' of the second law of thermodynamics, for example, can be fundamentally attributed to the laws of statistics and probability).

Note that you stated this:

It occurred to me that it should be possible to 'test' this, in a way, by constructing a simple toy Universe that is totally deterministic yet non-conspiratory but still complies with any Bell test experiment (Stern-Gerlach, for example, or photon polarization).

Unless you are dealing with some philosophical arguments, what you have said means nothing when it doesn't have any underlying mathematical description. When tHooft argues that QM is deterministic, he showed mathematical formulation on why that is so.

I'm not asking you to produce a model. I'm asking for you to show the mathematical criteria that this model must have or satisfy. Without that, this is philosophy, not physics.

Zz.

 

[martinbn]

I agree that saying "can someone make a model such that... " or "can it be proven that.." does not qualify as an idea that can be used to test anything.

On the other hand if the (hypothetical, since you haven't presented one) toy universe is deterministic, how can it be non-conspiratory? The initial state will determine the choices of angles for measurement and the outcomes, no?

 

[robinpike]

I'm not presenting a model.

I'm simply asking if someone has attempted to construct a toy Universe that is deterministic, local, and yet appears to produce 'nonlocal' effects like those that are seen in the Bell experiments. One's knee-jerk reaction might be 'but this is impossible!' Actually it's not. As DrChinese pointed out in another thread, one way is to posit the existence of some 'grand conspiracy' that always makes the results of the experiments match up with what is known from the Bell experiments. I'm asking if someone has constructed a toy Universe where this conspiracy either does not exist or can be reduced to the simple rules of the model (just like the 'conspiracy' of the second law of thermodynamics, for example, can be fundamentally attributed to the laws of statistics and probability).

Hi IttyBittyBit,

For what its worth... I have attempted to construct a deterministic 'Toy' Universe which does not contain quantum mechanical principles. It offers an alternative explanation for such experiments as the two slit experiment; the amount of light reflected from a glass surface being dependent on the thickness of glass; etc without invoking quantum mechanics. Although these experiments aren't specifically Bell experiments, I guess they are related in that they are currently only explained using quantum mechanics.

 

[DrChinese]

Has anyone ever attempted the construction of a model of such a toy Universe?

There have been many many many such attempts, and some are located at arxiv.org. Check out the following link, these are papers with the word "toy" in the title.

http://arxiv.org/find/all/1/ti:+toy/0/1/0/all/0/1

These all feature specific properties which attempt to "bypass" Bell by locating some potential (hidden) assumption and manipulating that. As ZapperZ correctly points out, you end up quickly running afoul of one of several traps: a) you don't really provide a model which reproduces the general predictions of QM; b) it does not actually make any predictions different than QM; and/or c) the differences really amount to definitional or semantic interpretation and there is no real change.

The general point being that Bell provides a strict set of guidelines, and these are no simple restrictions. So to speculate that you could arrive at such is tantamount to asking to be awarded a 100% on test you are sure you could pass, but didn't actually take. Believe me, such models are not really welcome here anyway as this is not a spot for original research to be debated. The quantum physics forum is intended for discussion of mainstream physics.

 

[IttyBittyBit]

DrChinese: Thank you!

Are you sure that's the right link, though? Most of those papers seem to have little, if anything, to do with Bell.

As ZapperZ correctly points out, you end up quickly running afoul of one of several traps: a) you don't really provide a model which reproduces the general predictions of QM; b) it does not actually make any predictions different than QM; and/or c) the differences really amount to definitional or semantic interpretation and there is no real change.

Yes I've come to realize this myself; it is very hard to produce an exact definition for 'conspiracy'; I wasn't sure if this was due to my ignorance or it's just an ill-defined concept in general.

Believe me, such models are not really welcome here anyway as this is not a spot for original research to be debated. The quantum physics forum is intended for discussion of mainstream physics.

I don't see this rule mentioned anywhere in the forum guidelines.

 

[micromass]

I don't see this rule mentioned anywhere in the forum guidelines.

You haven't looked for hard, I think (bolding mine):

Generally, in the forums we do not allow the following:

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Generally, discussion topics should be traceable to standard textbooks or to peer-reviewed scientific literature. Usually, we accept references from journals that are listed here:

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Use the search feature to search for journals by words in their titles. If you have problems with the search feature, you can view the entire list here:

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References that appear only on http://www.arxiv.org/ (which is not peer-reviewed) are subject to review by the Mentors. We recognize that in some fields this is the accepted means of professional communication, but in other fields we prefer to wait until formal publication elsewhere.

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[audioloop]

After reading a bit about 's theorem and various hidden variable theories, I thought a little about the detection , and how it gets around Bell's theorem while still allowing a pretty much 'local' . The main argument against this, as I understand it (correct me if I'm wrong) is that it requires some sort of conspiracy and is unfalsifiable.

Has anyone ever attempted the construction of a model of such a toy Universe?

gerard` t hooft.

 

[DrChinese]

Are you sure that's the right link, though? Most of those papers seem to have little, if anything, to do with Bell.

...

I don't see this rule mentioned anywhere in the forum guidelines.

I was trying to demonstrate that you can search on those yourself. I might suggest the keywords: bell entanglement or epr, If you look deeper, you will discover that almost all such are unpublished. And again, this is really the wrong place to come to because, by definition, toy theories are not generally accepted physics. So I was trying to point a direction for your further study.

As to the forum guidelines, micromass answered that already. While it may seem at first glance that we are not interested in discussing, that is not really so. But you will need to do some preparation of your questions, and you will need to respect the boundaries implied by the guidelines. Remember, in this regard the burden will be on you to keep it relevant.

For example: Gerard 't Hooft (as pointed out by audioloop) has published work on so-called conspiracy theories, usually labelled as "superdeterminism". His work on that is generally given the benefit of the doubt for inclusion here because he is a Nobel laureate. But you will find that he is given no benefit when it comes to discussing the actual merits. That is because many scientists, myself included, think that superdeterminism is not science but more metaphysics (and I am being kind - sorry Gerard) or at best, philosophy. There are already threads on the subject, if you are interested in learning more you can use the PF search to locate.

 

[Quantumental]

For example: Gerard 't Hooft (as pointed out by audioloop) has published work on so-called conspiracy theories, usually labelled as "superdeterminism". His work on that is generally given the benefit of the doubt for inclusion here because he is a Nobel laureate. But you will find that he is given no benefit when it comes to discussing the actual merits. That is because many scientists, myself included, think that superdeterminism is not science but more metaphysics (and I am being kind - sorry Gerard) or at best, philosophy. There are already threads on the subject, if you are interested in learning more you can use the PF search to locate.

Brief comment: of course 't Hoofts status in the history of physics is important, but his work has not received a lot of attention. The little attention his work has got has been due to him putting out several papers on it.

 

[IttyBittyBit]

DrChinese, again thanks for the wonderful explanation.

I came here looking for a rigorous mathematical model of a 'superdeterministic' Universe. However, if I understood the discussion correctly, such a model either cannot be made or winds up being mathematically identical to the 'mainstream' interpretation, with the only differences being matters of interpretation. Correct me if I'm wrong here.

 

[DrChinese]

DrChinese, again thanks for the wonderful explanation.

I came here looking for a rigorous mathematical model of a 'superdeterministic' Universe. However, if I understood the discussion correctly, such a model either cannot be made or winds up being mathematically identical to the 'mainstream' interpretation, with the only differences being matters of interpretation. Correct me if I'm wrong here.

I think that is fair to say. You can't really say "I have a model like QM but that is superdeterministic" without telling us HOW it accomplishes this feat.

For example: if everything is a conspiracy, and Bell test results reflect that locally, then there must be some kind of DNA in every particle that tells it precisely WHEN to deviate from the normal laws and comply with Bell (i.e. it violates a Bell Inequality only during Bell tests). Where is that DNA? And it must have a complete history of the entire universe, past and present, because it is the starting conditions that predetermined everything. Whoa, that's quite a bit of info to pack into the DNA of every single particle. You end up adding rule after rule and it never ends. Which is why we never see any specifics.

Further, why limit superdeterminism to Bell? Why not say that the gravitational constant is H but due to superdeterminism it appears to be G when measured?

And finally, at the end of the day, we end up with sQM anyway as our map for making predictions.

 

[mfb]

There is an interpretation of quantum mechanics which is both deterministic and local and consistent with experiments: Many worlds.
Your toy universe is possible, assuming "totally deterministic" refers to the state of the universe.

 

[DrChinese]

There is an interpretation of quantum mechanics which is both deterministic and local and consistent with experiments: Many worlds.
Your toy universe is possible, assuming "totally deterministic" refers to the state of the universe.

Might be stretching the word "deterministic". Each universe does not lead to a single inevitable new universe in any meaningful sense, since every outcome is realized. In other words, if you knew the state of the universe (or some system), you could still never predict with certainty any future state after an observation. It would be a random outcome, depending on the branch you fell into.

 

[mfb]

If you know the state of the universe, you can predict the future state of the universe - that is "deterministic".

you could still never predict with certainty any future state after an observation

Of course you can. You can predict "there will be some 'me' which sees X, they have a measure of p. And there will be some 'me' which see not X, they have a measure of q".
The future branches of "you" will see different things, so what?

depending on the branch you fell into.

In all branches, of course.

 

[DrChinese]

If you know the state of the universe, you can predict the future state of the universe - that is "deterministic".

...

Of course you can. You can predict "there will be some 'me' which sees X, they have a measure of p. And there will be some 'me' which see not X, they have a measure of q".
The future branches of "you" will see different things, so what?

So every measurement answer "proves" your definition correct. I have a term* for that idea, and it is much the same as my opinion of superdeterminism. Note that my opinion is not about MWI itself, it is simply an opinion about your description of it. I have heard it said that MWI is local and realistic (which I would dispute), but I don't believe most physicists would share your viewpoint that MWI is also deterministic.

And, to be clear: You cannot, in principle, predict the outcome of a quantum measurement on any prepared system unless you are simply measuring an observable, the value of which you already knew. Otherwise, you would violate the Uncertainty Principle.

*However, it is not complimentary.

 

[audioloop]

If you know the state of the universe, you can predict the future state of the universe - that is "deterministic".


Of course you can. You can predict "there will be some 'me' which sees X, they have a measure of p. And there will be some 'me' which see not X, they have a measure of q".
The future branches of "you" will see different things, so what?


In all branches, of course.

Determinism does not equate with Predictability.
there are deterministic processes that are not predictable.

 

[Jazzdude]

And, to be clear: You cannot, in principle, predict the outcome of a quantum measurement on any prepared system unless you are simply measuring an observable, the value of which you already knew. Otherwise, you would violate the Uncertainty Principle.

Can you point to where you believe the uncertainty principle comes in for predicting measurement outcomes?

 

[DrChinese]

Can you point to where you believe the uncertainty principle comes in for predicting measurement outcomes?

If you know a quantum system's value of p, it is not possible it is not possible to predict it's q - even in principle. That is the HUP.

 

[Jazzdude]

If you know a quantum system's value of p, it is not possible it is not possible to predict it's q - even in principle. That is the HUP.

No, the uncertainty principle is a constraint on the quantum phase space that comes from the canonical commutation, the Weyl-Heisenberg group and the emergent non-commutative geometry. It has only remotely to do with measurement and in my eyes does not affect predictability of measurement outcomes at all.

 

[mfb]

So every measurement answer "proves" your definition correct.

No, but you can do reasonable physics with MWI. See this description, for example.

but I don't believe most physicists would share your viewpoint that MWI is also deterministic.

I do not know of any survey, but a quick google search (here with indeterministic) shows that MWI is usually considered as deterministic. Or, more precise, that the word "deterministic" is interpreted in a way that MWI satisfies it.

If you think MWI is not deterministic: Is there any interpretation you would call deterministic?
De-Broglie-Bohm might look "more deterministic", but you cannot measure the precise state of the particles in this theory, so (some) future measurements are random according to everything you can know today.


@audioloop: I don't think this is relevant here. The prediction is different from a classical prediction ("that happens"), but it can be exact.

 

[DrChinese]

1. No, but you can do reasonable physics with MWI. See this description, for example.

2. I do not know of any survey, but a quick google search (here with indeterministic) shows that MWI is usually considered as deterministic. Or, more precise, that the word "deterministic" is interpreted in a way that MWI satisfies it.

1. As mentioned, I am not making any statement about or against the physics of MWI. It is a bit funky to send us to a reference of your own words, by the way.

2. I really don't think it makes sense to (re)define a word like "deterministic" so you can claim to be right. If you specify a state of a system, you cannot use MWI - in principle - to predict outcomes of measurements with certainty. The outcome is always one out of MANY branches, hence the name MANY WORLDS. So I don't even know why you would try to connect that idea to MWI in the first place.

 

[mfb]

It is a bit funky to send us to a reference of your own words, by the way.

I did not want to write it again, and the post had exactly what I would have written if that post would not exist.

2. I really don't think it makes sense to (re)define a word like "deterministic" so you can claim to be right.

Wait, who is redefining something? The google results indicate that "deterministic" is often used in some specific way. And with that specific way (but not restricted to it), MWI is deterministic. No redefinition happening.
Anyway, that is just a word game, and I don't like those.

If you specify a state of a system, you cannot use MWI - in principle - to predict outcomes of measurements with certainty. The outcome is always one out of MANY branches, hence the name MANY WORLDS.

The outcome is always multiple worlds, and not just one (otherwise you have collapses, or de-Broglie-Bohm, or similar things).