How can we test the holographic principle and nonlocality in quantum mechanics?

[Careful]

There is no issue of non-locality, neither is there a problem for realism. It is perfectly possible to construct locally causal, realist theories in which nonlocal correlations between ``particle-events'' can be measured. So all Bell's theorem shows it that if you take particles to be fundamental degrees of freedom *and* insist upon local causality then QM is outside this class. It is of course a very different matter to construct such theory which reproduces QM, but yes an ideal Bell test does not even refute local realism (actually it seems the latter class contains QM). If you drop the requirement of local, then I guess S. Adler has already given evidence of this. If you want to have a reference for this opinion, check out the papers of 't Hooft.

Careful

To clarify this : the particle assumption is actually hidden in the Kolmogorov assumption (factorizing of probability). The intuitive justification for this assumption is that particles with opposite spin traveling in opposite directions shall always exist and more or less follow the classical path at speed less than the speed of light, making interaction impossible if the detector settings cannot be communicated (again limited by the speed of light). However the latter assumptions do not hold in ordinary QFT (particles can be annihilated while other particles reappear at spacelike separated distances), where particles are local excitations of the field. By seeing particles as a statistical (coarse grained) property of the field, it is possible to mimic particle creation/annihilation in a deterministic, LOCAL theory ( --> violation of Kolmogorov assumption). This is, I think, a part of the possibility expressed by 't Hooft.

Here is a useful reference : http://arxiv.org/PS_cache/cond-mat/pdf/0403/0403692.pdf by Peter Morgan of Yale. This is about stochastic models, in which 't Hoofts determinism fits in nicely : basically, it is impossible to write down a deterministic equation for the ``particle'' so that the particle dynamics is effectively stochastic. It is cute to notice that the Bell limit for stochastic modes exceeds the one for QM.

Careful

 

[RandallB]

To clarify this ... (particles can be annihilated while other particles reappear at spacelike separated distances), where particles are local excitations of the field.
By seeing particles as a statistical (coarse grained) property of the field, it is possible to mimic particle creation/annihilation in a deterministic, LOCAL theory ...

BUT your "mimic" can not be completed without using the annihilation to creation steps with the "statistical (coarse grained) property", AKA particles, reappearing as you have described "at spacelike separated distances"!

That means they have changed location FTL - how much more NON-LOCAL can you get.

Your own explanation and clarification falsify this idea’s (not even a theory) initial premise that “There is no issue of non-locality”. Clearly your solution is non-local.

 

[Careful]

BUT your "mimic" can not be completed without using the annihilation to creation steps with the "statistical (coarse grained) property", AKA particles, reappearing as you have described "at spacelike separated distances"!

That means they have changed location FTL - how much more NON-LOCAL can you get.

Your own explanation and clarification falsify this idea’s (not even a theory) initial premise that “There is no issue of non-locality”. Clearly your solution is non-local.

No, I have not changed location FTL : there is even no deterministic law for the change of particle position (even position is a coarse grained concept) - it could even be that a particle dissapears and two of them appear at the same time at spacelike separated distances. The proposal (of 't Hooft and many others) is entirely local, you might want to think about that - anyway have to go now.

Careful

 

[Farsight]

That means they have changed location FTL - how much more NON-LOCAL can you get.

By not starting off with particles in the first place? By considering that the entities we are dealing with are simply not point particles? How can I put it? Sorry to be cynical, but how about this:

The quantum of water in a fireman's hose is the gallon. But a gallon isn't all in one place. Which means it's in two places at once. Therefore Parallel Universes, Many Worlds, QED.

 

[RandallB]

No, I have not changed location FTL : ...
a particle dissapears and two of them appear at the same time at spacelike separated distances.

Once again, self defeating and contradicting statements – this time inside a single sentence.

Non-Locality does not go away by waving your hands over the useful simultaneous forming of particles at space-like separations (i.e. information being shared FTL) and just claiming: “This is Local, not Non-Local, it just has no local explanation of how it correlates perfectly with the Non-Local assumptions of theories like QM (probabilities) and BM (guide wave) etc.”

So NO-Dice, I don’t accept this as a “Local” solution, invalidating Non-Local Theories!
I’ll look at QM and BM as legit competing non-local theories, even though I’d prefer a local one that works. But this thing whatever you call it; is ether an ill formed idea, or gross misinterpretation of a 't Hooft Non-Local concept.

 

[Careful]

By not starting off with particles in the first place? By considering that the entities we are dealing with are simply not point particles? How can I put it? Sorry to be cynical, but how about this:

Dear Farshight,

If you don't understand what I am saying, then you could politely ask me or you could at least try to read the papers I mentioned above. A certain class of toy models in which you can achieve this are cellular automatons.

Careful

 

[Careful]

Dear RandallB,

The same comment applies to you.

**
Once again, self defeating and contradicting statements – this time inside a single sentence. Non-Locality does not go away by waving your hands over the useful simultaneous forming of particles at space-like separations (i.e. information being shared FTL) and just claiming: “This is Local, not Non-Local, it just has no local explanation of how it correlates perfectly with the Non-Local assumptions of theories like QM (probabilities) and BM (guide wave) etc.” **

I do not contradict myself in any way :grumpy: and if you find any self defeating sentences of mine you are welcome to report them to me.
If a particle dissapears somewhere it simply does not exist anymore (period) - so you clearly did not understand this sentence.

BM has the wrong starting point, it starts from non relativistic QM and not QFT. What 't Hooft basically says is that the dynamics at the Planck scale is deterministic, local and chaotic; particles are hughe collections of these Planckian vibrations. The idea is that if you look at the effective dynamics at the scale of the particles, then you would have (to an excellent approximation) a stochastic theory (in which you can treat the particles like points). Stochastic theories can violate the Bell inequalties (actually the normal limit is 2, QM = 2 sqrt(2) and stochastic is 4).

references are : quant-ph/0212095 and http://www.phys.uu.nl/~thooft/gthpub/DiceWorld.pdf

And who said that this option INVALIDATES non local theories (?), you are imagining things I have never said and cannot read the things I say. I said there is no ISSUE of local realist versus non local (realist or not) in the context of Bell experiments, at least not on the simplistic level you are talking on - it might be on a much more sophisticated level, but that is unknown. Anyone who can read the latter sentence knows that it means : measurement of an EPR state is not the way to refute local realist theories.

On the other hand Zapperz raised valid comments on another thread : interpretations of QM, what is nature really like ?

Careful

 

[RandallB]

The same comment applies to you.

You need to be more specific.
Which comment applied to what claim of mine?
If you can be detailed here I’ll try to clarify what ever it is I claimed that you don’t understand.

And who said that this option INVALIDATES non local theories (?), you are imagining things I have never said and cannot read the things I say. I said there is no ISSUE of l...

In post 106 you claimed “There is no issue of non-locality, neither is there a problem for realism.” QM claims and depends on Non-Local being a fact, managed by HUP. If as you say there is no issue of non-locality than that is claiming that QM is wrong.

Did you miss the point that Farsight was supporting your position and trying to resolve my complaint. His “Quantum Gallon” can be as large as he likes and contain the action of a particle or a pair of entangled particles. I’m satisfied that he is correct that is a fair way and a fair analogy of what your describing that does provide a solution to Bell.
My problem is I cannot accept that as a “Local” and “Real” solution until the action inside that “Quantum Gallon” (Farsight likes using descriptive names for a particle or ‘entity’) is clearly defined in descriptive local terms. - Random chaotic stochastic assumptions taken to an “to an excellent approximation”, so that ‘a particle disappears somewhere’ while at the same time at space-like separation something can appear retaining correlating information from it, is just not good enough to be defined as LOCAL.

Mind you proving the world is Local is my own goal and belief, but I won’t claim or accept it without a complete and convincing LOCAL explanation.
Non-Locality as needed by QM and others is an acceptable real issue, not a non-issue.
Not until you, Farsight, myself or someone can do that, will we be proving QM wrong.

 

[Farsight]

Dear Farshight,

If you don't understand what I am saying, then you could politely ask me or you could at least try to read the papers I mentioned above. A certain class of toy models in which you can achieve this are cellular automatons.

Careful

Farshight?

Please can you repost a link to one selected paper along with a very brief restatement of what you're saying.

 

[Careful]

**
If you can be detailed here I’ll try to clarify what ever it is I claimed that you don’t understand.In post 106 you claimed “There is no issue of non-locality, neither is there a problem for realism.” QM claims and depends on Non-Local being a fact, managed by HUP. If as you say there is no issue of non-locality than that is claiming that QM is wrong. **

I don't know your level in physics (my answer would depend on that, no offense ), but fine. First of all, it are the Copenhagen, Bohm-de Broglie and spontanious collapse model (let me restrict to the realist interpretations) FORMULATIONS which are non-local; this does not imply that the predictions of QM necessarily emerge from a non-local theory. As to my physical intuition, I cannot imagine a theory which is neither realist, neither local and I have met nobody who can make sense of that. It is my deep conviction that ultimately the laws in physics for the CORRECT fundamental degrees of freedom are local, therefore I think the current FORMULATION of QM is incomplete : this is far from saying that QM is wrong.

You need to take as starting point quantum field theory where particles get created and annihalated, these are all local processes: to mimic this you can can start from a theory containing more fundamental degrees of freedom. I am currently not going to give more details of the specific automaton model I have in mind; but the references I provided should give enough hints.


**
Did you miss the point that Farsight was supporting your position and trying to resolve my complaint. His “Quantum Gallon” can be as large as he likes and contain the action of a particle or a pair of entangled particles. I’m satisfied that he is correct that is a fair way and a fair analogy of what your describing that does provide a solution to Bell. **

He was not helping me, he thinks in terms of parallel universes and all that nonsense - this is not what I was talking about at all.

**
My problem is I cannot accept that as a “Local” and “Real” solution until the action inside that “Quantum Gallon” (Farsight likes using descriptive names for a particle or ‘entity’) is clearly defined in descriptive local terms. **

The whole point is that the effective action for the particle is not (necessarily) local(ly stochastic) - while the dynamics for the true degrees of freedom is.

** Random chaotic stochastic assumptions taken to an “to an excellent approximation”, so that ‘a particle disappears somewhere’ while at the same time at space-like separation something can appear retaining correlating information from it, is just not good enough to be defined as LOCAL. **

But it is (!), you still do not understand what I am talking about. As a *simple* example, imagine yourself a particle (momentum p, spin s) which moves to the right at t = 0. At the same time, a particle - anti particle pair can be created at x = L > 0; the particle having momentum close to p and also spin s. The first particle and the anti-particle will meet approximately at L/2, they disappear and you are left with a perfectly correlated particle at x = 3L/2 !

The thing I try to learn you is that local realism is not necessarily in conflict with QM if you try to understand the correct theory, which is QFT. Really, read the papers of 't Hooft... I think I said in one of my first posts here that QM is an emergency solution; it is of course much easier to construct a nonlocal theory accounting for appearantly non local phenomena when you add a rule of thumb without further explanation (the famous reduction). However, one must REMEMBER one did not have a better idea at the time instead of looking for science fiction explanations to promote the ignorance as newly acquired deep understanding - although it is deep in the sense that it beautifully fits with experiment.



Careful

 

[RandallB]

Careful

As I read your last paragraph your saying hooft claims that his interpretation of QFT indicates that local realism might not necessarily be in conflict with QM.
I have no problem with that -- I disagree with the idea, but it is a good bit short of declaring that "There is no issue of non-locality" as being a settled issue.
If it was successful in settling the issue; I'd expect to see a GUT and likely a TOE come from the theory rather directly.

I understand the anti-particle idea being used here.
And I disagree about Farsight - his is not MWI and a fair view that can use what you are saying here in trying to resolve the GR vs. QM issue. I actually think his Quantum Gallon analogy is a rather good one -- BUT still: the instant jump from L/2 to 3L/2 is FTL; & with no reason for the pair at space-like separated L to start off as a match to the particle at 0, this is filled with non-local issues.

As a local realist myself, I believe a local theory will ruin QM and non-locals. Maybe the math of QFT may well remain as a description of something else not currently understood.

My standard for confirming "LOCAL" is very high - I see it as the only way to avoid and move on from crackpot local ideas and those that are in realty non-local. This one, for me at least, falls into the latter.
I don't expect any Mentors or Advisors to step in and say the scientific community accepts this as settled; So let's leave it that it doesn't work for me.

 

[Careful]

**
As I read your last paragraph your saying hooft claims that his interpretation of QFT indicates that local realism might not necessarily be in conflict with QM.
I have no problem with that -- I disagree with the idea, but it is a good bit short of declaring that "There is no issue of non-locality" as being a settled issue. **

No, it is not : there exist examples of local, classical theories which reproduce EPR correlations; however these can fairly be dismissed as being conspirational. The point about locally stochastic theories is that they can violate without problem the various forms of Bell's inequalities and do so in a *natural* way. So, there is in no obvious way an issue of non-locality in the sense that BOTH viewpoints appear to be possible so far. But I can hardly think of a *fundamental* stochastic dynamics for the universe too.

**If it was successful in settling the issue; I'd expect to see a GUT and likely a TOE come from the theory rather directly. **

Right, that is it's aim - although it is not that easy (computationally).

**
-- BUT still: the instant jump from L/2 to 3L/2 is FTL; & with no reason for the pair at space-like separated L to start off as a match to the particle at 0, this is filled with non-local issues **

No, it is not - it is just about the statistics of the vacuum (L is to be interpreted statistically of course). As far as Farsight goes, I don't know him, neither his opinions, therefore one should avoid metaphors.

**
As a local realist myself, I believe a local theory will ruin QM and non-locals. Maybe the math of QFT may well remain as a description of something else not currently understood. **

So, you are betting all your money on a perfect Bell test never being done and keeping particles as fundamental degrees of freedom ? Or are you in the locally stochastic camp ? Moreover, I disagree with you when you say that a local theory will ruin QM : as I see it, IF QM is RIGHT predictionwise, then any such local theory is much more complicated and the formalism of QM will certainly remain as a very useful tool.

I don't see any point in discussing about locality versus non-locality as is done here: local realism is not ruled out in any obvious way, so it is up to local realists to offer an alternative theory; all the rest is blabla.

**
My standard for confirming "LOCAL" is very high - I see it as the only way to avoid and move on from crackpot local ideas and those that are in realty non-local. This one, for me at least, falls into the latter. **

It is clearly local, except that you refuse to see particles as emergent properties. So, I assume you have no desire to reproduce particle creation/annihilation ?

Careful

 

[RandallB]

it is just about the statistics of the vacuum (L is to be interpreted statistically of course).

Sure --- very much as a HUP non-local uncertainty.
And I do trust your explanation of this one to know it is not one I need to dive into deeply - so thanks.

So, you are betting all your money on ...

No, - I'm am betting.
But on my terms and on my expectations, not yours or your assumptions.
Any good solution will be simpler and more fundamentally clear than what we see today not more complex.

 

[Careful]

**Sure --- very much as a HUP non-local uncertainty.
And I do trust your explanation of this one to know it is not one I need to dive into deeply - so thanks. **

Huh ?? It has nothing to do with HUP (!), it is merely classical statistics.

**
But on my terms and on my expectations, not yours or your assumptions.
Any good solution will be simpler and more fundamentally clear than what we see today not more complex.**

You do not say anything here, neither do you answer any of my questions and neither do you tell us how you are going to try to avoid clashes with Bell inequalities. So, I ask you again, what is your point of discussing all this ??

Careful

 

[Farsight]

Careful:

I'm not somebody who thinks MWI is the correct picture of reality. I'm somebody who thinks that there's confusion between a quantum and a particle, and this may be the root of QM interpretation problems. For example:

You need to take as starting point quantum field theory where particles get created and annihilated

 

[Careful]

Careful:

I'm not somebody who thinks MWI is the correct picture of reality. I'm somebody who thinks that there's confusion between a quantum and a particle, and this may be the root of QM interpretation problems. For example:

So, what is wrong with that statement ?? Are you denying particle - anti particle pair creation out of the vacuum ? Please SAY something substantial, give us your alternative - your view on nature. How do you think to bypass some quantum mechanisms ? If you are a Bohmian, then you must be aware that there exists no -even remotely- convincing interpretation for QFT. Instead of making cryptic sentences you might better be straightforward, so that we see where the beef is.

Careful

 

[Farsight]

I wish you'd stop being snippy.

Yes, I guess I am denying particle/antiparticle pair creation out of the vacuum. In a way. Bear with me.

You asked what's wrong with this statement:

You need to take as starting point quantum field theory where particles get created and annihilated

What's wrong with it, is the confusion between quanta and particles. It should read:

You need to take as starting point quantum field theory where quanta are created and annihilated

There's a world of difference between the two. If you take particles as your starting point you are forever bogged down with mystery caused by the "quanta are particles" axiom.

I'll try to give an illustration: I view a photon as a traveling warp with a given energy. It has no edge. It has no surface. It has no point location. It's the electromagnetic equivalent of a shout. Seen any "shout" particles recently? And isn't it amazing how a shout manages to be in two places at once?

http://en.wikipedia.org/wiki/Quantum_field_theory

 

[vanesch]

I would like the different antagonists to answer some point for me, because there seem to be strange statements made here.

As far as I know, Bell has nothing to do with particle/no particle or whatever. What Bell discusses, is just a list of OBSERVATIONS without making any assumptions of any underlying mechanism, except the following one: all probabilities are descriptions of ignorance.

A deterministic theory is local if something happening at event A is entirely determined by what is in A's past lightcone. The extention of the notion to a probabilistic theory is: the probability of something happening at event A is entirely determined by what is in A's past lightcone. This is the most sensible extension to stochastic theories from deterministic theories, but it has to be said that this is an extra assumption. Indeed, "locality" doesn't mean anything anymore with IRREDUCIBLE stochastic theories, because "things just happen" and there's no way to avoid conspiracies.

However, if we take it that nature is fundamentally deterministic, and we say that all "probability" is ignorance-based, then both definitions of locality are identical: the probability of something happening at A describes exactly the ignorance of the precise state of nature in A's past lightcone (which, if we would know it, would allow us to find exactly the outcome at A without any uncertainty).

We call such a definition of local: Bell-local.

This means that any apparent CHANGE in the probability at A can only come about, in a Bell-local theory, by a CHANGE of our knowledge of the precise state of A's past lightcone (by, for instance, learning about another measurement result somewhere else).

This means that there is some "total information" T which would uniquely determine the outcome at A, and that the probability of A is nothing else but P(A) = P(T), the probability (ignorance description) of the different T.

If we have some other observations OUTSIDE of A's past light cone, at B, then the correlation P(A,B) = P(A|B) P(B) must be entirely dependent on the information of A's past lightcone in B.

Now, Bell considers an event at A and 3 different kinds of events at B: B1, B2, B3, and considers that there is an overall probability distribution P(A,B1,B2,B3), the reason being that the decision of whether it will be B1, B2 or B3 is made outside of A's past lightcone, and hence can in no way alter the information that will determine A (namely T).
Purely from the existence of this probability distribution, Bell derives the Bell inequalities, which put a condition on P(A|B1), P(A|B2) and P(A|B3), which is violated by the predictions of the quantum formalism.

Note that this only pertains to OBSERVED CORRELATIONS OF MEASUREMENT RESULTS. Nowhere, any assumption is made about any MECHANISM.
The only thing which is done, is the extension of the concept of locality, which only makes strictly sense for deterministic theories, to "apparently stochastical" theories. As such, it coincides with the requirement of locality for underlying deterministic theories where probabilities are just descriptions of ignorance.
In the case of irreducible stochastic theories (for which no definition of locality holds ! "things happen" can be entirely conspirational), it is an extension of the concept of "local".

So I was wondering how anyone could claim that nature is still local, measurements are still objectively happening events with unique outcomes, and perfect Bell tests are in agreement with quantum theory.

That can, IMO, only happen by redefining "local" into something else.
One has then to demonstrate that this redefinition doesn't also allow a Faster Than Light telephone to be "local".
(in the sense that 3 is smaller than 2, for sufficiently large values of 2 )

In the above reasoning, nowhere, is made use of "particles" or "waves" or whatever. Just a consideration of probabilities of outcomes of measurement, as a function of a choice between 3 possible measurements, entirely independent of whatever phenomenon that might generate it.

BTW, I would, for the n-th time, want to underscore that MWI-QM *IS* a local "realist" theory in agreement with Bell, in that it is "realist" (objective description of nature), it is "local" (all dynamics is local)...
but the cop-out is of course that there are no unique measurement results at A and B. Both results happen. And the correlation is only happening upon A and B meeting ; because at this point, the states contain already the information of the choice at B, and hence can "pair up" in the right way to produce the correct correlations.

 

[Careful]

**
Yes, I guess I am denying particle/antiparticle pair creation out of the vacuum. In a way. Bear with me.

I'll try to give an illustration: I view a photon as a traveling warp with a given energy. It has no edge. It has no surface. It has no point location. It's the electromagnetic equivalent of a shout. Seen any "shout" particles recently? And isn't it amazing how a shout manages to be in two places at once? **

So, are you telling that the Schroedinger wave represents some energy density, in blatant conflict with the probability interpratation? In this way you never solve the measurement problem since you would need to explain the sudden collapse to a particle state.

 

[ttn]

As far as I know, Bell has nothing to do with particle/no particle or whatever.

That's true. I stopped following this thread because the sub-debate it degenerated into is 100% off the track.

But...

What Bell discusses, is just a list of OBSERVATIONS without making any assumptions of any underlying mechanism, except the following one: all probabilities are descriptions of ignorance.

That is absolutely false. To say that all probabilities are descriptions of ignorance, is to say that one insists on determinism -- i.e., that one is unwilling to accept the possibility of an irreducibly stochastic theory. This is just simply wrong as a description of Bell's assumptions. Bell does *not* assume determinism, as he stressed over and over again in his later papers (because people kept insisting that his derivation relied on determinism).

A deterministic theory is local if something happening at event A is entirely determined by what is in A's past lightcone. The extention of the notion to a probabilistic theory is: the probability of something happening at event A is entirely determined by what is in A's past lightcone.

That's right, except what you said above implies that you actually misunderstand what you wrote here. To make it more precise, you should say: the probability *that an irreducibly stochastic theory attributes to* something happening at event A is entirely determined by what is in A's past lightcone. The probabilites in "Bell Locality" are *not* epistemic -- they are the fundamental dynamical probabilities that some candidate stochastic theory assigns to things. And what Bell Locality amounts to is the requirement that these probabilities be based on (as, for example, the probabilities in OQM are based on the wave function) stuff/events/beables in the past light cone of the event in question. The probabilities assigned to an event in a Bell Local theory do not depend on stuff outside the past light cone.

This is the most sensible extension to stochastic theories from deterministic theories, but it has to be said that this is an extra assumption.

It's no more or less an assumption than the definition of "local" for deterministic theories. It's just a more general definition of "local".

Indeed, "locality" doesn't mean anything anymore with IRREDUCIBLE stochastic theories, because "things just happen" and there's no way to avoid conspiracies.

That's preposterous. Of course "locality" still means something for irreducibly stochastic theories. Yes, in a sense, "things just happen", but it's not a cosmic free-for-all. Random events still have a *basis* -- e.g., in OQM (which is surely irreducibly stochastic, yes?) the probability for some event is one value if the wave function is such and such, but the probability is some other value if the wave function is instead so and so. The probability for the event *depends on* what the wave function is. That's just an example with a specific theory. The general point is that even in a stochastic theory, the probabilities will always depend on *something* (otherwise, you have no theory) -- and then it makes sense to ask whether the relevant "somethings" are or aren't exclusively in the past light cone.

However, if we take it that nature is fundamentally deterministic, and we say that all "probability" is ignorance-based, then both definitions of locality are identical: the probability of something happening at A describes exactly the ignorance of the precise state of nature in A's past lightcone (which, if we would know it, would allow us to find exactly the outcome at A without any uncertainty).

This represents a failure to understand/appreciate Bell Locality. The mathematical conditions requires a *complete* specification of beables in the past light cone. That's Bell's "lambda". (Completeness is of course defined by whatever particular candidate theory one is assessing.) To say that the probabilities in Bell Locality (which are always conditional on this lambda) are ignorance-based is to say that, really, there is some unknown fact which *determines* outcomes, but which is not contained in lambda (hence we only have probabilities, not determinate predictions). But this is all contradictory. That lambda provides a complete state description is *assumed*. You can't just come back later and say "well maybe really it doesn't, and the probabilites are really ignorance-based rather than fundamental". To say that is not some kind of objection to bell's locality criterion -- it's simply to change midstream what theory one is talking about. And if you're too scatterbrained to keep thinking about the same theory through the whole analysis, don't blame it on bell!

We call such a definition of local: Bell-local.

This means that any apparent CHANGE in the probability at A can only come about, in a Bell-local theory, by a CHANGE of our knowledge of the precise state of A's past lightcone (by, for instance, learning about another measurement result somewhere else).

Huh? That is not at all what Bell Locality says.

Now, Bell considers an event at A and 3 different kinds of events at B: B1, B2, B3, and considers that there is an overall probability distribution P(A,B1,B2,B3), the reason being that the decision of whether it will be B1, B2 or B3 is made outside of A's past lightcone, and hence can in no way alter the information that will determine A (namely T).
Purely from the existence of this probability distribution, Bell derives the Bell inequalities, which put a condition on P(A|B1), P(A|B2) and P(A|B3), which is violated by the predictions of the quantum formalism.

All of this talk about "information" is completely off the track. Bell Locality has nothing to do with information, because the probabilities that condition is about are the fundamental dynamical probabilities assigned to events by a stochastic theory -- and this is something that doesn't in any way at all depend on what information anyone does or doesn't have. A theory just makes the (probabilistic) predictions that it makes. That's it. What anybody knows or doesn't know has nothing to do with it. The question is: are those predictions (the probabilities for various possible happenings at some event) based on beables in the past light cone exclusively, or not? If so, the theory is Bell Local. If not, not.

Note that this only pertains to OBSERVED CORRELATIONS OF MEASUREMENT RESULTS. Nowhere, any assumption is made about any MECHANISM.

You have it just backwards. There *is* (something like) an assumption of a mechanism -- namely, there is an assumption of some particular theory. This comes in because the idea of a "complete state description lambda" is something that only some candidate theory can specify. And as I've said the probabilities in Bell Locality are the probabilites assigned by this candidate theory (based on lambda, etc.). The point is then that Bell's Theorem is *general*: the inequality should be satisfied by *any* theory satisfying the locality criterion. So, in that sense, there is no assumption of a *specific* mechanism (particles or whatever). Technically, the theorem is just this: no local theory (i.e., no candidate "mechanism" which respects relativity's prohibition on superluminal causation) can make predictions in violation of the inequality.

In regard to the first part -- Observed Correlations of Measurement Results -- that is just what the P's in Bell Locality do *not* represent.

The only thing which is done, is the extension of the concept of locality, which only makes strictly sense for deterministic theories, to "apparently stochastical" theories.

Huh? What "apparently"? Bell Locality is a condition that applies to *actually*, irreducibly stochastic theories. You're just wrong if you think there is some illicit tacit determinism assumption here.

As such, it coincides with the requirement of locality for underlying deterministic theories where probabilities are just descriptions of ignorance.

Wrong. You need to go back and re-study Bell's discussions in "Theory of Local Beables" and "La Nouvelle Cuisine."

In the above reasoning, nowhere, is made use of "particles" or "waves" or whatever.

Yes, that's right, and it's why this thread has been so pointless lately. Some particular candidate theory might involve "particles". And it would indeed be subject to the bell inequality, if it is local. But some other theory might instead be in terms of waves or fuzzballs or who knows what, and never mention particles. And... drumroll... it *too* will be subject to the inequality if it is local. This seems to be the point that certain recent posters on this thread don't understand. If Bell's Theorem only applied to particle-based theories (or whatever) nobody would care. It would be totally uninteresting.

BTW, I would, for the n-th time, want to underscore that MWI-QM *IS* a local "realist" theory in agreement with Bell, in that it is "realist" (objective description of nature), it is "local" (all dynamics is local)...

What do you mean "in agreement with Bell"? MWI is indeed "local realist" (in some sense of "realist", though not others) but it does *not* make predictions that violate Bell's Inequalities... if that's what you were trying to imply (that MWI is a counterexample to the claim that Bell proved no local theory can predict violations of the inequalities).

but the cop-out is of course that there are no unique measurement results at A and B. Both results happen.

Right, which is why its predictions -- for what *actually happens* -- do not violate the inequalities. Of course, it also "predicts" that observers are systematically deluded into believing that there were definite measurement results at A and B, and that these delusional/fantasy results violate the inequalities. But since that is just delusional fantasy, and not the real state of things, there's no point talking about it.

BTW, I've just completed a paper on some of these topics, titled "Against 'Realism'" (after Bell's paper "Against 'Measurement'"). Watch for it at an arxiv near you sometime next week (after I have a chance to edit it a bit).

 

[Careful]

**
As far as I know, Bell has nothing to do with particle/no particle or whatever. What Bell discusses, is just a list of OBSERVATIONS without making any assumptions of any underlying mechanism, except the following one: all probabilities are descriptions of ignorance.

A deterministic theory is local if something happening at event A is entirely determined by what is in A's past lightcone. **

Well, This is the case for the local beables of the theory, but not for the changeables. Bell assumes that particles and their properties are beables (spin and particles are ontologically real). 't Hooft drops this condition.

**
The extention of the notion to a probabilistic theory is: the probability of something happening at event A is entirely determined by what is in A's past lightcone. This is the most sensible extension to stochastic theories from deterministic theories, but it has to be said that this is an extra assumption. Indeed, "locality" doesn't mean anything anymore with IRREDUCIBLE stochastic theories, because "things just happen" and there's no way to avoid conspiracies. **

Right, although local stochastic theories are clearly local.

**
However, if we take it that nature is fundamentally deterministic, and we say that all "probability" is ignorance-based, then both definitions of locality are identical: the probability of something happening at A describes exactly the ignorance of the precise state of nature in A's past lightcone (which, if we would know it, would allow us to find exactly the outcome at A without any uncertainty). **

Well, the theory for the beables is local and deterministic (the Planckian oscillations), but not necessarily the effective theory for the changeables (= particles, particle spin and so on). See : hep-th/0104219 for an introduction to the idea.

**
We call such a definition of local: Bell-local.
**

Again, this is so for the ontologically real quantities, or beables.

** In the case of irreducible stochastic theories (for which no definition of locality holds ! "things happen" can be entirely conspirational), it is an extension of the concept of "local". **

Right, so the question is how the effective theory for the changeables more or less falls in that class.

**
So I was wondering how anyone could claim that nature is still local, measurements are still objectively happening events with unique outcomes, and perfect Bell tests are in agreement with quantum theory. **

Because things are only local for the ontologically REAL degrees of freedom - not necessarily so for those things we call particles.
The next task is to see how GR would fit in.

Concerning my analogy with the particles, I merely expressed by this the underlying thought that the stuff you are talking about is assumed to be real; hence satisfying the requirement of Bell locality when local realistic predicitons for that stuff are dismissed as being unable to surpass the Bell inequalities. So yes, the assumption ``particles are real'' creeps into the usual interpretation of the Bell inequalities although not in the mathematical formulation of it per se. I don't care either, ttn whether you consider waves, sockerballs or whatever; it is silly (and stupid) to presume that someone who says ``particles are assumed to be real'' does not know that the theorem applies to any real quantity you want to. So, if you have more in debth objections than this silly knit picking, you are welcome to provide them.

And ttn, if you think discussion is wrong, please adress your scientific objections directly to those whom you think are wrong. It is clear that you can change particles by whatever, but you still have to assume it to be REAL, which is the point you miss or do not want to see. Or perhaps you have a no go theorem for this proposal, in which case we would learn all something.

Careful

 

[RandallB]

So I was wondering how anyone could claim that nature is still local, measurements are still objectively happening events with unique outcomes, and perfect Bell tests are in agreement with quantum theory.

I agree that no theory currently gives a Local solution. The ignorance contained in probabilities is acknowledged by some as non-local within their theory via HUP, Guide Wave etc. Whatever works within that theory at least they acknowledge it as Non-Local.
I just disagree when the desire to claim Locality is reached by hiding the unknown probabilities or ignorance in some loosely defined stochastic mechanism like vacuum particle/antiparticle pair creation. For me that includes MWI-QM. I understand your careful use of quotes on the words realist and local in:

BTW, I would, for the n-th time, want to underscore that MWI-QM *IS* a local "realist" theory in agreement with Bell, in that it is "realist" (objective description of nature), it is "local" …..

Here the unknown uncertainty is tucked away in an alternate form of multidimensional reality with MWs that allowed to “pair up” worlds sometime after the A and B events in those that produce the correct correlations. That is an alternate version of reality you may call “reality” but until we have some conclusive objective demonstration that that kind of reality is correct I cannot accept it. As a local realist without quotation marks, for me MWI-QM is a "reality" that is still a non-local explanation.

I do believe the world is Local, but I’ve seen nothing here that would allow me to claim it as true. The term should be held to higher standard than has been the case, or at least some acknowledgment when a stochastic variation of Local is being claimed as “Local”.

 

[Careful]

**The ignorance contained in probabilities is acknowledged by some as non-local within their theory via HUP, Guide Wave etc. Whatever works within that theory at least they acknowledge it as Non-Local.
I just disagree when the desire to claim Locality is reached by hiding the unknown probabilities or ignorance in some loosely defined stochastic mechanism like vacuum particle/antiparticle pair creation. For me that includes MWI-QM. **

But QFT does not make the link to observed reality and MWI abandons the notion of one reality. But if you assume particles to be ontologically real, then what is your position (it seems you have only one option) ?

**
I do believe the world is Local, but I’ve seen nothing here that would allow me to claim it as true. The term should be held to higher standard than has been the case, or at least some acknowledgment when a stochastic variation of Local is being claimed as “Local”. **

So basically you hope for no Bell violating experiments I guess...

Careful

 

[ttn]

Concerning my analogy with the particles, I merely expressed by this the underlying thought that the stuff you are talking about is assumed to be real; hence satisfying the requirement of Bell locality when local realistic predicitons for that stuff are dismissed as being unable to surpass the Bell inequalities. So yes, the assumption ``particles are real'' creeps into the usual interpretation of the Bell inequalities although not in the mathematical formulation of it per se. I don't care either, ttn whether you consider waves, sockerballs or whatever; it is silly (and stupid) to presume that someone who says ``particles are assumed to be real'' does not know that the theorem applies to any real quantity you want to. So, if you have more in debth objections than this silly knit picking, you are welcome to provide them.

And ttn, if you think discussion is wrong, please adress your scientific objections directly to those whom you think are wrong. It is clear that you can change particles by whatever, but you still have to assume it to be REAL, which is the point you miss or do not want to see. Or perhaps you have a no go theorem for this proposal, in which case we would learn all something.
Careful

I meant no disrespect by not addressing you directly; I just don't think you understand this issue particularly well, and so I don't really want to spend time getting into a protracted discussion with you. All your comments about beables vs. "changeables" and what is and isn't ontologically real, etc., make no sense to me. Are you suggesting that something which is *not* "ontologically real" (a "changeable" as opposed to a beable??) plays some important role in the physics? And your idea of "explaining" the EPR type correlations with particle/antiparticle creation is just silly, and obviously wouldn't work. Or rather, to make it work, you would need nonlocality in the dynamics. But this is all just some pointless detail, since, contrary to what you seem to think, there is no assumption about the reality of particles (or whatever) needed to arrive at Bell's inequalities. Locality (specifically "Bell Locality") is *all* that is assumed. Don't believe me, though. Go study Bell's papers. You might want to pay special attention to section 4 of "Bertlmann's Socks..." where Bell specifically addresses the reader's possible worries that some other assumptions snuck in, and says things like "You might suspect that there is something specially peculiar about spin-1/2 particles. ... So the following argument makes no reference to spin-1/2 particles, or any other particular particles. Finally, you might suspect that the very notion of particle, and particle orbit, freely used in introducing the problem, has somehow led us astray. ... So the following argument will not m ention particles, nor indeed fields, nor any other particular picture of what goes on at the microscopic level. ... The difficulty is not created by any such picture or any such terminology..."

Or was your point supposed to be an objection against the very *idea* of considering some hypothetical/candidate description of "the real" -- i.e., were you objecting to the very idea of an independent external physical reality? If that, then you're right. You can't get a Bell Inequality without that. But who (other than maybe Rovelli and Smerlak, and inmates in mental institutions) would deny this?

 

[Farsight]

I'm sorry vanesch, I'm not clear on the point you wanted answered.

Careful:

In this way you never solve the measurement problem since you would need to explain the sudden collapse to a particle state.

I'm not sure what you're asking of me here. You can measure and/or annihilate the quantum at point X and therefore it appears to be all at point X, a point particle. But all you've really got is a "Phantom Jet" detector, which involves a very large concrete block, and a 500mph rocket driven sled.

http://www.fotosearch.com/PHD293/54334/

 

[RandallB]

But QFT does not make the link to observed reality and MWI abandons the notion of one reality.

I have no problem with those points -- it is part of what make them both non-local.

As for Bell I suspect he has made an error similar to the one by Von Neumann that Bell exposed as an error. But until I ready I'm ready with more than a personal belief and a suspicion I make no claims - it would belong in another thread anyway, not here.

 

[CarlB]

If you are a Bohmian, then you must be aware that there exists no -even remotely- convincing interpretation for QFT.

Okay.

Suppose that particles are all composites, and that in interactions, they are neither created nor destroyed, except in pairs of particle / antiparticle (and then only in virtual form). Then one can rewrite the usual particle interactions in terms of particles in a Bohmian fashion. That is, there will be no particle creation / annihilation, so the whole thing will look again like QM, a problem that Bohmian mechanics has provided a remotely convincing interpretation.

Under this assumption, QFT would be an effective theory which lies on top of a QM. This, in fact, was how QFT was first developed, by the condensed matter physicists in order to simplify Schroedinger's equation problems.

One of the attractions of string theory is that it takes the usual interactions between a fermion and a gauge boson and smears them out so that there is no single point where creation and annihilation operators would trade places. The above Bohmian interpretation does a similar thing. Every creation is accompanied by one and only one annihilation.

Now the primary disadvantage of the above is that I haven't provided the model of the preons that will give the standard model in Bohmian form. But hey, I'm working on it. http://www.snuark.com

The standard model is complicated. That does not mean that the underlying theory is also complicated. It means that the solutions are complicated. The great example of this tendency of nature is the simplicity of the Pauli extension of Schroedinger's equation and the complexity of the table of the elements.

Carl

 

[Careful]

**I meant no disrespect by not addressing you directly; I just don't think you understand this issue particularly well, and so I don't really want to spend time getting into a protracted discussion with you. **

I do understand the Bell inequalities quite well and adress your comments further below.


** All your comments about beables vs. "changeables" and what is and isn't ontologically real, etc., make no sense to me. Are you suggesting that something which is *not* "ontologically real" (a "changeable" as opposed to a beable??) plays some important role in the physics? **

Well, this is what the papers do suggest. Ok, let me admit that so far I have not seen any convincing classical mechanism to emerge from his attempts. What is done is that the determinstic dynamics is immediately given a Hilbert space description in which a *quantum constraint* is imposed to ensure the positivity of the Hamiltonian. Beables, in this setup, are operators that commute at all times, changeables do not commute with the latter; for example the Hamiltonian is a changeable. Quantum states are introduced as non-local, acausal equivalence classes of states in the classical dynamics which evolve after a sufficient amount to the same state. In order to ensure that the quantum states appear in much smaller number and that the resulting dynamics is unitary, the condition of information loss is added. Operators concerning particles, spin and so on are not beables. Now, concerning the Bell inequalities I have only seen so far comments which suggest predeterminism, questioning local rotational invariance (of the QM state) without affecting the state (as you know there is also the loophole of local rotation invariance in the Bell experiments) or some issues concerning the vacuum.

** And your idea of "explaining" the EPR type correlations with particle/antiparticle creation is just silly, and obviously wouldn't work. Or rather, to make it work, you would need nonlocality in the dynamics. **

No, there are several possibilities : predeterminism (which could amount to abandoning local rotation invariance), or one could allow the virtual particle/antiparticles to travel FTL (which would violate Bell locality, but not locality).

** But this is all just some pointless detail, since, contrary to what you seem to think, there is no assumption about the reality of particles (or whatever) needed to arrive at Bell's inequalities. Locality (specifically "Bell Locality") is *all* that is assumed. **

It is not that simple : Bell locality does not imply the Kolmogorov property which is the assumption which I questioned (and which is actually the only thing needed + dichotomic outcomes). As mentioned before, predetermism can violate the Bell inequalities since it breaks the Kolomogorov property, but involves no FTL.

**
Or was your point supposed to be an objection against the very *idea* of considering some hypothetical/candidate description of "the real" -- i.e., were you objecting to the very idea of an independent external physical reality? If that, then you're right. You can't get a Bell Inequality without that. But who (other than maybe Rovelli and Smerlak, and inmates in mental institutions) would deny this? **

Euh, as far as I know, S. Adler has figured out a non-local deterministic mechanics whose statistical mechanics reproduces QM. So it is seems very possible to have a candidate prescription of the real (but not a local one). An interesting paper on free will versus determinism is written by Kochen and Conway : quant-ph/0604079

 

[vanesch]

That is absolutely false. To say that all probabilities are descriptions of ignorance, is to say that one insists on determinism -- i.e., that one is unwilling to accept the possibility of an irreducibly stochastic theory. This is just simply wrong as a description of Bell's assumptions. Bell does *not* assume determinism, as he stressed over and over again in his later papers (because people kept insisting that his derivation relied on determinism).

I know that Bell says that. But there are 2 points I wanted to make, one over which we went already many times.
I think that the first point is easy and you'll agree with me:
IF the lambda in Bell's argument IS entirely determining the outcomes, so that the P(A,B|a,b,lambds) are all 1 or 0 (in other words, IF the theory is deterministic) THEN, this function being a complicated way of writing the deterministic dynamics, if that dynamics is local (in the usual sense for a deterministic theory), then Bell locality follows.

The second point is what I called jokingly - a long time ago - Patrick's theorem:
If the theory is NOT deterministic, but follows Bell locality, then one can always EXTEND the theory, by adding "beables" into lambda, to make it into a local, deterministic theory, with the same predictions.

As such, I consider that we can limit ourselves to deterministic theories EVEN IF THAT WAS NOT BELL'S INTENTION.

You make no error by assuming that lambda specifies entirely the outcome (even if in a particular theory you're considering, it doesn't). If a theory is Bell local, and "irreducibly stochastic", you can swap it for a theory which is deterministic, and of which all probabilities are hence probabilities of ignorance of what lambda might be.

To make it more precise, you should say: the probability *that an irreducibly stochastic theory attributes to* something happening at event A is entirely determined by what is in A's past lightcone. The probabilites in "Bell Locality" are *not* epistemic -- they are the fundamental dynamical probabilities that some candidate stochastic theory assigns to things. And what Bell Locality amounts to is the requirement that these probabilities be based on (as, for example, the probabilities in OQM are based on the wave function) stuff/events/beables in the past light cone of the event in question. The probabilities assigned to an event in a Bell Local theory do not depend on stuff outside the past light cone.

Yes, but, as I said, we can now even extend the theory as becoming deterministic, with these probabilities now purely epistemic (about our ignorance of the value of these extra variables, which you called the "stochastic variables" in the previous one, and raised to the rank of beables in the new theory), and we would get exactly the same predictions, and this new, deterministic theory would be entirely local (in the usual sense of the word, which has a meaning for deterministic theories).

It's no more or less an assumption than the definition of "local" for deterministic theories. It's just a more general definition of "local".

Yes, that's all I said: it is an EXTENSION of the concept of local. But - as we discussed already many times before - as much as local for a deterministic theory is entirely clear, with probabilities one has to be careful, because they are not really physical quantities (fields over spacetime, say). An event A can have a certain probability P(A), and after it happened, this reduces to 0 or 1. So P(A) is not really a physical value that can be assigned to a spacetime point, as can, for instance, a temperature or something. P(A) not being a physical field, and always having an epistic component to it, it is not entirely evident how to extend the definition of local to a stochastic theory. However, I'd concur that the Bell definition is by far the most obvious and natural extension of it. I grant that and I do not dispute its reasonableness. But we have to be aware that, outside of the framework of a strictly deterministic theory, the concept of "locality" is not really defined, and hence a choice is to be made.

What I wanted to point out simply is that Bell locality (which is such an extension of the definition of locality, and hence always has some arbitrary component to it over which one can discuss) COINCIDES with the usual word local, when the underlying theory is deterministic and all probabilities are epistemic. And, moreover, in those cases where the underlying theory is not deterministic, we can MAKE it deterministic and still keep locality (in the usual sense) ; that's "Patrick's theorem".

So I READ Bell - even though he didn't have this in mind - as:

The experimental outcomes (or predictions) are COMPATIBLE with an underlying DETERMINISTIC, local theory.

I know that was not the original intention of Bell. If you want to, you can see it as kind of a coincidence, that, using the extension of the concept of local to include stochastic theories, that if such a stochastic theory satisfies it, it can be extended into a deterministic theory that is (normally) local.
If it is seen this way, then this is a rather unfortunate fact, because now the distinction between "fundamentally stochastic but Bell local" and "potentially underlying deterministic and local" is spoiled for ever, them being (by coincidence) equivalent statements.
But coincidence or not, they ARE equivalent statements.

But instead of whining over this (unfortunate) equivalence, which goes against the spirit of Bell, we can take it as an advantage. The nice thing about this is that you even don't have to have the theory. You just have to check whether the Bell conditions hold.
On data, or on the stochastic predictions of any theory. IF the Bell conditions hold (on the DATA or PREDICTIONS, not on the supposed machinery of a hypothetical theory), then these DATA OR PREDICTIONS can also be reproduced by a (potentially ugly) local deterministic theory. If not, then you won't find ANY such local deterministic theory, and hence also no Bell-local stochastic theory.

That's Bell's "lambda". (Completeness is of course defined by whatever particular candidate theory one is assessing.) To say that the probabilities in Bell Locality (which are always conditional on this lambda) are ignorance-based is to say that, really, there is some unknown fact which *determines* outcomes, but which is not contained in lambda (hence we only have probabilities, not determinate predictions). But this is all contradictory. That lambda provides a complete state description is *assumed*. You can't just come back later and say "well maybe really it doesn't, and the probabilites are really ignorance-based rather than fundamental". To say that is not some kind of objection to bell's locality criterion -- it's simply to change midstream what theory one is talking about. And if you're too scatterbrained to keep thinking about the same theory through the whole analysis, don't blame it on bell!

No, what I showed, long ago, is that you can EXTEND the lambda of any Bell local theory so as to make it completely deterministic, and that Bell locality is conserved under this operation. Whether you find this an attractive option, and whether the theory resulting has any esthetical or physical appeal is another matter, but it can be done.

So, again, I'm not making any REQUIREMENT of determinism. Maybe I formulated this badly, I didn't want to mean that Bell insisted on determinism. I'm just saying that the way Bell extended the concept of local (which holds for deterministic theories) to stochastic theories, AUTOMATICALLY IMPLIES that a deterministic, local theory is compatible with the predictions.

So, AFTER THE FACT, whether it was intended or not, Bell locality for stochastic theories is EQUIVALENT to requiring the potential of an underlying deterministic local theory.

As such (and probably my wordings were unfortunate), IT IS NOT A RESTRICTION to say that probabilities are ignorance-based in the discussion of Bell locality. Because even if initially they weren't thought to be so (and the theory was irreducibly stochastic), we can swap them for being so (and the NEW, equivalent, theory is now deterministic). So, when talking about Bell locality, there's no NEED (it is not a requirement) to talk about non-epistemic probabilities.
BTW, I have serious conceptual difficulties, as I told you already, with the concept of non-epistemic probabilities, without saying: "things happen". But happily, this concept is NOT NEEDED to discuss Bell's stuff. I'm not saying that it is a RESTRICTION. It is a CONSEQUENCE of the way Bell defined locality for stochastic theories.

And all this was not the point I wanted to make. I wanted to make the point that, PURELY HAVING A SET OF DATA, or HAVING A SET OF PREDICTIONS FROM A BLACK BOX, one can check them against the Bell inequalities. If they don't satisfy these, then THERE IS NO HOPE of finding *either* a Bell-local stochastic theory, OR an underlying local deterministic theory (both being equivalent).

This is because claims were made that the Bell inequalities were somehow based upon underlying physical assumptions of the existence of particles or so. Not at all. A set of DATA, from an experiment, can tell you whether, yes or no, there is ANY HOPE of obtaining them from a Bell-local stochastical theory, or from an underlying deterministic local theory. You do not have to make any assumptions of the physical nature of the cause of these data in order to establish this.
It would constitute a perfect Bell test.

The assumption of particles IS however made in NON-perfect Bell tests as they have been performed up to now, in order to CORRECT for the data (the "efficiency of detection" being intrinsically a particle-related concept).
This is why stochastic electrodynamics can still succeed in making equivalent predictions of the current non-perfect Bell tests. But the day that we will have data from a perfect Bell test, and where these corrections are not needed anymore, we don't need any assumption of particle or whatever in order to check the Bell inequalities. If they are violated, then we know that NO WAY these data are going to come out of a Bell-local stochastic theory, or out of a deterministic local theory.

 

[vanesch]

No, there are several possibilities : predeterminism (which could amount to abandoning local rotation invariance), or one could allow the virtual particle/antiparticles to travel FTL (which would violate Bell locality, but not locality).

If the mechanism is deterministic, then it is clearly non-local: something is traveling faster than light. If the theory is stochastic, then you are disputing the extension of the concept "local" (which has initially only a meaning for deterministic theories) the way Bell did it to "Bell-local".

So in fact you change the definition of "local" from the way Bell did it, for a stochastic theory. One has to be careful when doing that, not to end up with a definition which includes also faster-than-light telephones as being local, as do Rovelli and Smerlak for instance.

 

[vanesch]

[about MWI]
Right, which is why its predictions -- for what *actually happens* -- do not violate the inequalities. Of course, it also "predicts" that observers are systematically deluded into believing that there were definite measurement results at A and B, and that these delusional/fantasy results violate the inequalities. But since that is just delusional fantasy, and not the real state of things, there's no point talking about it.

Well, yes, I couldn't formulate it any better myself. I do not feel comfortable with this myself, you know, but of all options, it is the one I prefer. Having been deluded about so many things in my life , if my choice is:
1) I have to give up the assumption of an existing reality
2) I have to give up the assumption of locality (and hence of relativity)
3) I have to assume that I'm deluded about what reality is

then my personal experimental experience tells me that 3) is by far the most probable candidate :rofl:

Now, the day that another theory comes along which explains all these things (including relativity) in a natural way, we can dispose of being deluded.

 

[Careful]

**If the mechanism is deterministic, then it is clearly non-local: something is traveling faster than light. If the theory is stochastic, then you are disputing the extension of the concept "local" (which has initially only a meaning for deterministic theories) the way Bell did it to "Bell-local". **

(Corrections of terminology, sorry for this) Bell's definition of stochastic locality is fine (if it is not taken to imply the latter two conditions), however the no correlation assumption as well as the no conspiracy condition (known not to be satisfied in QFT) seem naive (especially in theories with random fields (!) such as is the case in thermal equilibrium states) - arguments for its defense can easily be logically turned against him, check out the paper of Morgan I cited before, replace here the variables a,b,c by what I called particle *measurements* (real ``no- hidden'' variables) and lambda, mu, nu by a set of possible Planckian oscillations (the real hidden variables), follow the argument and you will see what I meant before.
The Planckian observer sees a local word while the non-planckian observer does not; this is possible depending on your definition of particle (as a coarse grained concept) as well as on the correlations in the vacuum state for the Planckian degrees of freedom. The entire difficulty is of course to find a natural Planckian model, as well as a suitable definition of particle such that the vacuum state arises naturally as well as the predictions of QM do.


**
So in fact you change the definition of "local" from the way Bell did it, for a stochastic theory. One has to be careful when doing that, not to end up with a definition which includes also faster-than-light telephones as being local, as do Rovelli and Smerlak for instance. **

I do not know about Rovelli and Smerlak, but yes, the constraint - no information can travel faster than light (note : this will severely depend upon your notion of information itself) - will certainly chop away lots of possible models

To put it more to the edge, IF you take the idea of classical local evolution seriously as well as the idea of initial lack of knowledge of the state, then the notion of no conspiracy/no correlation is highly unnatural.

Cheers,

Careful

 

[Careful]

Well, yes, I couldn't formulate it any better myself. I do not feel comfortable with this myself, you know, but of all options, it is the one I prefer. Having been deluded about so many things in my life , if my choice is:
1) I have to give up the assumption of an existing reality
2) I have to give up the assumption of relativity (and hence of relativity)
3) I have to assume that I'm deluded about what reality is

then my personal experimental experience tells me that 3) is by far the most probable candidate :rofl:

Now, the day that another theory comes along which explains all these things (including relativity) in a natural way, we can dispose of being deluded.

:rofl: :rofl: You simply have to accept that non-local correlations have been build up by a local dynamics which are not entirely washed away (as Bell hopes), and cause these appearantly strange phenomena. Then, no blatant contradiction arises.

Careful

 

[ttn]

Well, yes, I couldn't formulate it any better myself. I do not feel comfortable with this myself, you know, but of all options, it is the one I prefer. Having been deluded about so many things in my life , if my choice is:
1) I have to give up the assumption of an existing reality
2) I have to give up the assumption of locality (and hence of relativity)
3) I have to assume that I'm deluded about what reality is

then my personal experimental experience tells me that 3) is by far the most probable candidate :rofl:

Just for the record, you're aware that the "rolling" in the rofl matches perfectly the structure of the logic here: everything you've seen with your eyes all your life convinces you that the best option is to reject as fantasy/delusion what you see with your eyes...

 

[Careful]

**
Suppose that particles are all composites, and that in interactions, they are neither created nor destroyed, except in pairs of particle / antiparticle (and then only in virtual form). Then one can rewrite the usual particle interactions in terms of particles in a Bohmian fashion. That is, there will be no particle creation / annihilation, so the whole thing will look again like QM, a problem that Bohmian mechanics has provided a remotely convincing interpretation. **

As far as I recall, the defined worldlines are not Lorentz invariant, i.e. frame dependent; it seems impossible to me to reconcile that with any notion of objective reality. It is also clear that interactions change the particle number, I guess you would have to introduce then a stochastic element in the dynamics which is again dependent upon your choice of foliation as well as a seemingly (limited) ad hoc choice of *when* the particles of the incoming species disappear and the others appear. Or is there some way to avoid these issues recently ?

Careful