Entanglement spooky action at a distance

[vanesch]

The burden would be on the developer of this hypothesis to provide some explanation of how that might work. Thus, I will critique an actual superdeterministic theory once there is one.

Yes, and my point is in fact, that I don't even see how such a superdeterministic theory could even be shown to work. What's proposed would be to demonstrate, through a mathematical theorem of relative simplicity (say, less than 200 pages :-) that the proposed local dynamics is "equivalent" to quantum mechanics - I suppose a bit such as the proof that BM is equivalent to quantum theory, that must be what proponents of looking for a superdeterministic theory are hoping for.
But I don't see how that could be the case, because in normal quantum mechanics (as in BM for instance) you impose *externally* that Joe is going to measure along theta1 and Jane along theta2. You PUT IN BY HAND the experimental choice.

The superdeterministic theory, on the other hand, gets its "superdeterminism" from the fact that with given initial conditions (and according to 't Hooft, these don't even have to be exceptional) and the proposed dynamics, Joe can't do anything else but pick theta1, and Jane can't do anything else but pick theta2. So the class of possible situations described by quantum theory is much larger (you could pick all pairs theta1 and theta2) than the class of situations described by the superdeterministic theory (which, of course, according to that theory, are the only ones that are actually possible): just one pair (theta1,theta2) or maybe just a limited set (theta1,theta2).

So there cannot be a simple theorem that demonstrates in all generality that both are equivalent: our superdeterminist must show WHAT pairs will result from the dynamics. And to do that, he will have to work out in all detail how these angles are picked, and as there are remote stars, brains, or computers with all thinkable algorithms in the loop, he would have to follow through all details there - which is FAPP impossible.

 

[wawenspop]

Entanglement & Bell's Theorem

Bells Inequality:
Lets say there is a hidden variable implanted in each
entangled particle at 'birth', - for one it defines
'I am an upspinner' and the other 'I am a downspinner'.

This is held in a secret compartment to be revealed only
when the particles are observed.

So, we work out probablities and test accordingly to that theory,
and the results we get, show, that this theory cannot be correct.

Then QM gives us a slightly different answer because its not using a
hidden variables theory - QM obeys 'We have no exact spin, either of us,
until we are observed, then we use probablity to give you your results'.
This scenario produces a slightly different result on testing,
- and is the one we actually get. (so hidden variables cannot be correct)

Bell's Theorum is showing us that particles are in 'both states' until observed
is what is happening, rather than - 'there are hidden variables controlling these
observables'.



- (maybe hidden complex functions might do the trick!)

 

[vanesch]

- (maybe hidden complex functions might do the trick!)

Nope, there is no requirement on the "container" of the "hidden" information - well, there's one: it needs to be from a measurable space over which a probability measure can be defined.

 

[ueit]

I think you can figure this out as easily as anyone: IF Locality holds (the point of positing Superdeterminism in the first place) AND initial conditions control the ultimate outcome, THEN the outcome of every future experiment that is to be run must be present in every local area of the universe (so that the results correlate when brought together). The burden would be on the developer of this hypothesis to provide some explanation of how that might work. Thus, I will critique an actual superdeterministic theory once there is one.

Yes, and my point is in fact, that I don't even see how such a superdeterministic theory could even be shown to work. What's proposed would be to demonstrate, through a mathematical theorem of relative simplicity (say, less than 200 pages :-) that the proposed local dynamics is "equivalent" to quantum mechanics - I suppose a bit such as the proof that BM is equivalent to quantum theory, that must be what proponents of looking for a superdeterministic theory are hoping for.
But I don't see how that could be the case, because in normal quantum mechanics (as in BM for instance) you impose *externally* that Joe is going to measure along theta1 and Jane along theta2. You PUT IN BY HAND the experimental choice.

The superdeterministic theory, on the other hand, gets its "superdeterminism" from the fact that with given initial conditions (and according to 't Hooft, these don't even have to be exceptional) and the proposed dynamics, Joe can't do anything else but pick theta1, and Jane can't do anything else but pick theta2. So the class of possible situations described by quantum theory is much larger (you could pick all pairs theta1 and theta2) than the class of situations described by the superdeterministic theory (which, of course, according to that theory, are the only ones that are actually possible): just one pair (theta1,theta2) or maybe just a limited set (theta1,theta2).

So there cannot be a simple theorem that demonstrates in all generality that both are equivalent: our superdeterminist must show WHAT pairs will result from the dynamics. And to do that, he will have to work out in all detail how these angles are picked, and as there are remote stars, brains, or computers with all thinkable algorithms in the loop, he would have to follow through all details there - which is FAPP impossible.

OK, let me present my understanding of how a superdeterministic theory might be developed and verified against standard QM.

1. Requirements

The theory must necessarily contain a long-range force, otherwise it cannot elude Bell's theorem. Maxwell's theory or Einstein's theory of gravity are such theories. We also want that force to be local. Probably, that long-range force should not decrease with the distance, something like the quantum force of Bohm's theory.

The theory must give a clear mathematical description of the emission process so that one can quantitatively relate the spin of the entangled particles to the dynamics of the entire system.

2. Development and testing

The only way to actually see the theory in action is, IMO, a computer simulation. In order to be able to do the simulation in a short enough time one must find the most simple microscopic EPR test. For example we could start with an "universe" that only contains an atom in an excited state (source) and two molecules that can absorb the emitted photons (detectors) so that we could speak about a sort of measurement taking place.

The initial states of the "source" and "detectors" given, one could calculate the probability of the "source" to emit, and also the measurement results. By integrating over all possible initial states one should recover both the probability of emission as given by QM and also the prediction regarding the Bell tests

If such a theory is indeed possible one could then try to make statistical generalizations so that experiments involving stars or brains could be covered. However I don't see this as extremely important as even the standard QM cannot be verified on systems containing more than a few particles because of computational problems.

 

[DrChinese]

If there is a time difference between the first being detected and the second, what happens to the second one? Is it also 'collapsed' but still moving? My head hurts...

There is no apparent difference in the outcome if Alice is observed before Bob, or vice versa. Or if they are observed "simultaneously" (if that were possible) for that matter. Now I say no apparent difference because as it happens: the QM prediction is the same either way. There might be a difference - we don't know - but there is none detected (so far) in experiments and none predicted by theory.

So to answer your question, there is no obvious change to the behavior of Bob after an observation of Alice (assuming Alice observed first). Both entangled photons behave as predicted; observation of Alice causes Bob to act "as if" a message had been instantaneously been sent letting Bob know what the result of the Alice observation was - so Bob could act accordingly. Now, I said "as if" because I have no idea if anything like this actually happens. The actual mechanism has eluded the minds of physicists. Every hypothesis has problems of one kind or another, and there is no real consensus.

 

[peter0302]

Bell Realism is the assumption that a particle has a specific property independent of the act of observing that property. To paraphrase Einstein's words, the moon is there even when I am not looking at it. Although Bell did not use the word "vital" to describe it, it is just as important to the paper as Bell Locality is. They are not the same thing, and they are expressed differently in the proof.

Where are they expressed differently? Recall in my "easy version" proof, the only assumption you need is:

A = AB + Ab

or "what happens at A is independent of what happens at B".

How are "locality" and "realism" distinct in that assumption?

 

[DrChinese]

OK, let me present my understanding of how a superdeterministic theory might be developed and verified against standard QM.

1. Requirements

The theory must necessarily contain a long-range force, otherwise it cannot elude Bell's theorem. Maxwell's theory or Einstein's theory of gravity are such theories. We also want that force to be local. Probably, that long-range force should not decrease with the distance, something like the quantum force of Bohm's theory.

The theory must give a clear mathematical description of the emission process so that one can quantitatively relate the spin of the entangled particles to the dynamics of the entire system.

I think you are seeing the basic issues... entirely new mechanisms are required and once their assumptions are spelled out, it will be clear that the result is an ad hoc theory with a lot of baggage. Here is an example of the difficulty:

I. The Experiments

Experiment A: I simply hold Alice and Bob's observations at a 120 degree difference (i.e. static, no change from one reading to the next) and collect a sample of 10,000 readings. No choice is involved, at least from trial to trial. I expect the results to be a correlation rate of .25 as predicted by QM.

Experiment B: I set Alice and Bob's observations at a 120 degree difference (but dynamically, in which I personally "randomly" choose between whether the difference is to be +120 or -120 degrees by changing the orientation only of Bob's apparatus) and collect a sample of 10,000 readings. I expect the results to be a correlation rate of .25 as predicted by QM.

Experiment C: I force Alice and Bob's observations to be at a 120 degree difference by a dynamic mechanism (described in next paragraph) - choosing between whether the difference is +120 or -120 degrees by again changing the orientation only of Bob's apparatus -and collect a sample of 10,000 readings. I expect the results to be a correlation rate of .25 as predicted by QM.

This dynamic mechanism is as follows: I use a radioactive sample to generate random numbers. Say I use an algorithm based on the time of detection of the radioactive particle. If it ends in an even number then I set at +120 degrees, if an odd number I set at -230 degrees. This is done while Alice and Bob are in flight. Therefore, there is no possibility of an FTL influence.


II. Discussion of Issues

What are the issues here? All of the results are identical, as predicted by QM. But the Superdeterministic theory must now explain HOW that is possible because the conditions are being varied, in effect, by placing an experimental "barrier" between the initial time T=0 and the time of the actual test. Since A, B and C have different ways that the choice is made for the observation, we need the superdeterministic theory to explain how these 3 variations end up with identical results. This is also true for an infinite (or at least a large :) number of other variations (D,E,F...) that you or I can dream up.

So: how do the initial conditions NOT change the outcome when radioactivity (a random quantum process) is responsible for the selection of the measurement settings? Gee, there must be a causal connection between the radiation and the algorithm I am using to key off of as well. Then we now have a pretty big conspiracy going on between the different forces, quantum events and macroscopic objects as well, if we are to get the desired results.

Since the distant results are to be correlated, the hypothetical causal connection is contained locally too. So all of this must be hiding somewhere in Alice and Bob; i.e. there must be information contained within these photons. And yet, the photons didn't even exist before they were created in the source laser.


III. Conclusion

So it should be clear that any proposed solution will suffer from an extreme case of ad hoc description which becomes very complicated very quickly. I don't think this is useful, and I don't think we are any longer talking about Bell's Theorem. And I don't think the theory we arrive at could withstand the objective assault that it would be subjected to. As I said to begin with, we could just as easily postulate that God personally tricks us into witnessing the results by biasing Bell tests... and this is just as reasonable (or unreasonable) as any Superdeterministic theory.

 

[DrChinese]

Where are they expressed differently? Recall in my "easy version" proof, the only assumption you need is:

A = AB + Ab

or "what happens at A is independent of what happens at B".

How are "locality" and "realism" distinct in that assumption?

Actually, A=AB + Ab is measured and need not be assumed.

What needs to be assumed is that AB = ABC + ABc as that is what fails. That is the Realism requirement. So you might also express that in your terms by saying that A = AB + Ab for all A, B, C... simultaneously. There is no C in QM, which in Einstein's mind meant that QM was incomplete.

The Locality requirement is that f(A) = f(A|B) i.e. that the A result is not dependent on the B setting; and vice versa. This has been experimentally ruled out for forces propagating at c or less.

 

[vanesch]

OK, let me present my understanding of how a superdeterministic theory might be developed and verified against standard QM.

1. Requirements

The theory must necessarily contain a long-range force, otherwise it cannot elude Bell's theorem. Maxwell's theory or Einstein's theory of gravity are such theories. We also want that force to be local. Probably, that long-range force should not decrease with the distance, something like the quantum force of Bohm's theory.

?? If there is a long-range force that's going to do the thing, then it is not local, right ? The quantum force in BM is not local, Newtonian gravity is not local, electrostatics is not local. What is local is a local field propagation equation, like Maxwell's equations or Einstein's equations. If you allow for long-range forces, then you don't NEED superdeterminism, as Bell isn't supposed to hold in that case. No, the only thing that is allowed are local interactions. That's what makes superdeterminism so hard to handle: the correlations must arise through a whole chain of local interactions from a certain "common initial state" up to the actual manifestation of the correlations, through the precise tuning of the "choices" of measurement in agreement with the particular sets of particles that have been emitted.

The theory must give a clear mathematical description of the emission process so that one can quantitatively relate the spin of the entangled particles to the dynamics of the entire system.

Yes, but also with the measurement process!

2. Development and testing

The only way to actually see the theory in action is, IMO, a computer simulation. In order to be able to do the simulation in a short enough time one must find the most simple microscopic EPR test.

In fact, that wouldn't be ok. In order for superdeterminism to hold, it must also do it in *the most complicated EPR test possible*.

For example we could start with an "universe" that only contains an atom in an excited stat. e (source) and two molecules that can absorb the emitted photons (detectors) so that we could speak about a sort of measurement taking place.

That would be a start, but then you'd have to show that those molecules appear in exactly those orientations, each time, to measure the photons along the right axis, each time. And then you must show that WHATEVER I ADD, that this is not going to change this. *this* is, IMO, the impossible task of showing superdeterminism.

Because it would be sufficient to find one single system that doesn't orient the "detecting molecules" in exactly the anticipated way, to undo the entire system. Now, I know your objection to that: something like "conservation of energy" is superficially in the same situation, and we don't have to follow up on all possible engines to show the first law of thermodynamics. But there's a difference. In things like conservation of energy, there is a clear physical parameter which is conserved by each interaction, and hence, also overall. I don't see how one could introduce something like "conservation of choice" that makes that *this* photon, no matter how, is going to be analysed only with *that* analyser angle. If ever such a thing existed, it would mean we would have a relatively simple "thermodynamics of (non)free will" in all generality.

If such a theory is indeed possible one could then try to make statistical generalizations so that experiments involving stars or brains could be covered. However I don't see this as extremely important as even the standard QM cannot be verified on systems containing more than a few particles because of computational problems.

No, there's a big difference. In QM, or classical physics, we *don't have to* follow up through all the nitty gritty detail, because it doesn't involve the *essential effect*. If a photon is detected with a PM, well, that PM is going to generate a signal and all that, and this is going to be recorded etc... but we don't need the details here because they don't matter. They don't compose the essential effect we are observing (detecting a photon). So this can be abstracted away without any difficulty.

However, if the process that makes Joe choose angle th1 is the essential mechanism, this is different.

 

[Count Iblis]

The superdeterministic theory, on the other hand, gets its "superdeterminism" from the fact that with given initial conditions (and according to 't Hooft, these don't even have to be exceptional) and the proposed dynamics, Joe can't do anything else but pick theta1, and Jane can't do anything else but pick theta2. So the class of possible situations described by quantum theory is much larger (you could pick all pairs theta1 and theta2) than the class of situations described by the superdeterministic theory (which, of course, according to that theory, are the only ones that are actually possible): just one pair (theta1,theta2) or maybe just a limited set (theta1,theta2).

Yes, one has to assume here that there exists some set of allowed set of initial conditions that will yield the predictions of quantum mechanics, including the violations of Bell's inequalities. That in turn implies that the counterfactual situations cannot exist. But it doesn't really imply that you couldn't have choosen any other setting for the polarizers. It simply means that if you had done that then many other things would necessarily also be different in such a way as to have affected the outcome of the experiments. So, the choice of the polarizer's setting would be correlated with the system.

Now, counterfactual situations are problematic in general, but since we assume that what we decide to measure can be considered to be uncorrelated with the system's state, we can pretend as if the counterfactuals do exist.

We know that the early universe was in a low entropy state. If we were to replace the exact microstate the universe is in today by a randomly chosen microstate corresponding to the same macro state, then evolving it back in time would lead to the entropy increasing (with almost 100% probability). So, that state cannot have evolved from any physically acceptable initial conditions at all.

When we do experiments at the macro level, this is not relevant, because for each macro state (counterfactual or not) you can find many micro states with acceptable initial conditions. But at the micro level, this may no longer be the case.

 

[peter0302]

I think you can figure this out as easily as anyone: IF Locality holds (the point of positing Superdeterminism in the first place) AND initial conditions control the ultimate outcome, THEN the outcome of every future experiment that is to be run must be present in every local area of the universe (so that the results correlate when brought together). The burden would be on the developer of this hypothesis to provide some explanation of how that might work. Thus, I will critique an actual superdeterministic theory once there is one.

I got it. Quantum DNA. The past and present history of every particle in the universe is encoded in every particle. There's your hidden variable.

This isn't as far-fetched as it sounds if each elementary particle is a single 4 dimensional line as Wheeler thought.

 

[RandallB]

I got it. Quantum DNA. The past and present history of every particle in the universe is encoded in every particle. There's your hidden variable.

This isn't as far-fetched as it sounds if each elementary particle is a single 4 dimensional line as Wheeler thought.

IMO it still does not address the issues in the last paragraph of both DR C post # 117 & my Post #118: i.e. still farfetched.
Since a Wheeler 4 dimensional line cannot be Local and Realistic, it would be a Non-Local hidden variable.

 

[peter0302]

Yes it's far-fetched but no more so than any other interpretation.

It's still local in the sense that there is no communication going on faster than light - there's no communication at all because every particle is one.

And it's actually hyper-realistic because there is a defined value for every particle throughout all of time and space.

Look I'm not saying I think this is true and am certainly not advocating it, I'm just saying that if you want a superdeterministic interpretation that is at least stateable, there it is.

 

[DrChinese]

I got it. Quantum DNA. The past and present history of every particle in the universe is encoded in every particle.

Now all we have to do is read it and we will know everything that is to come. :)

Obviously, everything else we know about elementary particles indicates they have no internal structure and do not have well-defined non-commuting properties outside of an observation. So "quantum DNA" is conceptually possible but little more. As I said, a specific theory would almost certainly be falsifiable. The concept only works as long as it is jelly - i.e. no specifics to critique.

 

[peter0302]

Of course you're right. The vaguer the better when it comes to interpretations. I guess that's why Copenhagen is so successful. :)

 

[vanesch]

I got it. Quantum DNA. The past and present history of every particle in the universe is encoded in every particle. There's your hidden variable.

Yes, that's what I call "god's book". "things happen".

 

[RandallB]

Yes it's far-fetched but no more so than any other interpretation.

It's still local in the sense that there is no communication going on faster than light - there's no communication at all because every particle is one.

And it's actually hyper-realistic because there is a defined value for every particle throughout all of time and space.

Look I'm not saying I think this is true and am certainly not advocating it, I'm just saying that if you want a superdeterministic interpretation that is at least stateable, there it is.

but it is Not “stateable” as a Local interpretation unless you ignoring what people mean when they say and hear “Local”.
They don’t mean local as in locality alone. They mean Local as in EPR Local requiring locality, and realism which includes causality.
And a hyper-realistic “DNA” does not qualify as EPR realism. IMO super-deterministic determinism cannot be presented as Local unless you redefine Local into something different than the EPR Local expected when that term is used.
To declare an interpretation requires a hyper-realistic version of realism defines it as Non-Local in any meaningful understanding related to EPR.

 

[peter0302]

Right I see what you're saying. There really is no such thing as causation in a quantum DNA theory or really any superdeterministic theory that I can imagine. The very idea of causation means that something different could have happened than what did, which would be impossible if everything's already been set in spacetime.

 

[ueit]

I think you are seeing the basic issues... entirely new mechanisms are required and once their assumptions are spelled out, it will be clear that the result is an ad hoc theory with a lot of baggage. Here is an example of the difficulty:

I. The Experiments

Experiment A: I simply hold Alice and Bob's observations at a 120 degree difference (i.e. static, no change from one reading to the next) and collect a sample of 10,000 readings. No choice is involved, at least from trial to trial. I expect the results to be a correlation rate of .25 as predicted by QM.

Experiment B: I set Alice and Bob's observations at a 120 degree difference (but dynamically, in which I personally "randomly" choose between whether the difference is to be +120 or -120 degrees by changing the orientation only of Bob's apparatus) and collect a sample of 10,000 readings. I expect the results to be a correlation rate of .25 as predicted by QM.

Experiment C: I force Alice and Bob's observations to be at a 120 degree difference by a dynamic mechanism (described in next paragraph) - choosing between whether the difference is +120 or -120 degrees by again changing the orientation only of Bob's apparatus -and collect a sample of 10,000 readings. I expect the results to be a correlation rate of .25 as predicted by QM.

This dynamic mechanism is as follows: I use a radioactive sample to generate random numbers. Say I use an algorithm based on the time of detection of the radioactive particle. If it ends in an even number then I set at +120 degrees, if an odd number I set at -230 degrees. This is done while Alice and Bob are in flight. Therefore, there is no possibility of an FTL influence.


II. Discussion of Issues

What are the issues here? All of the results are identical, as predicted by QM. But the Superdeterministic theory must now explain HOW that is possible because the conditions are being varied, in effect, by placing an experimental "barrier" between the initial time T=0 and the time of the actual test. Since A, B and C have different ways that the choice is made for the observation, we need the superdeterministic theory to explain how these 3 variations end up with identical results. This is also true for an infinite (or at least a large :) number of other variations (D,E,F...) that you or I can dream up.

So: how do the initial conditions NOT change the outcome when radioactivity (a random quantum process) is responsible for the selection of the measurement settings? Gee, there must be a causal connection between the radiation and the algorithm I am using to key off of as well. Then we now have a pretty big conspiracy going on between the different forces, quantum events and macroscopic objects as well, if we are to get the desired results.

The mistake in your line of reasoning is related to the scale you use to look at these experiments. The hypothetical local-deterministic law of motion is defining the dynamics at plank scale, not at the macroscopic scale.

We have good evidence that the electromagnetic, weak and color forces are but manifestations of the same fundamental interaction. We should therefore expect the same dynamics at Plank scale for every type of standard-model particle. This law of motion at Plank scale should therefore describe in a similar way uranium, silicon or carbon atoms and any combination of them like rocks, humans, computers and so on.

Seen from a macroscopic point of view each "different" experimental setup is the quantum analogous of different galaxies in general relativity. We shouldn't expect a different law of gravity for each type of galaxy or for each type of massive object (stars, neutron stars, planets, gas clouds, etc.). Why do you think we should expect a different behavior at Plank level when the microscopic attributes of the object change?

Since the distant results are to be correlated, the hypothetical causal connection is contained locally too. So all of this must be hiding somewhere in Alice and Bob; i.e. there must be information contained within these photons. And yet, the photons didn't even exist before they were created in the source laser.

The causal connection is "hiding" in the interactions between the particles contained in the source and detectors. The particle configuration in the detector (including whatever is supposed to change its orientation) produces a specific local field and this field determines the motion of the electron that later will emit the photons. Of course, a quantitative calculation of such a complex system will probably remain intractable for a very long time but this is also true for the standard QM.

III. Conclusion

So it should be clear that any proposed solution will suffer from an extreme case of ad hoc description which becomes very complicated very quickly. I don't think this is useful, and I don't think we are any longer talking about Bell's Theorem. And I don't think the theory we arrive at could withstand the objective assault that it would be subjected to. As I said to begin with, we could just as easily postulate that God personally tricks us into witnessing the results by biasing Bell tests... and this is just as reasonable (or unreasonable) as any Superdeterministic theory.

You should see by now the difference between a mathematically well defined, deterministic law of motion at Plank scale and a fuzzy concept like a god. In the first case there is no bias, the law is no different for human observers or something like that. EPR correlations should appear as an emergent consequence of that unique law of motion.

 

[DrChinese]

The mistake in your line of reasoning is related to the scale you use to look at these experiments...Seen from a macroscopic point of view each "different" experimental setup is the quantum analogous of different galaxies in general relativity. We shouldn't expect a different law of gravity for each type of galaxy or for each type of massive object (stars, neutron stars, planets, gas clouds, etc.). Why do you think we should expect a different behavior at Plank level when the microscopic attributes of the object change?...The causal connection is "hiding" in the interactions between the particles contained in the source and detectors. The particle configuration in the detector (including whatever is supposed to change its orientation) produces a specific local field and this field determines the motion of the electron that later will emit the photons...

...Hand-waving which ignores the point. It is up to the super-deterministic theory - of which none is being offered by you or anyone else - to explain that these setups lead to the same QM predicted results as we actually see. That the mechanics is at the quantum level was acknowledged, and certainly I am not arguing that there is not a connection between different forces. However, current QFT does not support any kind of interaction such as what you speculate might exist. You cannot simply throw out ALL other theory without providing a replacement.

There are strict requirements for serious theory development, just ask anyone who is working on string theory. You have the tail wagging the dog: in trying to save local realism, you are throwing out everything else we know. It works the other way: you need a mechanism that preserves what we already know, but adds something new and useful.

 

[Count Iblis]

't Hooft did first start with some attempts to develop deterministic theories. He only started to mention "superdeterminism" later to defend these attemps against the criticism that these attempts are a priori doomed to fail because of Bell's theorem.

 

[DrChinese]

't Hooft did first start with some attempts to develop deterministic theories. He only started to mention "superdeterminism" later to defend these attemps against the criticism that these attempts are a priori doomed to fail because of Bell's theorem.

Yes, and I think these attempts ARE doomed a prioi because of Bell's Theorem. I realize that convoluted escape mechanisms are appealing to those who see local realism as something that SHOULD be fundamental. But here is the ultimate challenge for any true local realistic theory:

IF i) a particle has well-defined non-commuting observables, AND ii) they have these values independent of the act of observation, AND iii) these values have an element of reality as defined by EPR, THEN you should be able to come up with some sample table of the values that matches Malus' Law (i.e. the cos^2 relationship predicted by QM).

But that is not possible. You can't construct ANY sample set of values for a photon's polarization at settings of A=0, B=120 and C=240 degrees which yields close agreement with the relationship that:

Correlation(AB)=Correlation(BC)=Correlation(AC)=.25 (QM predicted value)

I mean, if you can't even do that by hand-picking the values, how are you going to convince anyone that there are such real values?

So why isn't super-determinism (quantum DNA) a valid escape mechanism? Because Bell's Theorem only gave us one escape mechanism other than the rejection of realism. That is rejection of locality. 't Hooft should show us a specific point in Bell's Theorem which opens things up for his ideas. I think he has failed on this score to date. (Of course, no harm in trying - that's what these discussions are all about.)

Now we know that non-locality is a valid "escape mechanism" because perhaps an observation at Alice affects the outcome at distant Bob. But that in turn requires that we have a hypothetical non-local mechanism to accomplish same. Bohmian Mechanics has been offered as such a solution, although there is no other physical evidence of non-local forces.

But I would honestly question to what extent BM answers the question of the "realism" of the underlying non-commuting properties when they can never - in principle - be revealed. At least, not using the idea that EPR envisioned (i.e. entanglement).

 

[LaserMind]

If we have two entangled particles sharing three states (say spin, position, momemtum), then those three could collapse in any combination with respect to each other.

 

[ueit]

...Hand-waving which ignores the point.

On the contrary, I think I've honestly answer to each objection you have raised. Remember, we are speaking here about classes of theories that might be possible, not about developed theories. This is the point of finding no-go theorems, to see what is possible in principle.

It is up to the super-deterministic theory - of which none is being offered by you or anyone else - to explain that these setups lead to the same QM predicted results as we actually see.

I agree that this should be the goal of everybody that works on such a theory.

That the mechanics is at the quantum level was acknowledged, and certainly I am not arguing that there is not a connection between different forces.

OK

However, current QFT does not support any kind of interaction such as what you speculate might exist.

I don't think that a full QFT computation of such a complex system is possible. Last time I've checked the most complex system that has been solved was a two-particle system (pion). A three particle one (neutron, proton) was already too hard. So, nobody knows what exactly a quantitative QFT treatment of an EPR experiment would reveal.

You cannot simply throw out ALL other theory without providing a replacement.

I didn't imply such a thing. On the contrary, I specified that any interpretation should give you back the schrodinger equation. The purpose is to find an explanation that makes sense for a statistical correct theory (QM), not to reject the later.

There are strict requirements for serious theory development, just ask anyone who is working on string theory. You have the tail wagging the dog: in trying to save local realism, you are throwing out everything else we know. It works the other way: you need a mechanism that preserves what we already know, but adds something new and useful.

Yes, this is my position, too. The question is what type of mechanism one should search for. I think that a superdeterministic one is a viable option.

 

[vanesch]

I don't think that a full QFT computation of such a complex system is possible. Last time I've checked the most complex system that has been solved was a two-particle system (pion). A three particle one (neutron, proton) was already too hard. So, nobody knows what exactly a quantitative QFT treatment of an EPR experiment would reveal.

What you seem to miss is that in no matter what quantum theory (or for that matter, bohmian mechanics or whatever), we *specify externally* what are the measurements we are going to do. The theory can give an answer no matter what external input we use as "measurement settings". You don't have to follow through any complicated calculation to *find out* what measurement one is going to do, you put it IN by hand - in fact, there is not even any sensible way in which one could calculate, from first principles, what measurement one would do! EVEN if you could follow up through all the calculations - which is impossible in quantum theory, as well as in classical theory, and probably in ANY theory, current or future - you would still have to specify EXTERNALLY what's the measurement that is going to be performed (the choices of the angles, or the system that will determine this choice, or whatever) - it would be part of the description of the setup which you can (have to) arbitrarily determine before you could even start your (hopeless) calculation.

In other words, a quantum mechanical "problem description" contains not only the "correct" (superdeterministically correct) measurement settings, but all other, counterfactual, superdeterministically impossible, settings, and nevertheless grinds out an answer.

It is because of this freedom (external freedom, that is, we can do the calculations for all non-superdeterministically possible settings, and not only for the few superdeterministically allowed settings) that it is not going to be possible to demonstrate any *equivalence* between a superdeterministic theory and a non-superdeterministic theory such as quantum theory in all its variants, such as BM, MWI, or whatever.

You see, it is as if in classical mechanics, you would come up with a "super-configurational" theory that states that the positions of the particles also determine their momentum in some hidden way, and that this explains entirely classical mechanics. Now, you are not going to be able to show any equivalence with classical mechanics, because in classical mechanics, you are FREE to pick any momentum you like with a given particle configuration. You can do the classical calculation for all the "impossible" momentum assignments too out of which the "super-configurational" theory only picks one or a few possible ones. You are never going to be able to show that picking these few are going to be equivalent to the workings of classical mechanics, as most of the classical mechanics "initial conditions" are impossible in the new theory.
The only way to show this, is to demonstrate that if you do the entire calculation for those few specific allowed initial conditions, you nevertheless end up each time with all possible observable results from classical mechanics, with well-chosen initial conditions.

 

[ueit]

?? If there is a long-range force that's going to do the thing, then it is not local, right ? The quantum force in BM is not local, Newtonian gravity is not local, electrostatics is not local. What is local is a local field propagation equation, like Maxwell's equations or Einstein's equations. If you allow for long-range forces, then you don't NEED superdeterminism, as Bell isn't supposed to hold in that case. No, the only thing that is allowed are local interactions. That's what makes superdeterminism so hard to handle: the correlations must arise through a whole chain of local interactions from a certain "common initial state" up to the actual manifestation of the correlations, through the precise tuning of the "choices" of measurement in agreement with the particular sets of particles that have been emitted.

Sure, I have used the term "force" instead of field. I agree with what you say.

Yes, but also with the measurement process!

Sure.

In fact, that wouldn't be ok. In order for superdeterminism to hold, it must also do it in *the most complicated EPR test possible*.

Some theories cannot be scaled up easily. Quantum chromodynamics is such an example. GR might be another example. This doesn't mean they are wrong.

That would be a start, but then you'd have to show that those molecules appear in exactly those orientations, each time, to measure the photons along the right axis, each time. And then you must show that WHATEVER I ADD, that this is not going to change this. *this* is, IMO, the impossible task of showing superdeterminism.

You have the "source" atom evolving in the field generated by the "detectors" and anything else you might add. When this field has a certain magnitude and a certain orientation the entangled photons are produced as a function of this particular magnitude and orientation. I don't see the reason why the required correlation could not appear in this way. Now, you may be right and this could be impossible but this should be mathematically proven (as a new no-go theorem for example).

Because it would be sufficient to find one single system that doesn't orient the "detecting molecules" in exactly the anticipated way, to undo the entire system. Now, I know your objection to that: something like "conservation of energy" is superficially in the same situation, and we don't have to follow up on all possible engines to show the first law of thermodynamics. But there's a difference. In things like conservation of energy, there is a clear physical parameter which is conserved by each interaction, and hence, also overall. I don't see how one could introduce something like "conservation of choice" that makes that *this* photon, no matter how, is going to be analysed only with *that* analyser angle. If ever such a thing existed, it would mean we would have a relatively simple "thermodynamics of (non)free will" in all generality.

Again I don't think this question can be settled without a rigorous mathematical treatment. I agree that it doesn't sound very intuitive but this is also true for every other possible explanation of EPR.

No, there's a big difference. In QM, or classical physics, we *don't have to* follow up through all the nitty gritty detail, because it doesn't involve the *essential effect*. If a photon is detected with a PM, well, that PM is going to generate a signal and all that, and this is going to be recorded etc... but we don't need the details here because they don't matter. They don't compose the essential effect we are observing (detecting a photon). So this can be abstracted away without any difficulty.

However, if the process that makes Joe choose angle th1 is the essential mechanism, this is different.

Detecting a photon is not the same thing as checking the QM formalism against a complex system. I could claim, for example that QM does not apply to a human brain and you couldn't prove me wrong. I wouldn't make such a claim because I find the extant experimentally verification of QM satisfactory. And those verifications are limited to very simple systems like small atoms or (with some approximations) molecular bonds or solids that show periodicity (crystals).

 

[vanesch]

You have the "source" atom evolving in the field generated by the "detectors" and anything else you might add. When this field has a certain magnitude and a certain orientation the entangled photons are produced as a function of this particular magnitude and orientation. I don't see the reason why the required correlation could not appear in this way. Now, you may be right and this could be impossible but this should be mathematically proven (as a new no-go theorem for example).

You won't find a no-go theorem because it is very well possible. What I'm claiming is that I don't see how one could ever *demonstrate* a superdeterministic theory to be superdeterministic, even if it were. I'm claiming that the only way to PROVE that a theory is superdeterministic is to follow through the complicated relationship between "thing that apparently makes the choice of the measurement" and the emitted pair of photons.
Because *anything* could be used to set up the measurement angles (and that "everything" might be outside of the lightcone of the emitting atom at the event of emission, so your "in the field of the detectors" won't hold: take as an example remote starlight from opposite directions which decides the detector angles: when the emitting atom is emitting the pair of photons, this starlight is still on its way and couldn't have reached (or anything else at c couldn't have reached yet) the emitting atom). Even if a theory were superdeterministic, you wouldn't be able to demonstrate it, as it would involve a complicated follow-up which is FAPP impossible.

Again I don't think this question can be settled without a rigorous mathematical treatment. I agree that it doesn't sound very intuitive but this is also true for every other possible explanation of EPR.

Well, my point is that it won't be doable to demonstrate it. Even if we have it (without knowing).

Detecting a photon is not the same thing as checking the QM formalism against a complex system. I could claim, for example that QM does not apply to a human brain and you couldn't prove me wrong. I wouldn't make such a claim because I find the extant experimentally verification of QM satisfactory. And those verifications are limited to very simple systems like small atoms or (with some approximations) molecular bonds or solids that show periodicity (crystals).

I know that I cannot prove the claim that QM does or doesn't apply to the human brain. But the point is, *it doesn't matter* for the results. You can put the Heisenberg cut just anywhere, and it will yield in the majority of cases, the right result. So QM results do not NEED a detailed follow-up through a complicated chain of events, once you've the essential part - and that's in part because we can accept externally given "free will" decisions. But a superdeterministic theory CANNOT do that: it wouldn't give self-consistent results if we "forced" it into free will decisions which are not compatible with its dynamics which is supposed to generate superdeterministic correlations. So in a superdeterministic theory we have no choice but to follow up through all the complicated chain of events up to the "determined experiment choice".

 

[talmans]

I'm a layman and haven't studied entanglement or read deeply about the subject so I apologize if this is a tired question. Couldn't entangled particles be evidence of other dimensions? There is no spooky action at a distance because the particles aren't entirely separated.

Do any other theories allow for this interpretation?

 

[LaserMind]

I'm a layman and haven't studied entanglement or read deeply about the subject so I apologize if this is a tired question. Couldn't entangled particles be evidence of other dimensions? There is no spooky action at a distance because the particles aren't entirely separated.

Do any other theories allow for this interpretation?

I tend to 'think' along those lines to get answers for myself, although I have not seen an extra dimension to account for entanglement. A new dimension could be a little mathematical device we use to get answers with maybe some physical truth behind. Indeed, in QM two particles have 6 dimensions in the complex vector space already. So that's a start, but not quite what you mean.

It 'appears' that entangled particles behave, in certain ways, as if they are still very close to each other. As if distance and time do not apply to them. I rationalize myself with another dimension at work, rather than MWI, Superdeterminism, and am always reading any plausible offering with interest.

 

[Dragonfall]

What can we say about entangled pairs and their gravitational attraction? I know there's no quantum gravity yet, but take a guess.

 

[sudhirking]

what do u mean there is no quantumn gravity yet,,,,,,,
if you think about it, gravity itself is not by the mass of an objest other tham the curvature of quarks. so techinacally speaking, the only curvature there is iin quarks.

 

[jtbell]

what do u mean there is no quantumn gravity yet

There is no generally accepted theory of quantum gravity yet. It's a major area of theoretical research.

 

[sudhirking]

Becuase of what i said above, i believe that these quarks is undefined by our univesr because the smallest thing in this universe does not exist in our universe as the smallest thing would have a negative mass in awhich it could not be held by our universe but be in the antiuniverse. And since gravity only applies with quarks, our universe is the gravity of th e anti-universe. as for the entanglements, they could be fluctuations in the boundries between anti-universe and the regular universe

 

[sudhirking]

well that idea above uses my theory of everything ( WHICH I REALLY AM STILL EDITING BUT I WANT TO PUBLISH)
however i am self taught and i am only a freshman so i probably don't understand a lot of science. BUT I am so postitve my theory of everything is right, as it is everything it is supposed to be and fits wiht all current ideas and even applies quantum mechanincs to realativty and explains the inflamation theory.

But for one thing.: I AM SURE THAT GRAVITY ONLY WORKS WITH THE QUARKS AND THEREFORE GRAVITY IS ALWAYS QUANTUM!

PS what is a PF Mentor

 

[peter0302]

But for one thing.: I AM SURE THAT GRAVITY ONLY WORKS WITH THE QUARKS AND THEREFORE GRAVITY IS ALWAYS QUANTUM!

Why do electrons fall to the ground then?