Does entanglement violate special relativity?

[Isaac_Newton]

I don't see why the age difference in the particles should prevent them being correlated. why should there be any change in entanglement?

Its up to you to say why entangled particles of different ages (brought about by a high speed relativity trip) remain in the exactly the same correlation even though one is two days older than the other.
What is it about entanglement that did not change?

 

[Demystifier]

The "theorem" is nothing but a tautology (if the particles in the experimenter's brain are not described by a deterministic theory it follows that all other particles share this property). Given that there is no evidence that a brain consists of a different type of particles than the rest of the world there is nothing more to prove, no reason to appeal to EPR or even to QM. The "proof" follows from logic alone.

I almost agree:
https://www.physicsforums.com/showthread.php?t=144925

In addition, I think that free will implies incompleteness of QM:
https://www.physicsforums.com/showthread.php?t=174544

 

[DrChinese]

Its up to you to say why entangled particles of different ages (brought about by a high speed relativity trip) remain in the exactly the same correlation even though one is two days older than the other.
What is it about entanglement that did not change?

Well, the obvious point is: if Alice is observed after .001 second, and Bob is observed at any time thereafter (so that Bob is older), the correlation remains (as predicted by QM). So the only issue relates to the effect, if any, of having Bob interact with a gravitational field. Does that cause decoherence and therefore end entanglement? As of today, this is entirely an open question and there is no evidence either way. Feel free to speculate...

 

[Ilja]

I do believe that the BM/dBB school needs to quit asserting that there is *no* possibility of a testible difference between QM and BM. If there isn't, what is the value of BM as a theory? It simply becomes an ad hoc explanation for existing facts. The sQM school is taking the possibility of verifying or rejecting BM seriously; and I would like to see more of that attitude.

First, that is not a question about asserting - or there is equivalence, or there is not. Once there is a theorem about equivalence in quantum equilibrium, there is no possibility, if we are trapped in equilibrium. Very sorry, but there is no choice.

If there isn't, the value of BM as an empirical theory is the same as of QM. Once you do not seem to propose the throw away QM, I see no reason to throw away BM.

There are important metaphysical differences, in particular there is no measurement problem, no nonunitary evolution of the wave function, and, very important, the whole measurement theory postulated in QM can be derived from something much more simple. Given the simplicity of this derivation, BM should be preferred by the usual standards of preference for the simpler theory.

My personal interest is to understand how the universe works. It is not to find some theory which differs in some prediction from the standard one - if it happens that such a modification allows for a much simpler understanding of our universe - fine, I will embrace it. (For example, my theory of gravity contains some additional terms, see ilja-schmelzer.de/glet/, but there was a good reason for introducing them.) But I see absolutely no reason to change successful theories.

 

[Demystifier]

There are important metaphysical differences, in particular there is no measurement problem, no nonunitary evolution of the wave function, and, very important, the whole measurement theory postulated in QM can be derived from something much more simple. Given the simplicity of this derivation, BM should be preferred by the usual standards of preference for the simpler theory.

My personal interest is to understand how the universe works. It is not to find some theory which differs in some prediction from the standard one - if it happens that such a modification allows for a much simpler understanding of our universe - fine, I will embrace it.

I cannot agree more.

 

[debra]

I cannot agree more.

I cannot agree less! We are discussing "Does entanglement violate special relativity" not pushing Bohm - you don't seem interested.

 

[Demystifier]

I cannot agree less! We are discussing "Does entanglement violate special relativity" not pushing Bohm - you don't seem interested.

That's fair. However, I think that the question "Does entanglement violate special relativity?" cannot be answered irrespective of the interpretation one works with. Thus, it is interesting to see how different interpretation answer this question. One of the interpretations is the Bohmian one, and that's how we arrived at it.

 

[Ilja]

I cannot agree less! We are discussing "Does entanglement violate special relativity" not pushing Bohm - you don't seem interested.

The questions are closely related. First, it seems unjustified to take some part (entanglement) out of quantum theory and to ask separately if it "violates relativity". It is quantum theory as a whole which violates (or not) relativity.

But this question cannot be discussed without specifying particular interpretations. For relativity, you have to distinguish two interpretations: One where relativistic symmetry is about observables, one where it is about reality. And for quantum theory, you need such differentiation as well.

In the pilot wave interpretation special relativity (its fundamental interpretation) is violated, its observable variant not. In general, the observable variant of relativity is not violated by quantum theories. There are non-realistic interpretations of quantum theory, and for these interpretations the fundamental, realistic interpretation of relativity simply makes no sense. For realistic interpretations, realistic relativity is violated.

The exception is the many words interpretation (no typo), which claims to be realistic and claims to be in agreement with relativity. All this, in the modern variants, without formulas defining their basic objects or probabilities or whatever else you would like to compute.

 

[Dmitry67]

It is not SR but CAUSALITY which is violated
But causality is somehow volated in the closed timelike loops, so GR also violates causality.

 

[Ilja]

It is not SR but CAUSALITY which is violated
But causality is somehow volated in the closed timelike loops, so GR also violates causality.

Sorry, in the quantum context there is no violation of causality. Again, pilot wave interpretation is the explicit counterexample. One with formulas and theorems.

Handwaving I leave to MWI.

 

[Dmitry67]

I mean the topic subject is incorrect.
When people say 'entanglement violates SR' they mean FTL -> causality problems.
But in fact (I agree with you) there is no such violation, even the entanglement is discussed in that context over and over again

P.S.
I understand that you hate MWI, but just curious, what interpretation do you like?

 

[debra]

Lets set a simple scenario:
Lets first of all make an empty 3D space about the size of the Universe. Into which we will place two particles. We want to study SR and entanglement using real physical classical objects.
Is that OK or is it illogical in some way?

 

[nikman]

Lets set a simple scenario:
Lets first of all make an empty 3D space about the size of the Universe. Into which we will place two particles. We want to study SR and entanglement using real physical classical objects.
Is that OK or is it illogical in some way?

Someone like (say) Max Tegmark might say it's not coherent. He maintains that physical existence began with (1) a specific, defined set of initial conditions and (2) something like the Schrödinger equation to determine future evolution (within the probabilities associated with both the SE and classical complexity).

So, a thought-experiment of your kind posits a kind of scale separation and may be a simulation fallacy. It's a computationalist abstraction. Can you really separate those two particles and their behavior from the complete history of the universe? And how would you incorporate that into the model?

 

[nikman]

Also, maybe a more practical consideration: GR takes the Universe to be in part a function of the total matter-energy it contains. Could you have "an empty 3D space about the size of the Universe" if the Universe is only two particles?

So you scale down. Make it a Universe of a size appropriate to a Universe of only two particles. Would that be equivalent?

 

[DrChinese]

He maintains that physical existence began with (1) a specific, defined set of initial conditions and (2) something like the Schrödinger equation to determine future evolution...

...Can you really separate those two particles and their behavior from the complete history of the universe?

Max Tegmark is a Many Worlder, I think. He has written articles on parallel universes. Addressing your comments:

1. From a factual viewpoint, this does not appear to be accurate based on what we currently know. There are parts of the universe that have never been in causal contact with us. And the part that has is constantly changing - i.e. is not static.

2. Further, there is a powerful virtual particle field that we are immersed in. Clearly, these particles are affecting us. Are virtual particles evolving according to these same deterministic laws?

I don't think you are saying that you are advocating a deterministic viewpoint, but I just wanted to get clarification.

 

[nikman]

Max Tegmark is a Many Worlder, I think. He has written articles on parallel universes. Addressing your comments:

From a factual viewpoint, this does not appear to be accurate based on what we currently know. ... There are parts of the universe that have never been in causal contact with us. ... Are virtual particles evolving according to these same deterministic laws?

I don't think you are saying that you are advocating a deterministic viewpoint, but I just wanted to get clarification.

He's a "many-minder" along with Dieter Zeh. Same difference as far as I can tell, and then some.

He stated the initial conditions bit explicitly, and probably not for the first time, in his 1996 paper "DOES THE UNIVERSE IN FACT CONTAIN ALMOST NO INFORMATION?" which he still links to from his website. No alteration, no repudiation. We can assume he at least doesn't consider it outmoded.

Causal contact isn't the issue, apparently. It's all about universal entanglement. It seems deeply deterministic (in the sense that the Schrödinger equation is deterministic) but not I think as uncompromisingly deterministic as 't Hooft's determinism. The randomness component seems to be genuinely quantum stochastic, not some hidden pseudo-randomness originating down at the Planck length amid the foam.

Tegmark's pal Dieter Zeh's analogy (he uses it as a metaphor for teleportation) is the Grimm's tale "The Hare and the Hedgehog". Mrs. Hedgehog at the top of the row, Mr. Hedgehog at the bottom, unpacking their pre-arranged plot. No causal contact between them, pure kinematics, just the hare running back and forth until he drops dead. I guess that's the universe, unpacking itself per initial conditions evolved through an algorithm.

There's a Deutschian component there too, the Universe as Computer, common to almost all many-whatevers. I've never understood why you'd need all those universe-worlds to store information. If you want to go total informationalist I like Hans C. von Baeyer's peeled-grape uncollapsed qubit. It's all in there, right here in this unparalleled world-universe, all the goodies anyone could ever want, if we could only decipher it. But we can't. "All we get is one lousy [classical] bit," as von Baeyer says.

No, I don't buy the Tegmarkian universe. But would I stake my life on its being bogus? No.

So, re: debra's idea: I do believe in the possibility of larger domains of entanglement beyond simply that of any two or three or however many defined correlated particles. Entanglements within entanglements, correlation sets within correlation sets. So the actions of any entangled pair wouldn't necessarily just be reflective of their own immediate correlations. But maybe you'd only discover that if you were actually able to isolate the particles, as in a hypothetical two-particle universe. Also it seems like a two-particle universe wouldn't be equivalent as a relativistic entity to the one we know. So at the moment I'm inclined to think the idea may have problems.

 

[Dmitry67]

There's a Deutschian component there too, the Universe as Computer, common to almost all many-whatevers. I've never understood why you'd need all those universe-worlds to store information. If you want to go total informationalist I like Hans C. von Baeyer's peeled-grape uncollapsed qubit. It's all in there, right here in this unparalleled world-universe, all the goodies anyone could ever want, if we could only decipher it. But we can't. "All we get is one lousy [classical] bit," as von Baeyer says.

Max Tegmark denies it, he says that we are NOT emulated and no computer is need

 

[nikman]

Max Tegmark denies it, he says that we are NOT emulated and no computer is need

Okay. I know he says that every true mathematical statement gets physically realized in some universe within the multiverse, so there must be at least one universe in which Turing Machines can't exist due to conflicts with other conceivable mathematics. He says that, more or less anyway, in one of his papers.

I tend to conflate him with Nick Bostrom sometimes. Their relationship goes all the way back to Sweden and they've written at least one paper together. Bostrom is notorious for pushing the idea that we may well be living in a computer simulation. Any material you can cite where Tegmark specifically disputes that approach would be appreciated.