Does entanglement violate special relativity?

[ueit]

This is inaccurate, determinism does NOT imply superdeterminism. Even if my decisions are predetermined, that does not mean that the Bell Inequality will be violated by my choices of measurement settings - which is the premise of superdeterminism.

I don't think Bell Inequality is a premise of superdeterminism. At least in my understanding, superdeterminism is determinism applied globally, to the entire system of interest. Saying that a part of a system evolves deterministically while another is allowed free choices is logically absurd. IMHO, the so-called weirdness of QM has its roots in this absurdity.

Your superdeterminism is supposed to explain something, and it doesn't. Every particle would need to have all the details of all other particles contained locally to work. We have previously discussed this point in other threads, and concluded that superdeterminism has baggage. Further debate of superdeterminism here would be off-topic.

You are the one who started this debate on Bell Inequality here. To stay on topic I will not continue it further. My point was strictly related to the issue of non-locality in the context of a deterministic theory, not about how Occam-friendly this or that interpretation is. anyway, I didn't agreed to your conclusion "superdeterminism has baggage", that's your opinion only.

 

[Demystifier]

Although its a negative its as strange as correlation 'exchanges' & probably for the same reason. - For me its about information in information space, so I see no problem, but for the rest of you... boy, do you have problems!

Does it mean that you accept the idea that nothing really exists except information?

 

[Demystifier]

At least in my understanding, superdeterminism is determinism applied globally, to the entire system of interest. Saying that a part of a system evolves deterministically while another is allowed free choices is logically absurd. IMHO, the so-called weirdness of QM has its roots in this absurdity.

I fully agree! Indeed, there is a theorem that confirms this (in QM):
http://xxx.lanl.gov/abs/quant-ph/0604079
http://xxx.lanl.gov/abs/0807.3286

 

[DrChinese]

I fully agree! Indeed, there is a theorem that confirms this (in QM):
http://xxx.lanl.gov/abs/quant-ph/0604079

That seems a weird reference for you to agree with... they claim it rules out all deterministic theories (including Bohmian/dBB type) other than superdeterministic ones. Nice paper, by the way, covers a lot of interesting ground.

 

[Dmitry67]

As far as I know MWI starts with a wavefunction. That wavefunction evolves deterministicaly in accordance with Schroedinger's equation. You should explain what do you mean by "empty space" and "fluctuations" in this context.

Based on the current cosmological model, we had an inflation era. During that time space was empty (sort of vacuum). Then vacuum started to decay giving life to 'particles'

What is important is that during that time the first fluctuations appear... is some places there were MORE particles then in another places. For that reason we have galaxies somewhere while other space is almost empty.

So how could a state of universe where all points of space were in the same state (empty, vacuum) could evolve into another state where in SOME places there was MORE matter then in another ones?

To allow such symmetry breaking theory must be non-deterministic (CI for example) or multi-history (MWI allows to break symmetry deterministically, breakig it differently in different worlds).

Deterministic single-history theory can not, in principle, convert a state with low entropy (like empty space) into something complex, like what we observe.

 

[Isaac_Newton]

Special relativity (SEE THREAD TITLE)
is an information rule that must apply
for a field model of the universe to work.
Otherwise cause and effect would mess up.
But no particles are separated at all.

This is more like what it 'looks like':

10101011110010101001001110010010001
11101001001010100100010101010101010
10101010010001000111110110100001111
10101011110010101001001110010010001
11101001001010100100010101010101010
10101010010001000111110110100001111
10101011110010101001001110010010001
11101001001010100100010101010101010
10101010010001000111110110100001111
10101011110010101001001110010010001
11101001001010100100010101010101010
10101010010001000111110110100001111
10101010010001000111110110100001111
10101011110010101001001110010010001
11101001001010100100010101010101010
10101010010001000111110110100001111
10101011110010101001001110010010001

The above is information space (in bits not
Qubits which I cannot show) which has
both our entangled particles in it (We also
live in there, 3 D space is created in it
- as Newton said - the universe was created with numbers,
- 3 D space is a total illusion, but a good one).

 

[QuantumBend]

Special relativity (SEE THREAD TITLE)
is an information rule that must apply
for a field model of the universe to work.
Otherwise cause and effect would mess up.
But no particles are separated at all.

This is more like what it 'looks like':

10101011110010101001001110010010001
11101001001010100100010101010101010
10101010010001000111110110100001111
10101011110010101001001110010010001
11101001001010100100010101010101010
10101010010001000111110110100001111
10101011110010101001001110010010001
11101001001010100100010101010101010
10101010010001000111110110100001111
10101011110010101001001110010010001
11101001001010100100010101010101010
10101010010001000111110110100001111
10101010010001000111110110100001111
10101011110010101001001110010010001
11101001001010100100010101010101010
10101010010001000111110110100001111
10101011110010101001001110010010001

The above is information space (in bits not
Qubits which I cannot show) which has
both our entangled particles in it (We also
live in there, 3 D space is created in it
- as Newton said - the universe was created with numbers,
- 3 D space is a total illusion, but a good one).

This computers not physics. Read Quantum Field Theory and Quanum Mechanis.

 

[Ilja]

A fundamental theory that is deterministic is necessary superdeterministic. A deterministic theory at a fundamental level allowing "independent decisions of experimenters" is logically contradictory, therefore it makes no sense to seriously speak about it.

No. A deterministic theory allows to explain the observables in terms of some sufficiently small subsets of the state of the universe, so that one can introduce a notion of causality as well as of independence. There is no contradiction at all. Simply in some deterministic theories some events do not depend on the whole universe one minute ago, but only on some small part of the universe one minute ago.

 

[Demystifier]

That seems a weird reference for you to agree with... they claim it rules out all deterministic theories (including Bohmian/dBB type) other than superdeterministic ones. Nice paper, by the way, covers a lot of interesting ground.

It does not rule out Bohmian/dBB type theories because such theories are naturally interpreted as superdeterministic (provided that the notion of "superdeterministic" is understood appropriately).

 

[Demystifier]

Deterministic single-history theory can not, in principle, convert a state with low entropy (like empty space) into something complex, like what we observe.

Man, what are you talking about?
An obvious counter-example to your claim is classical mechanics of many degrees of freedom, where entropy is understood as the coarsegraining entropy.

 

[Dmitry67]

Sorry, I meant some specific examples of entropy increase.

I should say
'Deterministic single-history theory can not, in principle, break a symmetry, for example, convert an empty space (empty everywhere) into space where somehwere there are stras, planets, while in the other parts space is void'

 

[lalbatros]

Any way to FTL with entangled system?

I believe the answer is no. But I have some doubts.

Assume we create every microsecond an entangled spin pair, for a total of 1000000 pairs.
Assume we will measure the entangled pairs when they are separated by 1 lightyear!
Assume the measuring device on side A will measure 0.1 microseconds before the measuring device on the other side B.
Assume the spin orientation on side A can be chosen freely for each individual measurement.

I have the intuiton that it would be possible to sent a few bits of information (say one bit) from A to B at a Faster Than Light speed. But this transfer would not be totally reliable. The reliability would increase with the number of pairs analysed as well as with the ingeniosity of the experimenter.

Am I dreaming?

 

[alxm]

I have the intuiton that it would be possible to sent a few bits of information (say one bit) from A to B at a Faster Than Light speed.

How did your particles get separated at FTL speed?
Or were they separated at the start? If they were, how did they become entangled? That requires them to interact with each other. How did they interact at FTL speed?

 

[DrChinese]

It does not rule out Bohmian/dBB type theories because such theories are naturally interpreted as superdeterministic (provided that the notion of "superdeterministic" is understood appropriately).

In superdeterminism, the choice of an experimenter's measurement setting is controlled by initial conditions in just such a way as to allow Bell's Inequality to be violated. In strict determinism, the experimenter's choice of measurement setting is not "free", but Bell's Inequality is not violated as a postulate of the theory. Instead, there is some other mechanism (in your case non-locality) which is responsible.

 

[lalbatros]

How did your particles get separated at FTL speed?
Or were they separated at the start? If they were, how did they become entangled? That requires them to interact with each other. How did they interact at FTL speed?

Just as in the Alain Aspect experiment, just on a longer scale for the story.
Two entangled photons traveling in opposite ways, and the experimenter waiting long enough.

 

[alxm]

Just as in the Alain Aspect experiment, just on a longer scale for the story.
Two entangled photons traveling in opposite ways, and the experimenter waiting long enough.

And how does this transmit information FTL?

 

[Demystifier]

In superdeterminism, the choice of an experimenter's measurement setting is controlled by initial conditions in just such a way as to allow Bell's Inequality to be violated. In strict determinism, the experimenter's choice of measurement setting is not "free", but Bell's Inequality is not violated as a postulate of the theory. Instead, there is some other mechanism (in your case non-locality) which is responsible.

I think I still don't understand the difference between superdeterminism and strict determinism. Can you explain the GENERAL difference between these two concepts, without referring to QM and nonlocality?

Anyway, in Bohmian mechanics both the initial conditions and nonlocal forces are responsible for the violation of Bell inequalities as predicted by standard QM. The initial conditions are important because the initial particle positions in the statistical ensemble must be distributed according to |psi|^2, which corresponds to the so-called quantum equilibrium hypothesis. If this initial condition has not been satisfied, then the violation of Bell inequalities could be even stronger than predicted by standard QM (see the papers of Valentini).

 

[DrChinese]

I think I still don't understand the difference between superdeterminism and strict determinism. Can you explain the GENERAL difference between these two concepts, without referring to QM and nonlocality?

Anyway, in Bohmian mechanics both the initial conditions and nonlocal forces are responsible for the violation of Bell inequalities as predicted by standard QM. The initial conditions are important because the initial particle positions in the statistical ensemble must be distributed according to |psi|^2, which corresponds to the so-called quantum equilibrium hypothesis. If this initial condition has not been satisfied, then the violation of Bell inequalities could be even stronger than predicted by standard QM (see the papers of Valentini).

In ordinary determinism: [initial conditions] + [physical laws] -> [observed results]. However, there is no reason that this would ever lead to violation of a Bell Inequality. Why would it? There would be no reason that a measurement setting at Alice would be somehow correlated with a result at Bob - at least certainly no more likely than a result involving unentangled particles elsewhere (let's say Chris).

The only purpose of superdeterminism (rather than determinism) is to provide a way to have Bell's Inequality violated in a local realistic manner. This has been postulated by a few authors (such as t' Hooft). From the Wikipedia article on Bell loopholes:

Superdeterminism

"Even if all experimental loopholes are closed, there is still a theoretical loophole that may allow the construction of a local realist theory that agrees with experiment. Bell's Theorem assumes that the polarizer settings can be chosen independently of any local hidden variable that determines the detection probabilities. But if both the polarizer settings and the experimental outcome are determined by a variable in their common past, the observed detection rates could be produced without information traveling faster than light (Bell, 1987a). Bell has referred to this possibility as "superdeterminism" (Bell, 1985)."

There is no other reason for superdeterminism to exist OTHER than to explain Bell's Theorem or any other portion of physics you disagree with for which there is physical proof of the side opposite to your view. There is, by definition, no possibility of disproof of this view. And further, there is no possibility - by definition - that it could ever lead to any advance in science. That is because it is strictly an AD HOC theory. It should be discussed in philosophical or religious forums rather than those devoted to physics.

 

[Demystifier]

Thank you for the clarifications, Dr. Chinese.
Anyway, I still claim that the free-will theorem, which in its refined version essentially says:
"If experimenters have free will than observed particles also have free will"
does not rule out BM, simply because in BM experimenters do not have free will.
Do you still disagree?

 

[Ilja]

That seems a weird reference for you to agree with... they claim it rules out all deterministic theories (including Bohmian/dBB type) other than superdeterministic ones. Nice paper, by the way, covers a lot of interesting ground.

It is irrelevant for dBB. They postulate some maximal speed of information transfer, which is violated on the hidden variable level in dBB.

 

[ueit]

I fully agree! Indeed, there is a theorem that confirms this (in QM):
http://xxx.lanl.gov/abs/quant-ph/0604079
http://xxx.lanl.gov/abs/0807.3286

I think that this "free-will theorem" is a good example of how untenable the position against the existence of hidden variable theories has become.

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.

 

[lalbatros]

alxm,

And how does this transmit information FTL?

I don't know. I just tried to imagine some attempt. Below is a naïve idea.

I also wonder if there is a general proof that FTL is impossible by entanglement.
On the simplest communication protocol, this is obvious.
Probably this can be proved also for any sophisticated protocol and FTL would be as illusory as free energy.

Naïve idea
Let's assume side A wants to send one bit to side B.
Creating one unique entangled pair as carrying media will never allow FTL.
Any action on side A, like orientation of a polarizer (polarisation), will imply a statistical "response" on side B.
But there is no way to transmit information since the noise is maximal.

It is then natural to try doing something using many well separated entangled pairs.
Naïvely speaking, the number or repetition could improve the statistics or reduce the noise.
There are at least two (desparate) ways to try FTL then.

1) One way "communication". Side A sends a pattern of polarisations. Surely this is hopeless because the probabilities are independent in each "broadcast" from A.

2) Two way "communication". Side A and B will alternatively be emitter or receiver and adjust their polarization based on their observations. The goal will be to beat FTL from A to B. Would it be possible when B and A chose their new polarization based on their previous observations?

 

[DrChinese]

Thank you for the clarifications, Dr. Chinese.
Anyway, I still claim that the free-will theorem, which in its refined version essentially says:
"If experimenters have free will than observed particles also have free will"
does not rule out BM, simply because in BM experimenters do not have free will.
Do you still disagree?

I definitely believe an experimenter has free will to choose a measurement setting, for all intents and purposes. I realize that at some level, there could be complete determinism but that doesn't change my view as a good and useful hypothesis.

There have been a lot of papers in the past 10 years that purport to rule out BM; or alternately prove the universe is non-local; or prove contextuality; or prove MWI; etc. I like the ambition and direction of some of these papers. But no, I do not believe that BM/dBB type theories are ruled out yet.

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.

But all this is just my opinion.

 

[DrChinese]

I think that this "free-will theorem" is a good example of how untenable the position against the existence of hidden variable theories has become.

I think this is an exaggerated statement. The no-go work on hidden variables is quite extensive, although it is not yet what I would call persuasive. On the other hand, no amount of experimental effort has been able to uncover even a hint of a hidden variable anywhere (of course to a Bohmian, the hidden variables are literally everywhere). That is strongly suggestive, but still not conclusive. So I think it would be manifestly unfair to characterize a single approach (such as Conway & Kochen) as representative of the entire interpretation.

 

[nfelddav]

alxm,
I don't know. I just tried to imagine some attempt. Below is a naïve idea.

A lovely attempt, but not likely to get anywhere... on the positive side, if it did, you'd probably get a Nobel prize.
But yes, there is a theorem that says you can't use entanglement to send information: there is no way to learn anything about the polarization of the measurement.
http://en.wikipedia.org/wiki/No_communication_theorem

 

[Isaac_Newton]

If one entangled particle goes on a high speed journey and is then younger by 2 days than its entangled partner they still maintain perfectly correlated states. Although the answer is easy for me, why do you think that is? (more universes?, more crafty pilot waves?, backwards in time fairies?, superdeterminism knew it would happen? a new cat theory?)

 

[nfelddav]

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

 

[DrChinese]

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

There is in fact an interesting nuance on this particular item. No actual test - that I am aware of, at least - has been done to confirm what we assume the result will be (which is continued correlation). Now why would this matter?

If gravity is a quantum force - an open question in physics - then any particle which is "younger" must have been accelerated or otherwise been subject to a very strong gravitational field (assuming I haven't got younger and older reversed). It therefore interacted with the gravitational field by absorbing and/or emitting gravitons. Presumably, that implies the possibility of a measurement involving the associated graviton(s). Would that affect the spin of the entangled particle? If it did, it would end the correlation with the entangled twin. If it didn't, the implication would be that gravity is not a quantum force.

From Sean Carroll's blog at Discover magazine:

"Brad DeLong, in re Quantum Hyperion, wonders whether photons are really responsible for the decoherence of Saturn’s moon:

'But gravity works–presumably, at some level–by massive objects constantly bombarding each other with gravitons, so we are also averaging over all the possible states of gravitons that we are not keeping track of, aren’t we? That should cause decoherence too, shouldn’t it?'

"This is an annoyingly good question. In fact, I’m probably not giving anything away if I reveal that my esteemed co-blogger Daniel and I once tried to figure out whether or not dark matter, if it truly interacts with ordinary matter only through gravity, would be in a coherent quantum state..."

 

[nfelddav]

Ah, very interesting...
Is it necessary that if it is a quantum interaction it will impact the spin?

 

[DrChinese]

Ah, very interesting...
Is it necessary that if it is a quantum interaction it will impact the spin?

Spin, I would think so, though I have no idea how that would work. Else momentum, frequency, etc.