Is action at a distance possible as envisaged by the EPR Paradox.

[unusualname]

Found one multiqubit (four-qubit) entangled experiment by Zeilinger et al. that cannot be described by local realism:

Over the last few decades I think local realism has clearly been shown to be untenable, and not even desirable ( what an uninteresting world it would be : ) )

I'm puzzled why there has been resistance, since we all possesses one thing that can't be modeled by local realist physics, our consciousness

I don't think my suggestions are even that adventurous, I mean, just asking for an extra dimension or two to bypass SR restrictions on FTL signalling is hardly less bizarre than the Copenhagen Interpretation, many-worlds or assuming instantaneous multiple correlations by magic.

You can ignore my speculations about consciousness and entanglement, but I think it's a good bet that the two are related, and I must again emphasise that a really simple process (evolution) created conscious beings.

 

[DrChinese]

Over the last few decades I think local realism has clearly been shown to be untenable, and not even desirable ( what an uninteresting world it would be : ) )

I'm puzzled why there has been resistance, since we all possesses one thing that can't be modeled by local realist physics, our consciousness.

So true! While some would like to return to local realism, it seems to me that the exciting things to ponder are in the other direction entirely. There could be some weird dimensions which exist in supersets of existing theory. Perhaps quantum non-locality is local in those dimensions. Or maybe there are strange beings there. (I mean: stranger than the strange beings here.)

 

[DevilsAvocado]

... (I mean: stranger than the strange beings here.)

Please forgive me! But I can’t help it! Moooooaaahhhhaaaa LOL!

 

[DevilsAvocado]

... or assuming instantaneous multiple correlations by magic.

I guess this will qualify me for the "severe strangeness classification" , but I can’t get this out of my head. I assume you are proposing a finite limited upper "speed" of the quantum non-local connection, right?

What 'mechanism' would handle the 'negotiation' between entangled particles, since there is only one particle (or 'end' of the entangled WF) who can 'settle/decide' the correlated outcome?

I know there are interpretations like RBW or MWI that makes this an non-issue, but these interpretations brings other 'stuff' that are more complex than this 'entangled negotiation' – and I always been a big fan of Occam's razor.

Any thoughts?

 

[DevilsAvocado]

But, any two are simultaneous in SOME frame and their temporal order switches in other frames, so how do you argue for an unambiguous causal ordering without resorting to a preferred frame?

How do we handle this view in respect of my question above? (i.e. the 'negotiation')

 

[my_wan]

So true! While some would like to return to local realism, it seems to me that the exciting things to ponder are in the other direction entirely. There could be some weird dimensions which exist in supersets of existing theory. Perhaps quantum non-locality is local in those dimensions. Or maybe there are strange beings there. (I mean: stranger than the strange beings here.)

Here is a paper that shows a violation of Bell's inequalities in classical statistics, among other things.

Abstract: http://arxiv.org/abs/0906.4919"

http://arxiv.org/abs/0906.4919]Quantum[/PLAIN] mechanics can emerge from classical statistics. A typical quantum system describes an isolated subsystem of a classical statistical ensemble with infinitely many classical states. The state of this subsystem can be characterized by only a few probabilistic observables. Their expectation values define a density matrix if they obey a "purity constraint". Then all the usual laws of quantum mechanics follow, including Heisenberg's uncertainty relation, entanglement and a violation of Bell's inequalities. No concepts beyond classical statistics are needed for quantum physics - the differences are only apparent and result from the particularities of those classical statistical systems which admit a quantum mechanical description. Born's rule for quantum mechanical probabilities follows from the probability concept for a classical statistical ensemble. In particular, we show how the non-commuting properties of quantum operators are associated to the use of conditional probabilities within the classical system, and how a unitary time evolution reflects the isolation of the subsystem. As an illustration, we discuss a classical statistical implementation of a quantum computer.

Section VIII covers Bell's inequalities. I can't honestly disparage considerations that local realism may in fact be a dead horse. What I can disparage is the claim that it is certainly so. It's not entirely honest on either side of the fence.

 

[DevilsAvocado]

... local realism may in fact be a dead horse. What I can disparage is the claim that it is certainly so. It's not entirely honest on either side of the fence.

I agree, and to be real honest we must also consider that fact that local realism may be a stone dead parrot... with the Norwegian Blue plumage...

Sorry, just a really bad joke. I agree in what you are saying – "It ain't over 'til the fat lady sings."

 

[my_wan]

I agree, and to be real honest we must also consider that fact that local realism may be a stone dead parrot... with the Norwegian Blue plumage...

Sorry, just a really bad joke. I agree in what you are saying – "It ain't over 'til the fat lady sings."

Actually I thought it was a pretty good Monty joke. [PLAIN]https://www.physicsforums.com/images/smilies/smile.gif

Given the weakness of the opposing arguments here, it appeared to me that many would get a false impression of excessive certainty of a particular view. I felt that needed corrected, as the actual physics involved don't presently allow a significant degree of certainty. Ironic [PLAIN]https://www.physicsforums.com/images/smilies/laughing.gif

 

[Galap]

But... even if we cannot use entanglement to send usable information FTL, the particles must clearly be 'communicating' in some way to present the opposite random property, right? And Bell showed there are no local hidden variables involved... or did I miss something?

MWI is the only 'way out' of this is, as I understand...?

The particles do not need to communicate. One explanation is that they are two aspects of the same thing that aren't in the same place. We have pretty much determined that space and time aren't fundamentals. They are more emergent properties of the universe. Why is it so surprising then that not all phenomena work that way. Something can be in two places at once. In this case, it's the wavefunction. No communication, just evidence that GR isn't a complete theory.

 

[unusualname]

The particles do not need to communicate. One explanation is that they are two aspects of the same thing that aren't in the same place. We have pretty much determined that space and time aren't fundamentals. They are more emergent properties of the universe. Why is it so surprising then that not all phenomena work that way. Something can be in two places at once. In this case, it's the wavefunction. No communication, just evidence that GR isn't a complete theory.

The problem with that argument is that it's a struggle to explain multiparticle entanglement in quantum computers (and perhaps the conscious brain), since all the particles would have to occupy the same "thing" (or have some component of their positions in multidimensional space fixed) undisturbed for long periods of time.

I think it's easier to imagine that signalling between the particles occurs in some non-classical space.

DrChinese posted a link to a recent experiment which established entanglement in photons from different sources ( http://arxiv.org/abs/1005.1426 ) , and several similar results have been published. These type of results make it difficult for me to see how entanglement can be due to particles being aspects of the same "thing" (or having the same component in multidimensional space)

But it's true that we can't rule it out, so we need to make some progress on this impasse in quantum understanding, and I suggest that testing for signalling is not beyond the bounds of current experiments.

It will be difficult if the signalling speed (the "speed of entanglement") is so fast as to be comparable with the minimum qubit switching time predicted by the energy-time uncertainty relation (see links above to limits on computing), since any experiment will have to distinguish the entanglement propagation speed from the quibit switching time.

In fact, if god's being a devil she might have made the signalling time smaller than we can measure classically, then we won't be able to distinguish the effect from an instantaneous one.

But for historical record, in case these forums are archived for future generations, I want to state I believe that signalling occurs in some not overly exotic non-classical space (so not some freaky fractal dimension topology or weird discrete construct).

I'm sure reality can't be completely bizarre, because if it was, evolution would have created beings to take advantage of the bizarreness. That's essentially why most paranormal stuff doesn't work, if it did it would have emerged in an obvious way from evolution, and we would have telepathic cats and levitating birds ;)

 

[DevilsAvocado]

Actually I thought it was a pretty good Monty joke. [PLAIN]https://www.physicsforums.com/images/smilies/smile.gif[/QUOTE]

(Thanks! but) "Look, matey," I do know there are 'customers' who "https://www.physicsforums.com/showpost.php?p=2709968&postcount=253"" about this very silly joke!

Given the weakness of the opposing arguments here, it appeared to me that many would get a false impression of excessive certainty of a particular view.

If you suggest: Running down the whole 18th century for an "optical solution", or disqualifying Einstein, Bohr, Bell & Aspect as bummers "who doesn’t care" – I’m with you all the way bro! (severe irony)

 

[DevilsAvocado]

The problem with that argument is that it's a struggle to explain multiparticle entanglement in quantum computers (and perhaps the conscious brain), since all the particles would have to occupy the same "thing" (or have some component of their positions in multidimensional space fixed) undisturbed for long periods of time.

I think it's easier to imagine that signalling between the particles occurs in some non-classical space.

...

But for historical record, in case these forums are archived for future generations, I want to state I believe that signalling occurs in some not overly exotic non-classical space (so not some freaky fractal dimension topology or weird discrete construct).

I'm sure reality can't be completely bizarre, because if it was, evolution would have created beings to take advantage of the bizarreness. That's essentially why most paranormal stuff doesn't work, if it did it would have emerged in an obvious way from evolution, and we would have telepathic cats and levitating birds ;)

Many BIG THANKS for that! It's one of the best post I’ve seen so far! Awesome!

But you still have to explain to me – if only one of these entangled photons can decide spin up/down – WHO decides!?

 

[DevilsAvocado]

I'm sure reality can't be completely bizarre, because if it was, evolution would have created beings to take advantage of the bizarreness.

Or put it this way:

Either our brains are incomplete and the reality of QM is fooling us all the time and every day, or QM (and/or GR) is incomplete?

But would incomplete brains discover a complete theory??

 

[DevilsAvocado]

... One explanation is that they are two aspects of the same thing that aren't in the same place.

As UN mentioned, you run into trouble with the complete madness that DrChinese has enforced into our heads – https://www.physicsforums.com/showthread.php?t=376225" ??

And in this case; there has to be four "aspects of the same thing", and this of course is going to get 'worse' in the future:

 

[DrChinese]

...Section VIII covers Bell's inequalities. I can't honestly disparage considerations that local realism may in fact be a dead horse. What I can disparage is the claim that it is certainly so. It's not entirely honest on either side of the fence.

Not sure I would agree with that assessment. Granted, that may not have been true in 1965, but we have had time to consider Bell since. I am somewhat familiar with this paper (I keep links on a lot of local realists for easy reference, and this was one). Not the first time violation of Bell-like inequalities have been alleged in classical situations. If you are interested in discussing this specific paper, I would be happy to. However, I don't sense that is the point you are making.

I think you are saying that the matter is not decided. And I think it quite is. Bell Inequalities are violated experimentally in agreement with the predictions of QM. EPR local realism is untenable. Now, keep in mind that in the intervening years since Bell, all kinds of entanglement phenomena has been discovered. With a green light from Bell, QM has made prediction after prediction which can be verified - none of which remotely smack of local realism and in fact get farther and farther away.

For example: in another thread, I presented evidence that particles outside each others' light cones can be entangled. It's going to be a cold day before that one can be explained classically.

 

[DevilsAvocado]

... I think you are saying that the matter is not decided. And I think it quite is.

DrC, would you say that "the fat lady has sung", even though we haven’t yet fully understood the complete 'mechanism' behind entanglement?

 

[DevilsAvocado]

What the he*k!? Frame Dragger is permanently banned?

 

[IcedEcliptic]

Opinions put aside, do the Bell Tests and ones that Dr. Chinese is speaking of mean that this is a settled issue? I am not in this community, so I do not know. It seems to me, that there is no classical means for this to occur, that separate sources entangle, game over, yes?

I am left with: Reality is not what I think it is from my daily life, and action in time and space is not ordered the way I expect it to be. Spatial separation may be meaningless when it does not change causality?

 

[DrChinese]

Opinions put aside, do the Bell Tests and ones that Dr. Chinese is speaking of mean that this is a settled issue? I am not in this community, so I do not know. It seems to me, that there is no classical means for this to occur, that separate sources entangle, game over, yes?

It is settled to the mainstream community. There are a few doubters. Of course, there are also doubters of a spherical Earth, General Relativity, the Big Bang, etc. If we found out everything we know is wrong, then this could be too.

 

[my_wan]

Not sure I would agree with that assessment. Granted, that may not have been true in 1965, but we have had time to consider Bell since. I am somewhat familiar with this paper (I keep links on a lot of local realists for easy reference, and this was one). Not the first time violation of Bell-like inequalities have been alleged in classical situations. If you are interested in discussing this specific paper, I would be happy to. However, I don't sense that is the point you are making.

I appreciate the offer, but your right, that's wasn't my intention. I tend to lean on the realist side, as a personal preference, and I'd do well just to hear out the objections. I have a lot of issues with the classical models suggested so far, but for reasons unrelated to EPR. Of the attempts at these models 't Hooft seem to be the most torturous. They're generally like trying to force fit a car motor on a moped, and explaining away the extra parts. Yet I still haven't found a fundamental reason why EPR must be defined in terms of a physical switch activated by a FTL mechanism. In fact it seems that not only does this FTL interpretation require assuming a realistic mechanism, contrary to the standard interpretation, but also assumes a particular type of physical character of this mechanism. Vector spaces and statistical ensembles both by their very nature allows an arbitrary number of parameters to be summed up in just a few variables. Ensembles only provide correlation, not causation, classical or otherwise.

I think you are saying that the matter is not decided. And I think it quite is. Bell Inequalities are violated experimentally in agreement with the predictions of QM. EPR local realism is untenable. Now, keep in mind that in the intervening years since Bell, all kinds of entanglement phenomena has been discovered. With a green light from Bell, QM has made prediction after prediction which can be verified - none of which remotely smack of local realism and in fact get farther and farther away.

Nobody can seriously question QM or the limits provided under Bell's Theorem. I'm aware of all sorts experiments from EPR where both detectors did the measurement first in their own frame, delayed choice, frame dependent correlations, Afshar, single photon pictures, pictures taken using photons that never seen the object being photographed, metamaterials, etc. I might have missed something, but I hope not. I'm presently considering a sort of delayed choice/Afshar hybrid. Still I have yet to see an empirically backed argument to rule out all class of models as generally defined by Relational QM.

For example: in another thread, I presented evidence that particles outside each others' light cones can be entangled. It's going to be a cold day before that one can be explained classically.

Yet therein lies the weakness of your case. Essentially 'entangled' means correlated. Thus your case holds under the assumption that correlation equals causation. Even wise tales warn of that one. The assumption that these properties are absolute real properties may turn out to be akin to assuming velocity is an absolute. Nobody is surprised that the relative velocity of distant objects instantly change with a local boost. The fact that entanglement can be manipulated, is frame dependent, actually lends some support to a purely relational interpretation.
http://arxiv.org/abs/quant-ph/0302095"
http://arxiv.org/abs/quant-ph/0205179"

So the objections I would like to hear is how to empirically rule out such models. I'm not asking any given interpretation to be proved one way or the other, merely that EPR correlations rule out this relational model class the same way it rules out a local real signal switching actual mechanisms. This would be trivial if an actual FTL message could be sent, otherwise it hinges on a correlation equals causation claim.

 

[IcedEcliptic]

It is settled to the mainstream community. There are a few doubters. Of course, there are also doubters of a spherical Earth, General Relativity, the Big Bang, etc. If we found out everything we know is wrong, then this could be too.

Are you telling me that the Earth is not flat? Hogwash sir! ;)

 

[jtbell]

Are you telling me that the Earth is not flat?

And it's not supported by turtles all the way down?

 

[DevilsAvocado]

And it's not supported by turtles all the way down?

No worries mate! I’ve got it all covered!

 

[DevilsAvocado]

... Essentially 'entangled' means correlated.

This is an interesting point (that can be repeated). Erwin Schrödinger’s term Verschränkung is translated to entanglement, and this is (according to Anton Zeilinger) not as describing as the German term.

Verschränkung translated to English:
interleave
interconnection
folding
crossing
clasping​

Anton Zeilinger visualizes verschränkung like this:

(Entanglement in Swedish is something like 'spaghetti'... maybe that’s why I sometimes have a hard time digest... )

 

[IcedEcliptic]

And it's not supported by turtles all the way down?

I believe in the great turtle pile as the only sane anchor in a mad universe. ;) heh

 

[jtbell]

(Entanglement in Swedish is something like 'spaghetti'... maybe that’s why I sometimes have a hard time digest... )

I wonder what it is in Finnish. (Being of Finnish-American background, I have a more than passing interest in the language, but I haven't tried to study physics in it.)

 

[zonde]

Opinions put aside, do the Bell Tests and ones that Dr. Chinese is speaking of mean that this is a settled issue? I am not in this community, so I do not know.

What do you mean by "settled issue"? Settled using scientific method or settled by general consensus?
Anyways there is quite a big hole in reasoning about discarding local realism. Bell theorem rests on QM prediction that prefect correlations for any same (or orthogonal too in case of photons) angles do not depend form detection efficiency.
This is testable prediction however it has never been tested.

You can read what is in wikipedia about http://en.wikipedia.org/wiki/Scientific_method" :
"1. Use your experience: Consider the problem and try to make sense of it. Look for previous explanations. If this is a new problem to you, then move to step 2.
2. Form a conjecture: When nothing else is yet known, try to state an explanation, to someone else, or to your notebook.
3. Deduce a prediction from that explanation: If you assume 2 is true, what consequences follow?
4. Test: Look for the opposite of each consequence in order to disprove 2. It is a logical error to seek 3 directly as proof of 2. This error is called affirming the consequent."

 

[DevilsAvocado]

I wonder what it is in Finnish.

...I’m not sure, but could it be Nokia...??

Noo sorry, entanglement = Lomittuminen, and the word for QM is really cool Kvanttimekaniikka. Just taste that word (imagine sitting in a real hot sauna), it’s definitely hotter than QM!

(P.S. There’s a "friendly war" between Finnish Nokia and Japanese/Swedish Sony Ericsson, but in the end we are all brothers and sisters, even in ice hockey! )

 

[my_wan]

[...](Entanglement in Swedish is something like 'spaghetti'... maybe that’s why I sometimes have a hard time digest... )

Reasonable synonyms in English, but I believe that's what Francis Bacon would refer to as an "idola fori" (idol of the marketplace). To say that a variable is entangled does not endow that variable with the realism of spaghetti. Now if these variables unambiguously possessed these presumed ontic qualities, then where's the FTL communicator? Without that your still stuck with interpretive ambiguity, though something clever in the vein of Bell's Theorem might pull it off.

The Monty Python humor is cool, but until EPR can directly address this relational class, rather than violating the relational objections to formulate arguments against it, it remains just humor. The only honest answer to the OP then remains: It's potentially possible, simply because nobody has any hard answers. I'm still waiting on a cleaner empirical rebuttal to the relational model class.

 

[zonde]

Thought that I might add something to my last post.
In wikipidedia "affirming the consequent" is described as negative thing without looking at positive sides of this approach. Really there are other occupations of people that take advantage of that approach - it's engineering.

So if we do not call modern QM a science but engineering then everything falls in places and all things are fine the way they are.

 

[DevilsAvocado]

... do not call modern QM a science but engineering ...

Healthy reflection zonde. This approach has the big advantage of eliminating any 'religious elements'. If you put your head in the sand at a construction site, then you risk being buried in cement. ()

I’ agree 99.9%, with reservation for the fact the whole universe is inside this "construction site", and this must have some influence on the matter...

 

[DevilsAvocado]

... Now if these variables unambiguously possessed these presumed ontic qualities, then where's the FTL communicator? Without that your still stuck with interpretive ambiguity, though something clever in the vein of Bell's Theorem might pull it off.

I agree.

I have tried many times, and this is last try (before maybe starting a new thread). I see two paradoxes in EPR/Bell test experiments:

1) The official "Spukhafte Fernwirkung".

2) The 'madness' of SYNCHRONIZED ENTANGLED OUTCOMES.

If we compare with the double-slit experiment, we don’t have this problem. The wavefunction (of the wave–particle duality) is propagating perpendicular towards the double-slit and passes simultaneously. No problem, no paradox.

Whereas in Bell test experiments we have a wavefunction of two particles (or more!), that are separated outside each other’s light-cones, and have this far been tested at 18 km separation.

Now, to have one influence the other we need "Spukhafte Fernwirkung". But this is not enough, some function/property/mechanism must also resolve which one of the particles is going to DECIDE the correlated outcome.

It won’t work if they are exactly synchronized, because this will create a conflict with QM, HUP and probability.

It will only work if they are unsynchronized, but then we run into problem with GR who says that in some frame of reference they will be exactly synchronized, and in another frame of reference Alice will set the outcome, and in another frame of reference Bob will set the outcome!?

>> This doesn’t work with current understandings of QM and GR!? <<​

(... as far as I can tell ...)

 

[IcedEcliptic]

Scandinavian languages make my brain hurt. Lovely to hear, but painful to read and pronounce.

 

[DevilsAvocado]

Scandinavian languages make my brain hurt.

Yeah, I hear you.

This guy has completely destroyed our reputation!

https://www.youtube.com/watch?v=<object width="480" height="385"><param name="movie" value="http://www.youtube.com/v/mbs64GvGgPU&hl=en_US&fs=1&rel=0&color1=0x006699&color2=0x54abd6"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/mbs64GvGgPU&hl=en_US&fs=1&rel=0&color1=0x006699&color2=0x54abd6" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="480" height="385"></embed></object>

 

[unusualname]

Here is a paper that shows a violation of Bell's inequalities in classical statistics, among other things.

Abstract: http://arxiv.org/abs/0906.4919" Section VIII covers Bell's inequalities. I can't honestly disparage considerations that local realism may in fact be a dead horse. What I can disparage is the claim that it is certainly so. It's not entirely honest on either side of the fence.

But he doesn't claim this supports local (deterministic) realism, instead he proposes that reality is based on "probabilistic realism":

“Probabilistic realism” starts from the premise that the most general fundamental description of reality is of statistical nature [13]. “Elements of reality”, which allow for definite predictions, correspond then to values of observables as well as to correlations. Let us consider the EPR case of two entangled spins, carried by spatially separated particles which originate from the decay of a spinless particle and therefore have total spin zero. In this case the element of reality is the maximal anticorrelation for all spin directions, rather than values of individual spins. This element of reality is revealed by measurements of both spins and has existed already before the first measurement. In contrast, the value of one of the spins is maximally undetermined before the first measurement and not an element of reality.
Due to the correlation, the two spins have to be considered as one system. Even for an arbitrarily large separation, such that signals cannot be exchanged any longer, we cannot divide the system into two independent subsystems, consisting of one of the spins each. The correlation between the two spins is then nonlocal.

which is hardly what most of you local realists mean by local realism :)

I think I prefer nonlocal deterministic realism to this suggestion anyway, and I'm sure the most profitable way forward is to determine possible non-local models of reality, in that regard papers like this one An experimental test of non-local realism are interesting (rules out a class of non-local models)