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

[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)

 

[ThomasT]

It's clear that Bell Test (violation) experiments are correct (to anyone sensible), and it's also clear that Special Relativity is correct, so to account for entanglement we need either "magic" or a FTL causal mechanism that doesn't contradict SR.

There's almost universal agreement that the tests are correct. But neither magic nor ftl transmissions (nor aliens, etc.) are necessary to understand why the correlations exceed the limits on explicit lhv accounts of them.

To understand why BIs are violated it's necessary to compare the formal requirements, as set forth by Bell, with the experimental setups to which they're being applied (formal requirements that any explicit local hidden variable model of the joint, entangled, situation must meet). It should become clear that the variables which determine individual detection rates can't be made to (can't be put into a form which would) account for the joint detection rates, because they aren't the determining factors in that situation. Rather it's relationships between these variables that's being measured in the joint context. These relationships are joint hidden parameters that are being measured by a joint instrumental variable. This is what the 'quantum nonseparability' of the situation physically refers to. QM gives a correct account of the joint, entanglement, situation by not separating its components.

The above point is the key to understanding what Bell's theorem means and why it's impossible to have a local hidden variable model of entanglement. It's not that Bell was wrong or that he unwittingly made a faulty lhv model. Making a lhv model of entanglement is kind of a catch-22. The only way to represent the joint situation with local hidden variables happens to be incompatible with the demands of the situation that it's trying to model. An lhv account of the joint, entangled, situation must necessarily be an incorrect account of that situation. This has been proven by Bell and others (see David Mermin's, "Hidden variables and the two theorems of John Bell", Rev. Mod. Phys., Vol. 65, No. 3, July 1993). So, BIs (and other 'no lhv' theorems) based on the requirements necessary to construct any explicit lhv model of the joint, entangled state, experimental situation must, necessarily, be violated -- and this has nothing to do with nonlocal or ftl communication between the separated entangled quanta or the separated filtering and detection devices. The joint experimental situation is just, in Bell's words, "incompatible with separable predetermination". This doesn't mean that there aren't separate particles that have predetermined unknown individual properties. It just means that the joint experimental situation can't be modeled in those terms. (What sometimes sets people on the wrong path is Bell's statement in the conclusion of his 1964 paper, "On the Einstein Podolsky Rosen Paradox": "In a theory in which parameters are added to quantum mechanics to determine the results of individual measurements, without changing the statistical predictions, there must be a mechanism whereby the settings of one measuring device can influence the reading of another instrument, however remote." Which is correct of course. However, since there's no particular reason to believe that our universe might work that way independent of 'no lhv' theorems, and since BI violations can be explained without such a mechanism, then there's no particular reason to invent such a mechanism.)

Once that's understood, then it remains to understand how the correlations can be produced in a universe in which the principles of SR and local action hold. It should be clear enough that if there's some predetermined underlying relationship between, say, the spins of two photons, and that if these photons are jointly analyzed by crossed polarizers, then the correlations which result are pretty much what would be expected in a locally causal c-limited universe. Local predetermination of individual properties is incompatible with qm, because, for the reasons mentioned above, accounts of joint, entangled state, experimental situations in those terms are, necessarily, incompatible with those experimental situations.

This is not to say that the underlying mechanisms which result in entanglement correlations are completely, or even well, understood. They aren't by any means. And understanding that a local common cause for the underlying entanglement isn't ruled out by 'no lhv' theorems is just a beginning to any approach that's in line with relativistic restrictions. So, it's suggested that, before weird and absurdly strange scenarios are offered to account for the BI violations and entanglement stats, maybe the focus should stay on the subtleties of the still fascinating, even without any artificially added wierdness, facts of the science and analysis and interpretation that promise to facilitate a better understanding.

So, for the record, I agree with those (eg., David Mermin, see his "What Do These Correlations Know about Reality? Nonlocality and the Absurd) who think that positing the existence of, eg., nonlocality is not in keeping with the best practice of scientific inquiry.

 

[my_wan]

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.

This is at the core of the problem. Yet the justification that one must have actually influenced the other, at the time of measurement, is predicated on the unreality during transit and reality at the time of measurement. If these correlations were actually present during transit, then no such 'communication' is needed. The only way to deny this possibility is to deny the reality posited by such models during transit, then requiring what has been denied at the time the measurement takes place. No mechanism is required to "DECIDE" the correlation if it already exist.

You then made a more specific claim, that without a valid response moots my argument above.

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

Here you specified "exactly synchronized". But "exactly" has implications that may not be valid. I'll use a well known paper by Hall and Reginatto to illustrate.
http://arxiv.org/abs/quant-ph/0102069"

http://arxiv.org/abs/quant-ph/0102069]An[/PLAIN] exact uncertainty principle, formulated as the assumption that a classical ensemble is subject to random momentum fluctuations of a strength which is determined by and scales inversely with uncertainty in position, leads from the classical equations of motion to the Schrodinger equation. Thus there is an exact formulation of the uncertainty principle which precisely captures the essence of what is "quantum" about quantum mechanics.

Thus, by analyzing HUP as something somewhat analogous to Brownian motion, a version of HUP was derived from which the Schrodinger equation could then be directly derived. You should also note that this assumed a "classical ensemble", not an absolute valued variable in and of itself. Thus the implication by "exactly synchronized" does not entail that the measured variable is itself an absolute valued variable. Yet we all know that a large ensemble of random variables can be characterized by non-random values, and non-local effects are not needed to arrive at this value. Nor are we required to assume these variables don't exist without measurement, even though they lack real meaning wrt individual elements of a defining ensemble, classical or otherwise. "Exactly", "HUP", "QM", and "probability" has not only been maintained, but defined by and extended to include the Schrodinger equation in exact uncertainty case.

This addresses the "exactly synchronized" issue, but a more general issue implied in your rebuttal needs mentioned. Though I doubt you intended to imply this. In general when speaking of what is in "conflict" with a theory we are limited to empirical "conflict", irrespective of how incongruent the principles used to arrive at the empirical content appears to be. It's my opinion that ontologies have a symmetry similar to coordinate dependence, which we know is untenable in the general case. There can also be a form of covariance between incongruent but empirically equivalent ontologies. Many debates result from these sometimes equivalent but incongruent ontologies, and we call it arguing semantics.

 

[DrChinese]

...It should become clear that the variables which determine individual detection rates can't be made to (can't be put into a form which would) account for the joint detection rates, because they aren't the determining factors in that situation. Rather it's relationships between these variables that's being measured in the joint context. These relationships are joint hidden parameters that are being measured by a joint instrumental variable...

Again, no. In a local hidden variable model, each observer is measuring a separate reality. So there is no JOINT observable (or context). This is by definition, but also comes from the EPR definition of an element of reality: if the outcome can be predicted with certainty, then there is an element of reality. And in a local world, what happens here does not affect what happens there.

If there is a "joint detection parameter" observable, it is global. That does not work in a local world either. So you may be correct, but you are not describing a local realistic model.

 

[my_wan]

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.

(Bolding and underlining added to make my point.)

Here it says: "This element of reality is revealed by measurements of both spins and has existed already before the first measurement." Thus no signaling mechanism is required to establish a correlation when the measurement takes place. It goes on to say: "In contrast, the value of one of the spins is maximally undetermined before the first measurement and not an element of reality." But what does "maximally undetermined" mean here wrt one spin, that doesn't exist with both spins? It is our knowledge that is "maximally undetermined", not the spin state itself. Consider the following analogy.

You have a red and a blue marble. You have a machine package them in separate boxes without any knowledge of what color is in each box, and ship one around the world. Now, in the case of both marbles, like both spins, the color of both marbles is fully determined before the first measurement, as specified in the quote. Also, the color of the marble in anyone box is "maximally undetermined", because you don't know which marble is in which box, as specified in the quote. Yet the colors are correlated, because knowledge of one provides full knowledge of the other. You can only assume a FTL mechanism if you deny that the marbles had a color before opening one of the boxes.

Now we also know that these QM correlations cannot correspond to singular properties of a singular object, like in the marble sense. Bell's ingenuity made that crystal clear. If the logic holds in the QM sense, then the properties must be defined by ensembles, group behavior/relations which defines the properties. We know, classical or not, that a large number of random variables can be summed as a single well defined variable. Only when we put these variable into two groups, we can't define what each group separately will sum to, without first measuring at least one group. We also know that disparate emergent properties of ensembles can be formalized as if a single entity, if we drop (or don't know) the identifiers which define them.

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

I run into realists 'priest' all the time, and these are a bigger pain than they are worth. However, given the misrepresentation apparently provided in your rebuttal, I think it would be a bit difficult to define what one particular realist means. I'm not even sure "most" is definable.

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)

I take the opposite tack, but given what we know at this point it would be unreasonable for me to insist my approach will be the most profitable. I'm not so certain as you have stated yourself to be here. I am a bit more certain that certainty in your own view can be a liability to a fruitful search, even if your lucky enough to be essentially right. My own modeling efforts actually include FTL variables of sorts, they just happen to be unusable for EPR and similar effects.

 

[my_wan]

Again, no. In a local hidden variable model, each observer is measuring a separate reality.

Funny, I've never seen it that way. There's MWI which is a class of its own, but certainly not universal to lhv models. There's another way I could interpret this, but it would be essentially equivalent to stating that two observers that measure the velocity of the same object differently must be measuring a "separate reality". Of course general covariance is a difficult issue in QM.

So there is no JOINT observable (or context). This is by definition, but also comes from the EPR definition of an element of reality: if the outcome can be predicted with certainty, then there is an element of reality. And in a local world, what happens here does not affect what happens there.

Yet I still haven't even seen an acknowledgment of definitions not contained in the EPR definition, nor what those definitions entail. If you restrict the discussion solely to realism as defined by EPR, then logical validity goes without saying. Yet there are entire well defined classes of models which EPR definitions don't apply. You can legitimately ignore them as a personal preference, but stating what certainly is or isn't so, on the basis of a priori rejections of logical classes, doesn't follow.

If there is a "joint detection parameter" observable, it is global. That does not work in a local world either. So you may be correct, but you are not describing a local realistic model.

I give a marble analogy of a joint detection parameter to unusualname. Then pointed out how EPR puts constraints on this logic through ensembles rather than singular objects with singular properties. I'd still like to hear a rebuttal that does a prior reject the reasoning in order to reject the reasoning.

 

[unusualname]

So, for the record, I agree with those (eg., David Mermin, see his "What Do These Correlations Know about Reality? Nonlocality and the Absurd) who think that positing the existence of, eg., nonlocality is not in keeping with the best practice of scientific inquiry.

yes, but it's much more fun to speculate on non-locality :)

When De Broglie suggested wave-particle duality in 1923, it was a pretty crazy looking suggestion at the time which bypassed a lot of tortuous alternative philosophical and analytical proposals, but turned out to be a spectacularly successful scientific model.

It's quite possible that Entanglement "paradoxes" will turn out to be due to us being restricted to observing a projection of reality, so we don't really see the real picture, like in the holographic principle which, amongst other things, proposes that all information in a volume is obtainable from the surface area surrounding it.

So the non-locality may be illusory due to us being restricted to observing a subset of reality (although it appears to be non-local behaviour in that subset)

 

[IcedEcliptic]

Ah yes, the science of personal preference.

 

[my_wan]

Ah yes, the science of personal preference.

It plays a legitimate role in science when dealing with open questions, unless you think a psychic would do better directing research. It makes no sense for everybody to explore exactly the same set of assumptions, and such preferences distribute these searches more realistically. The danger is when we wrongly insist opposing assumptions are invalid, and artificially restrict research to our personal preferences. Certainly there are closed questions, but we must be careful not to over generalize and close questions that the physics involved didn't specifically close.

 

[DevilsAvocado]

This is at the core of the problem.

I’m sincerely thankful for this comment. I was about to give up, convincing myself I was "lost in translation". Thank you so very much for this.

No mechanism is required to "DECIDE" the correlation if it already exist.

This makes me a little 'nervous' again... do you mean that LHV is still a reasonable possibility??

Here you specified "exactly synchronized". But "exactly" has implications that may not be valid.

Bad formulation of me, I’m sorry. What I wanted to pin down is the problem of Relativity of Simultaneity (RoS), and the fact that entanglement seems to be in need of a global NOW, to work properly.

One weird way to get rid of this problem is to accept Relational Blockworld (RBW) – No movement of particles in spacetime whatsoever.

Another is Many Worlds Interpretation (MWI) – EPR is no paradox and works just fine, in branched and separated universes.

And we can rule out a universal global NOW – since, for example, the GPS satellites needs adjustments for relativistic time dilation effects, essential for the functioning of the system.

So if we skip "interpretations under development" and look at what we 'have today', I say we have some 'trouble' in getting entanglement working.

My hope is that the QM world isn’t that 'crazy' that it’s impossible to 'talk about', and make some sense, in plain language. I could of course be totally wrong; QM world is 'crazy' and/or impossible to talk about. But I sure hope not. (Note: I’m not talking about superposition etc, simultaneously spin up/down – that’s not crazy, just weird.)


In an attempt to get over 'ontology & semantics', I’ll take a real dramatic example:

1) Alice & Bob are going to play "Russian Entangled Roulette".

2) Two revolvers with all rounds are connected to the measuring apparatus, and adapted to Alice & Bob’s heads.

3) If spin up (+) is measured, the revolver will not fire. If spin down (-) is measured, the revolver will fire.

4) Alice & Bob are separate by 1 ly, with the source halfway.​

PROBLEM:
In one observer's reference frame we could see Alice’s photon hitting the polarizer first, and measure (+), thus killing Bob by deciding he is going to measure (-).

In another observer's reference frame we could see Bob’s photon hitting the polarizer first, and measure (-), thus saving Alice by deciding she is going to measure (+).

Would you be Alice lawyer in court?

Or what I’m really getting at – how do Alice & Bob’s photons know which reference frame they are in? Either the wavefunction/entanglement is broken/measured – or it is not. You can’t be in a state 'in-between' or 'both', can you? The wavefunction can’t collapse 'twice', can it?

 

[IcedEcliptic]

It plays a legitimate role in science when dealing with open questions, unless you think a psychic would do better directing research. It makes no sense for everybody to explore exactly the same set of assumptions, and such preferences distribute these searches more realistically. The danger is when we wrongly insist opposing assumptions are invalid, and artificially restrict research to our personal preferences. Certainly there are closed questions, but we must be careful not to over generalize and close questions that the physics involved didn't specifically close.

Pretty way of saying that what you and zonde and thomast are on about is not really physics.

 

[my_wan]

This makes me a little 'nervous' again... do you mean that LHV is still a reasonable possibility??

In principle yes, but EPR correlations do place very definite restrictions on any such models. I thought I covered those conditions in my responses and papers I referenced for details. I give a marble analogy but Bell's theorem does in fact rule out such singular objects with singular properties. EPR requires some further constraints as follows:
1) The LHV's can't be singular objects, but rather local ensembles, roughly analogous to what any classical waveform is.
2) The properties, presumed non-local, can't be an absolute observer independent character of the ensemble. Rather a property relative to an observer, the experimental apparatus in this case. This is why I said the fact that EPR correlations are frame dependent lends support to this view, and linked papers to demonstrate.
With these two conditions, Bell's theorem is silent. It neither proves it right or wrong, unlike the marbles.

Bad formulation of me, I’m sorry. What I wanted to pin down is the problem of Relativity of Simultaneity (RoS), and the fact that entanglement seems to be in need of a global NOW, to work properly.

Yes indeed, IIF a signaling mechanism is required. However, if you accelerate, there's no reason to be surprised that all distant objects change apparent velocity instantly, exactly according to your definition of simultaneity. Yet no signaling is involved. If 1) and 2) above apply, then this is all that's involved with EPR correlations. In fact, the difficulties RoS imposes seems to lend more support to this view.

One weird way to get rid of this problem is to accept Relational Blockworld (RBW) – No movement of particles in spacetime whatsoever.

Yes, I've only been aware of RBW a few days, and it's very interesting. However, fundamentally RBW appears to take advantage of the relational view I've been discussing, in an upside down sort of way. The Blockworld does require the entire context to be accounted for.

Another is Many Worlds Interpretation (MWI) – EPR is no paradox and works just fine, in branched and separated universes.

Yes, except it lacks empirical justification, beyond the need for sweeping a range of issues under the rug. Maybe that can change, but so far all I see is a lot of stacking of dependent variables.

And we can rule out a universal global NOW – since, for example, the GPS satellites needs adjustments for relativistic time dilation effects, essential for the functioning of the system.

So if we skip "interpretations under development" and look at what we 'have today', I say we have some 'trouble' in getting entanglement working.

Yes, very endemic trouble. This is why I look at the issues from a class level, rather than specific models. Hopefully this will be useful in providing some viable clues where to go from here.

My hope is that the QM world isn’t that 'crazy' that it’s impossible to 'talk about', and make some sense, in plain language. I could of course be totally wrong; QM world is 'crazy' and/or impossible to talk about. But I sure hope not. (Note: I’m not talking about superposition etc, simultaneously spin up/down – that’s not crazy, just weird.)

Yep, I'm in this boat, but realistically we can't demand it a priori. So I begin with the strongest causality, and give up what the physics says I must, like the marble analogy under EPR is fully untenable. The there are a whole range of notions, common here, which give up even more but are quiet reasonable assumptions, with a fair likelihood of paying off.

In an attempt to get over 'ontology & semantics', I’ll take a real dramatic example:

1) Alice & Bob are going to play "Russian Entangled Roulette".

2) Two revolvers with all rounds are connected to the measuring apparatus, and adapted to Alice & Bob’s heads.

3) If spin up (+) is measured, the revolver will not fire. If spin down (-) is measured, the revolver will fire.

4) Alice & Bob are separate by 1 ly, with the source halfway.​

PROBLEM:
In one observer's reference frame we could see Alice’s photon hitting the polarizer first, and measure (+), thus killing Bob by deciding he is going to measure (-).

In another observer's reference frame we could see Bob’s photon hitting the polarizer first, and measure (-), thus saving Alice by deciding she is going to measure (+).

Would you be Alice lawyer in court?

Or what I’m really getting at – how do Alice & Bob’s photons know which reference frame they are in? Either the wavefunction/entanglement is broken/measured – or it is not. You can’t be in a state 'in-between' or 'both', can you? The wavefunction can’t collapse 'twice', can it?

If the relational interpretation holds, then it makes no difference what reference frame they are in. The measurements don't make the choice, they merely finalize them. Fundamentally, in this case, it would be no different from all bullets in one gun without knowing which, and both triggers are pulled. The superposition of both guns tells us exactly how many bullets there is. Without looking we could know nothing about the bullets in anyone gun. This is untenable given Bell's theorem, unless the guns are ensembles that can overlap, and you positioned properly relative to the gun. Only the formalism does not make a distinction between an actual overlap of ensembles and an apparent overlap due to our lack of location knowledge. We merely superimpose all possible locations as if all possibilities was the reality, justified on the fact that the waveforms can and do overlap, and required for valid statistical answers.

Years ago, in Jr High, I read "In Search of Schrodinger's Cat". By the time it finally got around to saying what was supposed to be so weird, I thought I had guessed the answer. I figured it was a cross frame effect in relativity. Several years later, when I finally learned how untenable this was, it unambiguously brought home the meaning of general covariance. I even embarrassed myself on this forum once, falsely thinking somebody else made this mistake. You can reverse the apparent order of events visually, but once you account for the intervals involved no change in event ordering occurs. You can compress and stretch them, or even time for an individual, but event ordering remains the same. If this was possible you could use a pair of moving known frames to measure the distance to various stars, but it's not. Yet if a faster than light mechanism actually existed you could. EPR doesn't 'effectively' work to allow changing real event ordering either, which lends to the relational interpretation. Yes, I would be the lawyer.

 

[my_wan]

Pretty way of saying that what you and zonde and thomast are on about is not really physics.

Haven't payed much attention to what zonde and ThomasT have said, though I believe it was ThomasT that was backed into an untenable corner iirc. I'm more interested in views that can potentially demonstrate that I'm wrong. Pretending that a class of models that are ruled out by physics (EPR) when they are not is 'effectively' a pretense about being physics. Thus the debate belongs on the issue of how I'm wrong, and how the relational interpretation is ruled out by EPR correlations. Not on labels you can impose on me to impune.

In particular what can be addressed in the general sense is this paper:
http://arxiv.org/abs/quant-ph/0604064"

This paper actually weakens the notion of realism, at least as it relates to the variables under question, yet contains the points I have been making. It's not me making demands on how things are, only pointing out that a certain class being rejected is not ruled out by EPR correlations.

Since I haven't really received a proper rebuttal, perhaps some questions to clear up the distinctions I'm making between what is and isn't ruled out by EPR experiments, or attempts to paraphrase what I've said so I can see what the issue is.

 

[DrChinese]

Haven't payed much attention to what zonde and ThomasT have said, though I believe it was ThomasT that was backed into an untenable corner iirc. I'm more interested in views that can potentially demonstrate that I'm wrong. Pretending that a class of models that are ruled out by physics (EPR) when they are not is 'effectively' a pretense about being physics. Thus the debate belongs on the issue of how I'm wrong, and how the relational interpretation is ruled out by EPR correlations. Not on labels you can impose on me to impune.

In particular what can be addressed in the general sense is this paper:
http://arxiv.org/abs/quant-ph/0604064"

This paper actually weakens the notion of realism, at least as it relates to the variables under question, yet contains the points I have been making. It's not me making demands on how things are, only pointing out that a certain class being rejected is not ruled out by EPR correlations.

Since I haven't really received a proper rebuttal, perhaps some questions to clear up the distinctions I'm making between what is and isn't ruled out by EPR experiments, or attempts to paraphrase what I've said so I can see what the issue is.

Rovelli's interpretation is generally considered to be acceptable, i.e. it is not local realistic. Therefore it follows Bell.

 

[unusualname]

Haven't payed much attention to what zonde and ThomasT have said, though I believe it was ThomasT that was backed into an untenable corner iirc. I'm more interested in views that can potentially demonstrate that I'm wrong. Pretending that a class of models that are ruled out by physics (EPR) when they are not is 'effectively' a pretense about being physics. Thus the debate belongs on the issue of how I'm wrong, and how the relational interpretation is ruled out by EPR correlations. Not on labels you can impose on me to impune.

In particular what can be addressed in the general sense is this paper:
http://arxiv.org/abs/quant-ph/0604064"

This paper actually weakens the notion of realism, at least as it relates to the variables under question, yet contains the points I have been making. It's not me making demands on how things are, only pointing out that a certain class being rejected is not ruled out by EPR correlations.

Since I haven't really received a proper rebuttal, perhaps some questions to clear up the distinctions I'm making between what is and isn't ruled out by EPR experiments, or attempts to paraphrase what I've said so I can see what the issue is.

Well speaking for myself, and continuing the "bull in the china-shop" method of scientific argument (although crude, it does create a clear path), I simply don't see why anyone would prefer pleading to alternative wholesale interpretations of reality rather than accepting some rather straightforward adjuncts to the classical reality we already know and love so well.

EPR fails and shows we need an additional (or alternative) model to explain the observations of quantum theory. Well, since what fails is local classical causality, why not just accept that there's a mechanism that allows non-local causality? As long as the mechanism is consistent with other classical observations everything's sweet, n'est-ce pas?

To be consistent with classical physics, the non-local causal mechanism can't be observable classically (obviously), so let's just chuck in a non-classical space using your favourite topological construct and propose that communication occurs in that space.

That also conveniently allows us to have a real wave-function, consisting of the non-classical signal's effects on classical space at the instersection points of the topology with classical space.

That also allows us to suggest this is the space in which our consciousness exists, and clears up the mind-body duality to boot! (Evolution sussed out how to sustain consciousness in material bodys without much trouble, so it must be constructed from something that pervades the environment)

Then all we need, is some quantitative predictions from the model, such as delayed entanglement propagation, which we then observe.

There, that's much more reasonable than relational interpretrations of reality and other such malarky. :)

 

[RUTA]

There, that's much more reasonable than relational interpretrations of reality and other such malarky. :)

I can't speak for the (few) others who prefer violations of realism to locality, but I don't want to give up relativity of simultaneity (no preferred frame) and I don't want to talk about the "future causing the past" (if the future is already "there," then you've a blockworld and nothing "happens" in a blockworld anyway) -- either or both of these obtain with causal non-locality. No matter the mechanism, if you have A causing B when A and B are space-like related, you have causal non-locality, so I opted for nonseparability. I think it's healthy for the overall effort at unification to have advocates for all the possible interpretations of QM.

 

[DevilsAvocado]

EPR requires some further constraints as follows:
1) The LHV's can't be singular objects, but rather local ensembles, roughly analogous to what any classical waveform is.
2) The properties, presumed non-local, can't be an absolute observer independent character of the ensemble. Rather a property relative to an observer, the experimental apparatus in this case. This is why I said the fact that EPR correlations are frame dependent lends support to this view, and linked papers to demonstrate.
With these two conditions, Bell's theorem is silent. It neither proves it right or wrong, unlike the marbles.

I’m going to give you my layman assumption why I believe LHV is a dead parrot.

Please feel free to correct me (if and when I’m wrong):

• YES, it’s impossible to make any distinction whatsoever between LHV and QM predictions on a singular object/particle/photon, and that’s why Einstein & Bohr had the long and unresolved EPR-debate.
  
  
• In 1964 John Bell introduces the brilliant idea to enforce probability into the measurement of EPR, to be able to distinguish LHV from QM predictions. John Bell implements this in the form of varying the angles of the analyzers.
  
  
• There is still no way to calculate QM probability on a single entangled pair of photons.
  
  
• Today’s technique allows us to "http://arxiv.org/PS_cache/arxiv/pdf/0704/0704.2529v2.pdf" ". Meaning – we can send one pair of entangled photons at a time and measure the outcome.
  
  
• There is no need to 'speed up' the excitation of entangled photon pairs to get an analogy to a "classical waveform". There could be one year between every pair – and the QM predictions are still there (in the same way as Double-slit electron diffraction*).
  
  
• Some argue that the entangled pair is disturbed by environment and is impossible to measure with any accuracy. This is somewhat true; there is noise which disturbs the system. However the use of http://en.wikipedia.org/wiki/Coincidence_counting_(physics)" is "improving the signal to noise ratio to the extent that the quantum behavior can be studied, without removing the noise completely".
  
  
• With the described conditions above, we can send 100 pairs of entangled photons towards the polarizer’s which are RANDOMLY ALIGNED AFTER THE ENTANGLED PAIR LEFT THE SOURCE, where the polarizer’s are http://arxiv.org/abs/0803.2425" . Meaning – there is absolutely NO WAY for the entangled pair to AGREE on the outcome since they are outside each other’s light cone when the parameters for the experiment are finally settled.
  
  
• QM predictions stipulate that if we send 100 entangled pairs of photons and the angle of the polarizer is 22.5°, we should get a correlation of 0.71, meaning 71 pairs are correlated (+,+) and 29 pairs are non-correlated (+,-) (-,+). And this is exactly what happens – EVERY TIME in thousands of performed experiments. And there is NO WAY for LHV to even get close to the QM 0.71 correlation, LHV always gives a 0.5 correlation.
  
  
• To argue that noise is by chance creating this seemingly correlation – is not healthy science.
  
  
• To argue that defective optics in crystals is by chance creating this seemingly correlation – is not healthy science.
  
  
• To argue that there is an interpretation (which has not yet been confirmed) who makes everything a non-issue – is (maybe) not healthy science.

This is why I believe: Local Hidden Variable Theory = Norwegian Blue Parrot


Double-slit electron diffraction*
https://www.youtube.com/watch?v=<object width="480" height="385"><param name="movie" value="http://www.youtube.com/v/FCoiyhC30bc&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/FCoiyhC30bc&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>

If the relational interpretation holds, then it makes no difference what reference frame they are in. The measurements don't make the choice, they merely finalize them.

AFAICT this makes the "Norwegian Blue Parrot" moving a little again...

You can compress and stretch them, or even time for an individual, but event ordering remains the same. If this was possible you could use a pair of moving known frames to measure the distance to various stars, but it's not. Yet if a faster than light mechanism actually existed you could. EPR doesn't 'effectively' work to allow changing real event ordering either, which lends to the relational interpretation. Yes, I would be the lawyer.

It’s possible I have misunderstood the 'problem' of RoS & EPR, but if we for awhile pretend that LHV is a working solution, then it would all be a question of 'good old relativity'. Your example with "all bullets in one gun without knowing which" is as good as any EPR setup – it’s a question of a random value that we yet don’t know.

BUT according to all I have said so far – the outcome is settled at the measurement and are instantaneously effecting to outcome of the entangled partner.

Thus in one observer's reference frame Alice would physically causing Bob’s death, and in the other observer's reference frame Alice would be completely innocent.

I do think that would cause some trouble for you as 'the lawyer'.

 

[ThomasT]

Again, no. In a local hidden variable model, each observer is measuring a separate reality. So there is no JOINT observable (or context).

Right. But the joint, entangled situation requires a joint observable and a joint measurement parameter. So, do you see why lhv theories must be ruled out and why that doesn't tell us anything about Nature?

If there is a "joint detection parameter" observable, it is global. That does not work in a local world either. So you may be correct, but you are not describing a local realistic model.

I'm not trying to describe a local realist model. I'm trying to explain why a viable local realist model of entanglement can't be done.

 

[my_wan]

Ok, the reason I got rather insistent was due to the unqualified claim that Bell's theorem proves that local realism is untenable. I take this kind of statement in the general sense, irrespective of semantics. The following quote calls this into question. I'll outline my reading of Rovelli, so perhaps we can clear the undefined issues.

Rovelli's interpretation is generally considered to be acceptable, i.e. it is not local realistic. Therefore it follows Bell.

Pedantically , "not local realistic" does not in itself entail consistency with Bell. Only consistency with empirical detection statistics does that. But more importantly, Relational EPR is local and the realism has been weakened in the interpretation, not removed. Does this justify the position that Relational EPR is not locally realistic? This is strongly dependent on how the realism has been weakened, so we'll look at that a bit closer.

http://arxiv.org/abs/quant-ph/9609002"
It should be noted the RQM is formulated as an "information theory", rather than a physical theory. This is justified by the fact that what we measure are events rather than things. These events must also involve the observer, measuring device, which is itself an ensemble of events, to have any empirical meaning. The classical notion of observation, without non-trivially interacting with the system being measured, is untenable. The notion of an object in front of you that doesn't interact with the Universe in general is empirically moot. Thus reality in the empirical regime is a verb, rather than a noun. An ensemble of verbs at that. RQM does not speak of unmeasured variables, because that includes information not available in an information theory. Neither does it claim this unavailable information is not fully contained in the local ensemble being measured. That requires the assumption that what is unknown is non-existent, which exceeds the scope of the information available.

Weakening Realism
Also very important is the notion of "observer-independent values of physical quantities". By describing reality solely in terms of verbs, Bell's theorem is sidestepped, because Bell's theorem presumes spin state is a noun, or at least has a one to one ontological correspondence with a noun (lhv). If it is a 'relative' value of an ensemble (system verbs) wrt another ensemble (observer verbs) then an absolute spin state, assumed by Bell, is untenable, at least wrt the empirical information. As a theory of information, counterfactual reasoning is not strictly valid, and obtaining information via an interaction does not entail obtaining information not already present in the local ensemble. In the words of Rovelli:

http://arxiv.org/abs/quant-ph/0604064)]From[/PLAIN] the relational perspective the Heisenberg picture appears far more natural: \psi codes the information that can be extracted from past interactions and has no explicit dependence on time; it is adjusted only as a result of an interaction, namely as a result of a new quantum event relative to the observer. If physical reality is the set of these bipartite interactions, and nothing else, our description of dynamics by means of relative states should better mirror this fact: discrete changes of the relative state, when information is updated, and nothing else. What evolves with time are the operators, whose expectation values code the time-dependent probabilities that can be computer on the basis of past quantum events.

Thus, realism is in fact fully maintained in Relational EPR, in the form of verbs rather than nouns, and no mechanism is required to transfer information, at the time of the measurement, from space like separated regions. The information is fully contained in local events (verbs). The distance between such ensembles, and RoS, is then a moot issue.

Strengthening Realism
What is not provided by RQM are noun predicates that define the events (verbs). This is justifiable, even if they exist, given that any ontic entity, which does not interact with the Universe, lacks any empirical relevance whatsoever. Our experience of the world is fully and exhaustively defined by these verbs (events). Yet if Einstein realism holds, at least in principle, it must be in terms of nouns on which the verbs are relativistically predicated. Such attempts are often constructed as generalized thermodynamic models. The one I referenced previously in this thread actually constructed such EPR correlations from thermodynamic ensembles, among other things. The only response I got from that was that the reference was already known.

Summation
Although Relational EPR weakens Einstein realism in an empirical sense, it does not remove it in principle. Nor is the events themselves, void of any noun predicates, anything other than empirically real events, which requires no space like separated detection of events. It is only by assuming that a lack of information entails the lack of a relativistic properties that evidence of FTL can be constructed. I'm therefore inclined to say:
1) Relational EPR is a local realistic interpretation, with the caveat that the relative 'events' are real irrespective of lacking noun predicates or observer independent variables.
2) Local realistic models can, at least in principle, be formulated consonant with Bell and Relational EPR, with the caveat being that the empirical content is contained in the form of relativistic (observer characterized) verbs.
3) Bell's theorem fails to rule out lhv models in which observables are relativistic observer dependent characterizations of an ensemble of verbs.

 

[DevilsAvocado]

In particular what can be addressed in the general sense is this paper:
http://arxiv.org/abs/quant-ph/0604064"

Eureka! I think I got it (somewhat)!
Since we know there can’t be a global universal NOW (RoS), there can’t be a global universal REALITY (for all observers), right!?


http://arxiv.org/PS_cache/quant-ph/pdf/0604/0604064v3.pdf" is a cool paper!


And I must read it many times more to digest all. Rather 'shockingly' there seems to be parallels to what I was asking about in https://www.physicsforums.com/showpost.php?p=2716407&postcount=324", and the question of a wavefunction that collapses 'twice'.

An indication of this fact is in the well-known difficulty of describing and interpreting the relativistic transformation law of the wave function, when measurements involve observers in relative motion.

Relational EPR is very cool in the sense that it tries to 'merge' GR & QM by a 'slight' modification of both interpretations of Einstein & Bohr, smart and very 'diplomatic'.

I guess my 'rant' in https://www.physicsforums.com/showpost.php?p=2717199&postcount=331" is completely obsolete in the view of Relational EPR... sorry.


It looks like even DrChinese is out on thin ice...?

We call locality the principle demanding that two spatially separated events cannot have instantaneous mutual influence. We will argue that this is not contradicted by EPR type correlations, if we take the relational perspective on quantum mechanics.

Locality is at the very roots of RQM, in the observation that different observers (in general distant from one another) can have different descriptions of the same system.

I must digest and read again, but I shall return. Thanks for the link.


[PLAIN]http://upload.wikimedia.org/wikipedia/en/thumb/b/b0/Observer-observed.gif/350px-Observer-observed.gif
Observer O measures the state of the quantum system S

 

[my_wan]

Well speaking for myself, and continuing the "bull in the china-shop" method of scientific argument (although crude, it does create a clear path), I simply don't see why anyone would prefer pleading to alternative wholesale interpretations of reality rather than accepting some rather straightforward adjuncts to the classical reality we already know and love so well.

Yes, I seek as few adjuncts to classical physics as possible. What I hope to have made clear, unless someone can provide a good counterargument, is that, at least in principle, it's possible to maintain both locality and realism. If someone can posit a rational FTL mechanism, that's empirically useful, I'll accept that as a local mechanism. The speed C is the limit of locality as we know because that's what it defines given our present understanding, not because it is, if faster effects exist. However, simply as a method of sweeping EPR under a rug is not a valid justification in my view.

EPR fails and shows we need an additional (or alternative) model to explain the observations of quantum theory. Well, since what fails is local classical causality, why not just accept that there's a mechanism that allows non-local causality? As long as the mechanism is consistent with other classical observations everything's sweet, n'est-ce pas?

Ok, perhaps so, but before that can be stated without equivocation, the objections I have articulated must be addressed. Merely stating it is so does not make it so. As for my reasons for avoiding non-local effects: Because the conceptual and mathematical nightmare it creates in trying to get it to coexist with what we know is beyond belief. Even QM presently is a tame beast in comparison. If it remains "consistent with other classical observations" then it must lack empirical meaning, outside of sweeping conceptual issues under the rug. The constraints of RoS are quiet severe.

To be consistent with classical physics, the non-local causal mechanism can't be observable classically (obviously), so let's just chuck in a non-classical space using your favourite topological construct and propose that communication occurs in that space.

Some of my own modeling attempts explicitly allow certain variables of sorts to randomly exceed C. Yet it's unworkable as an EPR mechanism, or any FTL summation. So I'm not adverse to FTL mechanisms as such, but merely to poke it in like some surgical instrument accidentally sewed into your body by a surgical doctor doesn't cut the mustard for me.

That also conveniently allows us to have a real wave-function, consisting of the non-classical signal's effects on classical space at the instersection points of the topology with classical space.

FTL is not a requirement for real wavefunctions. It does seem require a separation, at least in principle, between the waveform (itself an ensemble), and the ensemble imposed by on it solely by limitations of specific knowledge of that ensemble.

That also allows us to suggest this is the space in which our consciousness exists, and clears up the mind-body duality to boot! (Evolution sussed out how to sustain consciousness in material bodys without much trouble, so it must be constructed from something that pervades the environment)

Ouch, I don't have a problem with the mind/body connection. I can even provide an empirically realistic self organizing 'toy' mind model, including memory, qualia, and evolutionary stages, with nothing more than metronomes and springs. Mathematically it's not really fundamentally new, but makes it easy to visualize how it leads to the empirical data. I generally find this kind of question involves the composition fallacy, and a failure to appreciate the nature and ubiquity of emergent properties. For this reason I find it interesting, but outside the scope here.

Then all we need, is some quantitative predictions from the model, such as delayed entanglement propagation, which we then observe.

Perhaps even something that''ll fill the holes left by Bell's theorem.

There, that's much more reasonable than relational interpretrations of reality and other such malarky. :)

I suspect that in labeling it "malarky" it's being interpreted within a singular myopic ontology. It was intentionally restricted in terms of an "information theory" for empirical and model independent consistency. Read my last response to DrC and I included at least one ontological model extension. If I took it as a final answer to the issues posed by QM, which I don't accept without GR, it would in fact be at the very least pointless. Understand what actually makes it work, and it gives you tools to think about real models, rather than just boring interpretations.

The most fundamental point I'm trying to make here is that, contrary to common opinion, EPR correlations don't entirely rules out all locally realistic theories. I've also provide the caveats that such models would require. I still have some interesting points to articulate for DevilsAvocado's last post. I look forward to defeat, if that is the truth, but the points actually need addressed for that to happen.

 

[RUTA]

Summation
Although Relational EPR weakens Einstein realism in an empirical sense, it does not remove it in principle. Nor is the events themselves, void of any noun predicates, anything other than empirically real events, which requires no space like separated detection of events. It is only by assuming that a lack of information entails the lack of a relativistic properties that evidence of FTL can be constructed. I'm therefore inclined to say:
1) Relational EPR is a local realistic interpretation, with the caveat that the relative 'events' are real irrespective of lacking noun predicates or observer independent variables.
2) Local realistic models can, at least in principle, be formulated consonant with Bell and Relational EPR, with the caveat being that the empirical content is contained in the form of relativistic (observer characterized) verbs.
3) Bell's theorem fails to rule out lhv models in which observables are relativistic observer dependent characterizations of an ensemble of verbs.

I spent hours yesterday with my philosopher of science colleague reading van Fraassen and Rovelli on RQM. We think we have it figured out (it's a challenge, thus the van Fraassen's paper). Crudely, it's information theory plus the light cone structure. Overall, physics is about information and special relativity and QM are rules for the exchange of information. RQM says information exchange is local per SR with correlations per QM. RQM does not provide an underlying mechanism for those QM correlations, so we were frustrated until we figured that out and quit looking for his ontology.

Given what I (mis?)understand about RQM, I would say it does not accomplish local realism, weakly or otherwise. He's in the nonseparable (not realism) class, clearly, but exactly how he doesn't say. I'm inclined to think he's saying QM is fundamental, so there is no "why" for its correlations. This is like SR postulating the constancy of c. It's a postulate, so there is no explanation for "why" everyone measures the same speed for light. It's just a brute fact about information and its exchange.

BTW, we think RBW can be used to provide a "why" for information theory and RQM, but that's another story.

 

[my_wan]

Eureka! I think I got it (somewhat)!
Since we know there can’t be a global universal NOW (RoS), there can’t be a global universal REALITY (for all observers), right!?

Yes, but there can be a form of general covariance. So in a relativistic sense it still describes the same thing, with different correlation statistics, measurements, etc. Not a separate reality as opined earlier in this thread. We already empirically know that EPR correlations are frame dependent.

http://arxiv.org/PS_cache/quant-ph/pdf/0604/0604064v3.pdf" for more detail on the interpretation as it relates to QM. Be aware that, as an interpretation, it remains model neutral. That doesn't preclude ontological extensions that go beyond purely the measured information without violating the legitimacy of RQM, as I pointed out in my last post to DrC. The sum total of all measurements is after all a complete specification of what we know or can empirically know, with or without theories that synthesis it in workable models.

And I must read it many times more to digest all. Rather 'shockingly' there seems to be parallels to what I was asking about in https://www.physicsforums.com/showpost.php?p=2716407&postcount=324", and the question of a wavefunction that collapses 'twice'.

Yes, I only mentioned the "twice collapsing wavefunction" once in passing. Actually my version was a collapsed wavefunction that wasn't collapsed for another observer. This can easily lead outside the EPR question of this thread, but I tend to think the formalized wavefunction consist of real quasi-localized fields we call particles, smeared (superimposed) over all possibilities not entirely relevant to a single self interacting particle (ensemble). This would indicate a the collapse didn't localize the particle, it merely reduced all possibles, from lack of a priori knowledge, to just the information relevant to that one particle. A large number of individual detections of self interacting particles must still be representative of all possibilities, as the formalized wavefunction requires.

Relational EPR is very cool in the sense that it tries to 'merge' GR & QM by a 'slight' modification of both interpretations of Einstein & Bohr, smart and very 'diplomatic'.

This "diplomacy" has strengths and weaknesses, and was predicated more on the notion of an "information theory" consonant with QM than diplomacy. It allows the interpretation to be model independent, and still allow logical cogency to be analyzed. Its weakness is that it doesn't by itself provide pointers to how to construct a model, consonant with RQM and/or GR, that could potentially lead us to new empirical content or unification. It's not that hard to access a models cogency with RQM after the fact though. Does P=NP?

I guess my 'rant' in https://www.physicsforums.com/showpost.php?p=2717199&postcount=331" is completely obsolete in the view of Relational EPR... sorry.

Yes, the single particle verses statistical ensembles of possibilities which may only be relevant in part to that single particle verses statistics of a large number of detections where all possibilities becomes relevant makes it somewhat difficult to think about. We know that particles are self interacting, so the wavefunction is relevant, at least in part, to single particles. Though I think it most likely that all possibilities is a useful fiction in the single particle case, while the particle is still a quasi-localized ensemble (field). You also seem to have gotten the issues that a Universal now would impose on present physics if it defines something that can't exist via RoS. If it's found to exist then it can't exist at any given time relative to a particular observer. It only goes stark raving mad from there, however easy it is to say now is now for me. I'll bow to anybody that can pull it off.

It looks like even DrChinese is out on thin ice...?

So am I. I've included a lot of opinion about what is possible here. However, I'm fairly confident in the main points of my claim as they relate to the EPR subject of this thread. Not as a fact of how nature is, but in the claim that EPR correlations fail to rule out the class of LHV theories specified.

I must digest and read again, but I shall return. Thanks for the link.

[PLAIN]http://upload.wikimedia.org/wikipedia/en/thumb/b/b0/Observer-observed.gif/350px-Observer-observed.gif
Observer O measures the state of the quantum system S

If you could, continue to try and poke holes in the possibility of LHV models of the class I've specified. It's difficult to learn from merely chasing support for a preexisting viewpoint. I'd like to hear your perspective of what you get from it anyway, and any questions or problems that I failed to address.

 

[unusualname]

Yes, I seek as few adjuncts to classical physics as possible. What I hope to have made clear, unless someone can provide a good counterargument, is that, at least in principle, it's possible to maintain both locality and realism. If someone can posit a rational FTL mechanism, that's empirically useful, I'll accept that as a local mechanism. The speed C is the limit of locality as we know because that's what it defines given our present understanding, not because it is, if faster effects exist. However, simply as a method of sweeping EPR under a rug is not a valid justification in my view.

Ok, perhaps so, but before that can be stated without equivocation, the objections I have articulated must be addressed. Merely stating it is so does not make it so. As for my reasons for avoiding non-local effects: Because the conceptual and mathematical nightmare it creates in trying to get it to coexist with what we know is beyond belief. Even QM presently is a tame beast in comparison. If it remains "consistent with other classical observations" then it must lack empirical meaning, outside of sweeping conceptual issues under the rug. The constraints of RoS are quiet severe.

Some of my own modeling attempts explicitly allow certain variables of sorts to randomly exceed C. Yet it's unworkable as an EPR mechanism, or any FTL summation. So I'm not adverse to FTL mechanisms as such, but merely to poke it in like some surgical instrument accidentally sewed into your body by a surgical doctor doesn't cut the mustard for me.

FTL is not a requirement for real wavefunctions. It does seem require a separation, at least in principle, between the waveform (itself an ensemble), and the ensemble imposed by on it solely by limitations of specific knowledge of that ensemble.


Ouch, I don't have a problem with the mind/body connection. I can even provide an empirically realistic self organizing 'toy' mind model, including memory, qualia, and evolutionary stages, with nothing more than metronomes and springs. Mathematically it's not really fundamentally new, but makes it easy to visualize how it leads to the empirical data. I generally find this kind of question involves the composition fallacy, and a failure to appreciate the nature and ubiquity of emergent properties. For this reason I find it interesting, but outside the scope here.

Perhaps even something that''ll fill the holes left by Bell's theorem.

I suspect that in labeling it "malarky" it's being interpreted within a singular myopic ontology. It was intentionally restricted in terms of an "information theory" for empirical and model independent consistency. Read my last response to DrC and I included at least one ontological model extension. If I took it as a final answer to the issues posed by QM, which I don't accept without GR, it would in fact be at the very least pointless. Understand what actually makes it work, and it gives you tools to think about real models, rather than just boring interpretations.

The most fundamental point I'm trying to make here is that, contrary to common opinion, EPR correlations don't entirely rules out all locally realistic theories. I've also provide the caveats that such models would require. I still have some interesting points to articulate for DevilsAvocado's last post. I look forward to defeat, if that is the truth, but the points actually need addressed for that to happen.

The problem you have is that not many people working in modern physics really care that EPR violations can be explained away by philosophical arguments about the nature of reality. You've mentioned the relational interpretation and an interpretation based on "probabilistic realism" (which I did reply to btw, I think you missed that since you claim your post was ignored) which are fun for those of a philosophical bent to ponder but for pragmatic scientists they are not very useful.

The relational interpretation is particularly unappealing, it just comes across as a clumsy way of extending einstein's spacetime relativity.

You (too) easily claim that consciousness may be explained by emergent properties in complex systems, as if that was a simple issue in comparison to explaining nonlocality!

The physical world is stuff A, consciousness is stuff B. Science will have to accept sooner or later that we haven't included stuff B in our models of reality.

Once we accept that stuff B has to be included we begin the next stage of our scientific development.

I don't think we need to throw deep philosophical arguments in just yet, science is about making theoretical models of how things work so as to make predictions or explain "why" something happens or is the way it is. Science starts with observations, and what I observe is that there is a physical world and there is my conscious awareness of this physical world. My conscious awareness is clearly not part of the physical world, so to model it scientifically I suggest it exists in is own separate "space", which mathematically we can model with extra dimensions appended to physical space or other topological constructs.

Our conscious thoughts seem to be able to have effects in the physical world and the physical world certainly affects our consciousness so we assume the two spaces are joined and can influence each other.

We can also assume consciousness is mundane and not something mystical, since it emerged from a mundane process, evolution.

Given that the only phenomena in science we know to be in conflict with classical local realism are quantum effects, it seems natural to assume consciousness and quantum effects are related, in particular it seems that entanglement and quantum computation gives a natural setting for our consciousness.

It also allows a natural solution to the problem of free-will: without conscious beings the universe is essentially the result of statistical physics. However, if we actually "are" a quantum system it seems reasonable to assume we can influence or "choose" quantum states in our own quantum system, so free-will is a conscious being selecting quantum states in his consciousness (which propagate to effects in the physical world). We do have to allow that an individual particle also has free-will, but if it's not related to any "desires" in a complex consciousness the "choices" made by individual particles are indistinguishable from random.

(Why we have desires to influence quantum states one way or another is complex, and the problem of the human condition)

Rather than argue subtle and complex philosophical issues this raises I like to imagine a simple "thought experiment":

Imagine a sophisticated computer based on Mars, which knows all current physics, observing the Earth's exterior for the last few billion years. The computer would record all physical events, eruptions, meteor impacts, climate change etc and fit them to its physics model without much trouble. But then in 1957 it sees a metal object shoot up from the surface and deliberately orbit the earth, in the years following it sees another metal object travel to the moon. How does it explain that with physics? Have conservation laws been broken? How can those events fit a physical model of the Earth which started as a relatively simple physical object, a big ball of molten rock.

Heck, we could even blow the Earth to pieces, maybe even the universe.

Without including consciousness (stuff B) as an additional component to reality in your scientific models you get nonsense.

So putting it all together, and returning to the OP's question, I suggest entanglement is due to signalling in the space of stuff B. It doesn't conflict with classical causality because the entire causal chain is restricted to the space of stuff B, although it may give rise to curious observations of backward events in the space of stuff A (classical space), it doesn't allow FTL signalling in the space of stuff A.

I don't even think this is a controversial model, it's bleedin' obvious.

 

[DevilsAvocado]

My conscious awareness is clearly not part of the physical world

Huh? Can that really be proven?

without conscious beings the universe is essentially the result of statistical physics.

Huh?? So the first 400 millions yrs after BB, before the first star was formed – and consciousness was impossible – the universe was a deterministic machine without HUP...??

But then in 1957 it sees a metal object shoot up from the surface and deliberately orbit the earth, in the years following it sees another metal object travel to the moon. How does it explain that with physics?

If the sophisticated Mars computer had a really good telescope, it could see the first tree deliberately rise from the mud. We don’t apply consciousness to a tree, do we...??

 

[DevilsAvocado]

If you could, continue to try and poke holes in the possibility of LHV models of the class I've specified.

You bet!
()

I think it’s time for some reconciliation... my brain is smeared out (superimposed) over all possibilities in trying to understand EPR – from DrC’s experimental-down-to-earth, to RUTA’s 'strange' RBW, and your 'special' RQM, and now comes an unusualname and propose that consciousness is the key...??

I got to think... (for a change ;)

 

[ThomasT]

In a local hidden variable model, each observer is measuring a separate reality. So there is no JOINT observable (or context).

That's right. (You're almost there.) But entanglement IS a JOINT observational context. (Let that sink in for a moment.)

Now, is what's being measured in the separate measurements at A and B the same as what's being measured jointly?
The answer is no. That's why I said:

It should become clear that the variables which determine individual detection rates can't be made to (can't be put into a form which would) account for the joint detection rates, because they aren't the determining factors in that situation.

... in a local world, what happens here does not affect what happens there.

That's right. But there are only two values for |a - b| where A and B are perfectly correlated (anticorrelated), and these perfect correlations are compatible with the assumption that the relationship between the entangled photons has a local common cause.

But, you might counter, the full range of entanglement stats can't be reproduced by a lhv description of the joint context. And that's correct, but it's because what's being measured in the separate measurements at A and B is not the same as what's being measured jointly.

A local hidden variable account of the joint context requires the parameter determining joint detection RATE (this parameter is the relationship BETWEEN the relevant individual property or properties of the disturbances incident on a and b) to be described in terms of the parameter determining individual detection SEQUENCE (this parameter is the relevant individual property or properties).

Hence our catch-22 situation: there's no way to model the joint situation using individual properties and get the full range of entanglement stats -- yet an lhv model requires the joint state to be described in terms of the individual properties, properties which, it's quite easy to see, can't possibly be put into a form which would account for the full range of entanglement stats. It's like requiring a peg to fit into a hole that, if you just look at the situation, it can't possibly fit into, and then making all sorts of wild speculations and new realities to account for why it doesn't fit into the hole.

If there is a "joint detection parameter" observable, it is global. That does not work in a local world either.

(1) The joint measurement parameter is |a - b|. (2) What |a - b| is measuring is the relationship between the counter-propagating disturbances. Both (1) and (2) are compatible with the assumption of c-limited locality.

So you may be correct ...

It is correct. But the presentation needs some refining.

... but you are not describing a local realistic model.

Hopefully it will become clear that I'm not trying to do that, but rather explain why such a model is impossible, and why the impossibility of constructing such a model doesn't imply nonlocality (or ftl info transfer) in Nature.

 

[ThomasT]

EPR fails and shows we need an additional (or
alternative) model to explain the observations of quantum
theory.

There is a local causal explanation for EPR. Just as
there is a local causal explanation for any entanglement stats. It's
just that these stats can't be predicted by an explicit lhv model. And
the reason for that has to do with a disparity between the requirements
of an explicit lhv model and the experimental situation that is being
modelled, independent of the consideration of locality, which is what
I've been talking about in my many posts in this thread.

Well, since what fails is local classical causality
...

No, that's not what fails. What fails is the requirement
that an experimental situation be modeled in terms of variables which
are irrelevant wrt the experimental situation.

... why not just accept that there's a mechanism
that allows non-local causality?

Because there's a simpler
explanation for why BIs are violated that doesn't require nonlocality
or any interpretation of qm other than the standard one.

-----------snip malarky -----------

There, that's much more reasonable than relational
interpretrations of reality and other such malarky. :)

No, it's malarky.

 

[ThomasT]

Since I haven't really received a proper rebuttal, perhaps some questions to clear up the distinctions I'm making between what is and isn't ruled out by EPR experiments, or attempts to paraphrase what I've said so I can see what the issue is.

The challenge is to explain why lhv descriptions of entanglement are impossible without resorting to artificial constructions of 'reality', or positing nonlocality or ftl transmissions, etc. I think that's possible.

Read what I've posted. Because if it's correct, then all of the speculative interpretations of qm which purport to account for violations of BIs are simply not necessary to account for violations of BIs -- and a rather well established interpretation of qm, namely dBB theory, might then need to be viewed as quite probably just wrong wrt its explicit nonlocality.

As long as we continue thinking that we don't or can't know exactly why BIs are violated, then the door is open to lots of stuff that would otherwise just be dismissed as being obviously silly.

But, what I'm saying is that we can know why BIs are violated and that it's right in front of us, and all we have to do is compare the requirements of an lhv theory with the reality (ie., the preparations) of entanglement experiments and it's immediately apparent why lhv descriptions of these experimental situations are impossible -- without resorting to nonlocality, or ftl, or dBB, or MWI, or RQM, or RBW, etc.

If one of your electrical appliances doesn't turn on, what's the FIRST thing you do? Check to see that it's plugged in, right? Unfortunately the equivalent isn't happening wrt speculations surrounding the incompatibility between lhv models and entanglement.

 

[unusualname]

Huh? Can that really be proven?

No, it's just an observation (that consciousness is not part of the physical world)

Huh?? So the first 400 millions yrs after BB, before the first star was formed – and consciousness was imp ossible – the universe was a deterministic machine without HUP...??

Well the uncertainty principle still applied, but (assuming no other conscious lifeforms had formed) the universe was deterministic in the sense of statistical physics, but remember that classical determinism doesn't imply perfect predictability due to the limitations imposed by chaos theory, even in a simple 3-body planetary system.

If the sophisticated Mars computer had a really good telescope, it could see the first tree deliberately rise from the mud. We don’t apply consciousness to a tree, do we...??

Ok a joke, but a tree doesn't do anything beyond what we can explain by simple physics, it doesn't have sophisticated inputs from the physical world (no non-trivial sense organs) either. Simple physics can't explain the journey taken by the Apollo rocket to the moon, since it was guided by conscious choices. I noticed some links were posted above to preprints discussing the behaviour of entangled systems in moving classical frames http://arxiv.org/abs/quant-ph/0302095 and http://arxiv.org/abs/quant-ph/0205179 , these results show that the classical observables in entangled systems vary according to the reference frame, but that's not unexpected since I would expect a form of special relativity to apply to any additional spaces appended to classical reality, just that we don't need to assume c is the limiting speed in that space. :)

 

[unusualname]

There is a local causal explanation for EPR. Just as
there is a local causal explanation for any entanglement stats. It's
just that these stats can't be predicted by an explicit lhv model. And
the reason for that has to do with a disparity between the requirements
of an explicit lhv model and the experimental situation that is being
modelled, independent of the consideration of locality, which is what
I've been talking about in my many posts in this thread.

By "explanation" I mean one that makes sense scientifically.

Because there's a simpler
explanation for why BIs are violated that doesn't require nonlocality
or any interpretation of qm other than the standard one.

-----------snip malarky -----------

Your "simple explanation" is the most convoluted one in the whole thread, at least mine is "simple" ;)

 

[IcedEcliptic]

By "explanation" I mean one that makes sense scientifically.



Your "simple explanation" is the most convoluted one in the whole thread, at least mine is "simple" ;)

I have been quietly reading this for some time, and I agree. I don't ascribe to the RUTA or unusualname view, but I recognize them as scientific and plausible.

Zonde, ThomasT, you are selling your own crazed theories.

 

[my_wan]

You bet!
()

I think it’s time for some reconciliation... my brain is smeared out (superimposed) over all possibilities in trying to understand EPR – from DrC’s experimental-down-to-earth, to RUTA’s 'strange' RBW, and your 'special' RQM, and now comes an unusualname and propose that consciousness is the key...??

I got to think... (for a change ;)

I've provided no better reason to presume my approach is any better than anybody elses. I would encourage not attaching to a particular view for purely anesthetic reasons. The point I hope to make clear is that EPR correlations, in spite of the very real constraints it imposes, does not support nor rule out local causality in general. That is the point relevant to the OP.

Personally, interpretations for their own sake is of very little interest to me. As a group they provide a space of possibilities, much like EPR correlations provides limits. I also consider observationally equivalent ontologies to the ontological interpretations provided. If an ontologically pleasing interpretation is all that is at stake, QM is just fine as is. But we still have the issue how to get QM and GR to play well together, with a formalism that provides empirical data, more than mere interpretations. The notion that interpretation alone is a useful construct is a stretch for me, especially with bigger game potentially available. Also, the notion that some things simply are because they are (fundamental) may in fact be so, but I think that presuming a priori that they are can be a self defeating self imposed limitation. The history of science supports the notion that fundamental principles can often be derived from more fundamental constructs.

So all the various interpretations have value, in their own way, but attempting to convince me that a given interpretation is the one true interpretation, like a one true absolute frame of reference, is a lost cause in my view. This multiplicity of views and approaches has value, often not as incongruent as supposed if you don't take ontologies as absolutes, and is an important part of the search.

 

[DevilsAvocado]

So all the various interpretations have value, in their own way ...

Okay, I hear you... so how do we proceed to find the TRUTH!?

()

 

[DevilsAvocado]

No, it's just an observation (that consciousness is not part of the physical world)

I’m curious about this. It’s our brains that have 'trouble' with EPR – not EPR itself (meaning the experiment ;).

I agree, it’s very "natural to assume consciousness and quantum effects are related", even though I personally don’t think it has anything to do with 'binary computing' – with the main objection that the brain is a living biological tissue with a electrochemical network, connected to a living body, which in turn are (must be) connected to other living bodies/brains in a social and cultural network, where the human language is the most important factor (put a newborn in an isolated box, and you will have a creature that has more common with a crazy chimpanzee than a human), whereas the quantum computer is stone dead, and completely alone, even if it has a NIC.

Could you imagine two quantum computers in love, 'connected' by a Cat5!?
Edit: And now I just realized netdating!

(My personal wild guess is that the brain is instead of binary 1/0, is utilizing 'analog chemistry' to build up 'thresholds' to trigger 'events', like falling in love, etc...)

Well the uncertainty principle still applied, but (assuming no other conscious lifeforms had formed) the universe was deterministic in the sense of statistical physics, but remember that classical determinism doesn't imply perfect predictability due to the limitations imposed by chaos theory, even in a simple 3-body planetary system.

Agree, and we can probably be 100% sure that no other conscious was available < 400 myrs, except if life could emerge from free-streaming radiation or cold dark matter...? This would be a miracle that would put EPR in 'kindergarten'!

... a tree doesn't do anything beyond what we can explain by simple physics ...

Huuum, can we really describe DNA and the "life of a tree" by "simple physics"...? Where is that formula??

I noticed some links were posted above to preprints discussing the behaviour of entangled systems in moving classical frames ...

The paper http://arxiv.org/abs/quant-ph/0205179" is very interesting (why did I miss that?). This seems to prove that the wavefunction is Lorentz invariant (covariant?), and my 'speculation' about RoS wavefunction contradictions is in-valid... still it’s hard to accept that the joint entanglement of the wavefunction can 'survive' this 'environment':

[URL]http://upload.wikimedia.org/wikipedia/commons/e/e4/Lorentz_transform_of_world_line.gif[/URL]
Views of spacetime along the world line
of a rapidly accelerating observer moving
in a 1-dimensional "universe"

 

[zonde]

I have been quietly reading this for some time, and I agree. I don't ascribe to the RUTA or unusualname view, but I recognize them as scientific and plausible.

Zonde, ThomasT, you are selling your own crazed theories.

Scientific means that there is something testable about idea apart from hand waving.
Where is that part in RUTA or unusualname views that you call them scientific?

My idea however can be tested easily any time (assuming of course you have equipment for basic Bell inequality test).
Another thing is that my idea is based on things that you observe in experiments and not on what's in other people heads. So you can call my idea crazy but it's much tighter bound with what you can observe out there compared to those plausible other ideas.