Joy Christian, Disproof of Bell's Theorem

[mbd]

Behind a paywall, unfortunately. Can you summarize the distinction as Blaylock sees it?

http://arxiv.org/abs/0902.3827

 

[Maui]

If one constructs a theory that is local, realistic, but not counterfactual definite, then the theory is not ruled out by Bell's Theorem. It is an open question whether one exists.

The interesting space is in the extremely subtle difference between realism and counterfactual definiteness. Here's a paper with a good explanation of the distinction:

http://arxiv.org/abs/0902.3827

An equivalent way to look at it is to consider the experimental constraints that the assumptions of Bell's Theorem require. A recent paper by Antonio Di Lorenzo explains, and defines quite clearly, the assumptions from a more experimental point of view.

http://pra.aps.org/pdf/PRA/v86/i4/e042119

I haven't looked at the papers but did you mean superdeterminism by local realism without counter-factual definiteness? If yes, it has been beaten to death here. If no, doesn't realism require counterfactual definiteness? Why?

 

[mbd]

I haven't looked at the papers but did you mean superdeterminism by local realism without counter-factual definiteness? If yes, it has been beaten to death here.

Not necessarily. Superdeterminism is only a consequence of a system having realism sans counterfactual definiteness if the system is the last word.

Reality is rich with systems that, at one level of detail, have qualities and structure that are qualitatively different from systems at higher or lower levels of details. There's no definitive evidence to suggest that QT is anything different.

A system that is local, realistic, not counter-factual definite, and that is experimentally distinguishable from QT is the thing to test to answer the question.

 

[DrChinese]

A system that is local, realistic, not counter-factual definite, and that is experimentally distinguishable from QT is the thing to test to answer the question.

As I mentioned in a message to you, your concept requires definitions that are not generally accepted. There is no such thing (except in the mind of a small group of fervent local realists) as the accepted idea that Bell assumes some distinction between counterfactual definiteness and realism.

Realism is defined as a collection of elements of reality assumed to exist simultaneously. That is from EPR (1935). Bell demonstrated that such elements cannot have values which will match the usual predictions of QM. This has absolutely nothing to do with constraints on measuring multiple angles etc. You don't have to measure anything. Bell says that if locality and realism are assumed, you cannot get the QM predicted results. Vice versa, if you get the QM predicted results then at least one of the assumptions of locality and realism are false.

My point is that anyone, anytime, is free to define realism some other way than EPR did. If you do, you may not get the Bell result. But so what? It is the EPR definition that is the gold standard. And with that definition gets you the Bell result.

 

[Nugatory]

I haven't looked at the papers but did you mean superdeterminism by local realism without counter-factual definiteness? If yes, it has been beaten to death here. If no, doesn't realism require counterfactual definiteness? Why?

The paper is arguing for multiple-worlds as a local and realistic interpretation that is not counterfactually definite (no history includes the measurement not made) but also is not even factually definite (you get different facts in diferent histories). It's internally consistent and actually kinda easy to swallow... Although that may be because if you've managed to gulp down the multiple-worlds camel, after that everything is easy to swallow.

The first section has a really good explanation of the small-angle version of Bell's argument.

 

[mbd]

As I mentioned in a message to you, your concept requires definitions that are not generally accepted. There is no such thing (except in the mind of a small group of fervent local realists) as the accepted idea that Bell assumes some distinction between counterfactual definiteness and realism.

For the sake of getting past semantics, then, by realism I mean "scientific realism" per the article I linked to above (here too) which illuminates the distinction.

http://arxiv.org/abs/0902.3827

It must be noted, though, that the definition of "reality" in EPR (1935) is not in fact a definition but, rather, a criterion with scope limited only to the purposes of the argument. And, there is no definition of reality at all in Bell (1964). Bell's own recognition of the implicit assumptions in his work played out over subsequent years.

Einstein's definition is: "If, without in any way disturbing a system, we can predict with certainty (i.e., with probability equal to unity) the value of a physical quantity, then there exists an element of physical reality corresponding to this physical quantity." He then goes on to say that this a sufficient, but not necessary, condition of reality.

 

[DrChinese]

For the sake of getting past semantics, then, by realism I mean "scientific realism" per the article I linked to above (here too) which illuminates the distinction.

http://arxiv.org/abs/0902.3827

It must be noted, though, that the definition of "reality" in EPR (1935) is not in fact a definition but, rather, a criterion with scope limited only to the purposes of the argument. And, there is no definition of reality at all in Bell (1964). Bell's own recognition of the implicit assumptions in his work played out over subsequent years.

Einstein's definition is: "If, without in any way disturbing a system, we can predict with certainty (i.e., with probability equal to unity) the value of a physical quantity, then there exists an element of physical reality corresponding to this physical quantity." He then goes on to say that this a sufficient, but not necessary, condition of reality.

He also says that these must be considered as simultaneously real... that any other view is unreasonable. Back then, the semantics was not debated quite like today. Bell didn't even bother to mention the definition, thinking (I believe) that EPR's take was adequate for scientists.

 

[audioloop]

the definition of realism/reality goes beyond physics.

 

[Nugatory]

the definition of realism/reality goes beyond physics.

Quite true, but because physics tries to describe the R-word world, it's not always practical to completely avoid using the R-word.

Often (perhaps in all pre-QM physics and outside of discussions of QM interpretations) this isn't a problem. Samuel Johnson ("I refute it thus") and Potter Stewart ("I know it when I see it") are good enough, and detailed hair-splitting discussions of what the R-word means are irrelevant distractions.

But when we do discuss QM interpretations... It's good practice to try to be explicit about what meaning we have assigned to the R-words, CFD, and the like.

 

[Darwin123]

the definition of realism/reality goes beyond physics.

I thought this was a Physics Forum!
I am so sorry. I am in the wrong place!

 

[mbd]

The conceptual and practical challenges in defining "realistic" are a consequence of the fact that we're trying to talk about the system and the interfaces to that system as if these are separate things.

By separating the system in this way, we see experiments to be the act of making inputs to that system, collecting outputs from that that system, and then evaluating the information with mathematical models. We're asking: does our mathematical model of what's inside produce the same outputs as Nature when given the same inputs?

But, the veracity of what we infer from this process depends critically on the veracity of our understanding of what are the inputs and outputs.

The decades long process of recognizing, defining, and experimentally ruling out, the various loopholes in EPR experiments shows the significant challenges of this process.

In CHSH, we assume that we are inputing two particles into two measuring apparatuses. Well, more precisely, we assume that if two particles are detected sufficiently coincidentally, then we have input two particles into the measuring apparatuses. We don't know this, however.

This is an assumption that, it would seem, we cannot experimentally prove due to Heisenberg. Why? If we are to detect the presence of the particles prior to their entry into the measuring apparatuses, we break their presumed entanglement and thus lose the correlations of measurements.

So, we are precluded from experimentally confirming the veracity of our understanding of the inputs and the outputs to this experiment. Just like we cannot measure, with arbitrary precision, both the momentum and location of a particle, we cannot know with conclusive precision the inputs and outputs to this experiment.

This is, at least conceptually, the essence of the challenge of performing a "loophole free" CHSH experiment.

 

[DrChinese]

The conceptual and practical challenges in defining "realistic" are a consequence of the fact that we're trying to talk about the system and the interfaces to that system as if these are separate things.

By separating the system in this way, we see experiments to be the act of making inputs to that system, collecting outputs from that that system, and then evaluating the information with mathematical models. We're asking: does our mathematical model of what's inside produce the same outputs as Nature when given the same inputs?

But, the veracity of what we infer from this process depends critically on the veracity of our understanding of what are the inputs and outputs.

The decades long process of recognizing, defining, and experimentally ruling out, the various loopholes in EPR experiments shows the significant challenges of this process.

In CHSH, we assume that we are inputing two particles into two measuring apparatuses. Well, more precisely, we assume that if two particles are detected sufficiently coincidentally, then we have input two particles into the measuring apparatuses. We don't know this, however.

This is an assumption that, it would seem, we cannot experimentally prove due to Heisenberg. Why? If we are to detect the presence of the particles prior to their entry into the measuring apparatuses, we break their presumed entanglement and thus lose the correlations of measurements.

So, we are precluded from experimentally confirming the veracity of our understanding of the inputs and the outputs to this experiment. Just like we cannot measure, with arbitrary precision, both the momentum and location of a particle, we cannot know with conclusive precision the inputs and outputs to this experiment.

This is, at least conceptually, the essence of the challenge of performing a "loophole free" CHSH experiment.

As I have repeated, you are free to define "realistic" differently than others. I would not agree with your characterization of this discussion per your above. There is a good definition and it is not much debated (except by local realists looking for an out).

Further, the concept of a so-called loophole free Bell test is quite outside the scope of this thread. It really belongs in a separate one, and this is a fairly technical subject. Again, your characterization of the debate here is not accurate. All of the loopholes have been closed, for example. The current debate is more around having a single experiment where all are closed simultaneously. Here are a couple of recent papers by some of the top teams in this area:

http://arxiv.org/abs/1111.0760

http://arxiv.org/abs/1206.2289

Again, we should move this to a different thread to continue. This has nothing to do with Bell's Theorem or Christian's work.

 

[mbd]

Actually, DrChinese, the papers you mention very much confirm my viewpoint.

Firstly, both, at the outset, confirm that a loophole-free test has not been performed.

Second, the Sciarrino paper aims to address the issue of determining whether coincident detections really are associated with coincident emissions. This is exactly the issue I raised about inputs/outputs in my posting!

Third, the Zeilinger paper refers to the goal of closing of all MAJOR loopholes in one experiment, not the closure of ALL loopholes in one experiment. And, the experiment presented just rules out one class of local realist theories in a loophole free test, not all classes of theories.

In other words, there is nothing incorrect or outside the mainstream in my post. I am simply making an effort to explain why this question has been open since 1935, even though a few fervent non-localists seem to think it's closed.

So, DrChinese, can you please state in a form without ambiguity the definition of realism to which you've been referring? A quote from a paper would be fine too. The first two papers you referred the forum to as definitive on "realism" don't actually define realism at all, so a reference to a paper that does would be most helpful.

 

[mbd]

DrChinese, here is a paper to which I was directed by a member of the editorial board of a major physics journal because it is an example of how "non-locality" is far from being a prevailing viewpoint. And, it defines realism as I do (on page 3).

http://arxiv.org/abs/1108.0001

 

[DrChinese]

So, DrChinese, can you please state in a form without ambiguity the definition of realism to which you've been referring? A quote from a paper would be fine too. The first two papers you referred the forum to as definitive on "realism" don't actually define realism at all, so a reference to a paper that does would be most helpful.

EPR, 1935, as I keep telling you.

"If, without in any way disturbing a system, we can predict with certainty (i.e., with probability equal to unity) the value of a physical quantity, then there exists an element of physical reality corresponding to this physical quantity. It seems to us that this criterion, while far from exhausting all possible ways of recognizing a physical reality, at least provides us with one such way, whenever the conditions set down in it occur."

Then...

"Indeed, one would not arrive at our conclusion if one insisted that two or more physical quantities can be regarded as simultaneous elements of reality only when they can be simultaneously measured or predicted. On this point of view, since either one or the other, but not both simultaneously, of the quantities P and Q can be predicted, they are not simultaneously real. This makes the reality of P and Q depend upon the process of measurement carried out on the first system in any way. No reasonable definition of reality could be expected to permit this."

This is generally accepted as "realism". As I say, you are free to define as you like. It just won't match up to the definition used by most. Bell didn't even bother to mention it as a definition assuming that EPR covered it and that his audience would read and understand that 1935 paper.

And you keep mentioning your viewpoint and mentioning papers which "confirm" that viewpoint. We are not here to listen to individual viewpoints. I have mine too! The idea is to learn something about physics. In that regard, a moderated forum insures we stay on track and share things which those following the thread will find useful. You keep pulling the thread away from Christian's work and towards ideas you have (such as your post #213 preceding). If you want to discuss the definition of realism as it relates to QM, I again recommend you start a thread on it. I will gladly discuss it with you there. I am familiar with the author's work you cite and would be happy to comment.

 

[mbd]

DrChinese, Einstein correctly describes his condition as "sufficient, but not necessary", and you seem to have missed that point and are using it to mean "necessary and sufficient".

These subtleties go to the heart of the issue and why this is an open question in physics.

Further, please stop mischaracterizing my posts. You do not have nearly as deep an understanding of this material as you seem to think and, as a result, you are pushing a viewpoint that is seriously misleading with respect to the state of the science.

 

[DrChinese]

You do not have nearly as deep an understanding of this material as you seem to think and, as a result, you are pushing a viewpoint that is seriously misleading with respect to the state of the science.

I am hurt.

 

[DrChinese]

DrChinese, Einstein correctly describes his condition as "sufficient, but not necessary", and you seem to have missed that point and are using it to mean "necessary and sufficient".

Spoken like a person with a penchant for semantics.

 

[mbd]

Spoken like a person with a penchant for semantics.

Einstein qualifies his criterion (note, it is not a definition) by saying "Regarded not as a necessary, but merely as a sufficient, condition of reality, this criterion is in agreement with classical as well as quantum-mechanical ideas of reality."

The distinction is essential, not semantic.

According to Einstein's criterion, if a system meets it, then it is realistic. If a system does not meet the condition, Einstein's criterion is silent as to whether the system is realistic or not.

Here's one system that will help clarify the point:

Consider a pot of water, and let the maxim "a watched pot never boils" be true.* We can, at any time, "measure" the system to see if the system is boiling or not boiling. Now, try to measure the system to determine when it starts boiling. You cannot, at least not with arbitrary precision.

But, clearly, there is physical reality to the event that is the instant it starts boiling. Right? We can in fact predict quite precisely when the event occurs, but we cannot observe it. In fact, we can predict it without disturbing the system just as Einstein's criterion requires but we cannot directly observe the event.

As for simultaneous reality, assume identical pots A, B. We can, at any instant, measure A and know if B is boiling or not at that very instant. Note, though, we can only do this once and, unless A is boiling, the answer is valid only at that instant.

Now, let the two pots be slightly different and ask, which boils first? There is physical reality to this, there is an answer, and we can predict the answer. But, we cannot, through only the measurement "is the pot boiling or not?" answer this question.

This illuminates both why a precise definition of reality is essential and why it is essential to know what you are actually measuring or observing.

*We can, in fact, construct a pot that, when watched, does not boil if watching requires lifting of the lid and when not covered the heat loss matches or exceeds the heat input from the burner.

 

[DrChinese]

Einstein qualifies his criterion (note, it is not a definition) by saying "Regarded not as a necessary, but merely as a sufficient, condition of reality, this criterion is in agreement with classical as well as quantum-mechanical ideas of reality."

The distinction is essential, not semantic.

According to Einstein's criterion, if a system meets it, then it is realistic. If a system does not meet the condition, Einstein's criterion is silent as to whether the system is realistic or not.

Glad to know it is a criterion and not a definition. LOL.

EPR is a local realist's defense. EPR define "local realism"* by marrying 2 assumptions to the "elements of reality" criterion. We can show sufficiently (LOL) that elements of reality exist for photon polarization (as our example) at angles 0, 120, 240 (same as -120). This is experimentally verifiable and has never been much in question**. They ASSUME that the following are true (see last few paragraphs of EPR):

1. There are no FTL influences (i.e. no spooky action at a distance).
2. The individual physical quantities are considered to be simultaneous elements of reality. Otherwise, they state for the local realist position, reality here is dependent on the nature of a measurement there, and that would be unreasonable.

Bell showed that there are no datasets for angle settings 0/120/240*** which also match the QM (and classical optics) predictions: cos^2(theta) in the case of photons. IF you consider the EPR criterion of element of reality to have been SUFFICIENTly satisfied for 0/120/240 (not much to quibble about that); AND you accept that experiments support the cos^2 relationship QM predicts****, THEN either 1. or 2. (or both) are unwarranted assumptions. QED.

So: There is one criterion, and 2 assumptions put forth by EPR. Aspect et al plus hundreds more have demonstrated that the QM predictions are accurate. What DON'T you agree with that EPR says?

* The phrase is never used as such.
** Of course post-Bell local realists question everything, including the definition of "is".
*** Bell does not use these angles specifically, they are just one set of many possible. Makes no difference how many as long as there is one.
**** Notice that there is no need to simultaneouly measure 3 of anything to see this relationship. This is lost on Christian and many other writers. This has been experimentally verified to well over 30 standard deviations.

 

[Mathematech]

post-Bell realists most definitely question the signficance of postulate 2 and what it really has to do with philosophical realism, because it amounts to saying that reality is screwy if your lap or fist disappears.

 

[mbd]

post-Bell realists most definitely question the signficance of postulate 2 and what it really has to do with philosophical realism, because it amounts to saying that reality is screwy if your lap or fist disappears.

Exactly! And what about that instant of transition when a person is neither standing nor has a lap? The threshold event, that is? What if the directionality of that transition is what makes the detector click?

In any case, there are three classes of physicists: local realists, non-localists, and scientists.

Regarding a loophole-free experiment, in particular a photon experiment with the detection loophole closed, it can be definitive if and only if there are no unproven assumptions behind exactly what it is that's being detected.

 

[DrChinese]

Regarding a loophole-free experiment, in particular a photon experiment with the detection loophole closed, it can be definitive if and only if there are no unproven assumptions behind exactly what it is that's being detected.

The only experimental question is whether the quantum mechanical prediction of cos^2(theta) - and other similar predictions for other things that can be entangled other than polarization - matches nature. If you assert there is a loophole, you are saying that cos^2(theta) is flat out wrong, that the true rate is actually at least 33% instead of 25%. Those really aren't even close to the same value.

I don't think you realize what a jump you are making, but hey, that's your call. I have yet to understand why local realists assert a loophole in this one experiment, yet gleefully accept the results of all other scientific experiments. Do you accept the age of the universe as 13.7 billion years? What about the speed of light as about 300,000 km/sec? I guess you reject those too, there no more proof of those than of the QM predictions.

So let's summarize: All experiments support QM over the wildly different local realistic prediction. All loopholes have been closed individually. And does any of this overwhelming evidence change the mind of a single local realist? Not in my experience, no.

 

[mbd]

So let's summarize: All experiments support QM over the wildly different local realistic prediction. All loopholes have been closed individually. And does any of this overwhelming evidence change the mind of a single local realist? Not in my experience, no.

Well, if there is "spooky action at a distance", then I suppose it's plausible that you could have the results of the loophole-free experiment before it's been performed.

Heck, maybe there are aliens who, though light years away, are a couple years ahead of us in physics, they just performed the loophole-free experiment, and it just so happens that your result box is entangled with their result box!

 

[OCR]

The threshold event, that is? What if the directionality of that transition is what makes the detector click?

Well... that sure would be a quantum [STRIKE]waste[/STRIKE] waist ... lol



OCR

 

[mbd]

Well... that sure would be a quantum [STRIKE]waste[/STRIKE] waist ... lol
OCR

I think there's a "your mama" joke involving a non-local pair of pants ...

 

[OCR]

I think there's a "your mama" joke involving a non-local pair of pants ...

Lol...



OCR...

 

[DrChinese]

Well, if there is "spooky action at a distance", then I suppose it's plausible that you could have the results of the loophole-free experiment before it's been performed.

Heck, maybe there are aliens who, though light years away, are a couple years ahead of us in physics, they just performed the loophole-free experiment, and it just so happens that your result box is entangled with their result box!

You laugh, but not only is this possible, the experiment has already been performed. You can perform Bell tests, detect the photons, and see the results BEFORE the particles are entangled.

Experimental Nonlocality Proof of Quantum Teleportation and Entanglement Swapping
Thomas Jennewein, Gregor Weihs, Jian-Wei Pan, Anton Zeilinger
http://arxiv.org/abs/quant-ph/0201134

And you can entangle particles that have never even existed at the same time.

Entanglement Between Photons that have Never Coexisted
E. Megidish, A. Halevy, T. Shacham, T. Dvir, L. Dovrat, H. S. Eisenberg
http://arxiv.org/abs/1209.4191

These results are part and parcel of orthodox QM (although their realization is unorthodox). However, they are difficult to explain using hidden variables.

Keep in mind that I choose to retain locality and reject realism in the interpretation I subscribe to. This is fully in keeping with the Bell result. I can do this by accepting that observed results are context dependent (observer dependent) and I reject the potential existence of counterfactual outcomes. All of this is well within normal QM. So for me, a context includes future variables and the locations of those variables are restricted by c. This does give the appearance of being non-local, and that is what is referred to as quantum non-locality. This is different than the Bohmian view of non-locality.

 

[morrobay]

Keep in mind that I choose to retain locality and reject realism in the interpretation I subscribe to. This is fully in keeping with the Bell result. I can do this by accepting that observed results are context dependent (observer dependent) and I reject the potential existence of counterfactual outcomes. All of this is well within normal QM. So for me, a context includes future variables and the locations of those variables are restricted by c. This does give the appearance of being non-local, and that is what is referred to as quantum non-locality. This is different than the Bohmian view of non-locality.

When you say observer dependent do you mean that measurement not only disturbs what is being measured but produces it ? Also can you elaborate how the location of a variable, in context, in the future can be determined ? Maybe it is time for a thread on realism because it is becoming a very flexible term.

 

[DrChinese]

When you say observer dependent do you mean that measurement not only disturbs what is being measured but produces it ? Also can you elaborate how the location of a variable, in context, in the future can be determined ? Maybe it is time for a thread on realism because it is becoming a very flexible term.

Good idea! I will start one in a bit.

 

[audioloop]

post-Bell realists most definitely question the signficance of postulate 2 and what it really has to do with philosophical realism, because it amounts to saying that reality is screwy if your lap or fist disappears.

right and creates a logical contradiction.

 

[Mathematech]

I finally got round to reading Khrennikov's paper http://arxiv.org/abs/1108.0001 where he argues that "realism" is the culprit. He shows that a "non-realist" local model can produce quantum probabilities for single particles (actually he does a lot of hand waving but its good enough). He also argues that since we already can explain single particle quantum behaviour by rejecting realism, we obviously need to reject realsm also for entangled particles and since this is sufficient to escape Bell there is no justification for assuming nonlocality. In fact he makes the claim that both non-realism and non-locality is unlikely. I disagree with him on this point. As I've said before non-realism is sufficient to explain why QM correlations do not match Bell but it does not seem to be sufficient to explain the actual correlations obtained instead. He would need to demonstrate that the actual QM correlations obtained for entangled particles can be produced by a local non-realist model.

 

[bohm2]

He would need to demonstrate that the actual QM correlations obtained for entangled particles can be produced by a local non-realist model.

What is the difference between a local vs non-local non-realist model? I mean, if something is non-real, what would the difference be between the local vs non-local version? It's not as if there is any ontological difference between the two? I can't even make sense of non-realism, to be honest. I wish someone could explain it to me as I feel totally clueless despite reading a lot on the topic. If there's no "reality" apart from our conceptions of it, why even bother talking about "local" non-reality. It's not as if it would make any difference if we distingush the local type of non-reality vs the non-local type of non-reality? Gisin makes this point in his paper:

In conclusion, the claim that the observation of a violation of a Bell inequality leads to an alleged alternative between nonlocality and non-realism is annoying because of the vagueness of the second term.

Non-realism: Deep Thought or a soft Option
http://arxiv.org/pdf/0901.4255v2.pdf

Maudlin makes a similar argument with respect to Bohr's position:

The microscopic world, Bohr assured us, is at least unanschaulich (unvisualizable) or even non-existent. Unvisualizable we can deal with—a 10-dimensional space with compactified dimensions is, I suppose, unvisualizable but still clearly describable. Non-existent is a different matter. If the subatomic world is non-existent, then there is no ontological work to be done at all, since there is nothing to describe. Bohr sometimes sounds like this: there is a classical world, a world of laboratory equipment and middle-sized dry goods, but it is not composed of atoms or electrons or anything at all. All of the mathematical machinery that seems to be about atoms and electrons is just part of an uninterpreted apparatus designed to predict correlations among the behaviors of the classical objects. I take it that no one pretends anymore to understand this sort of gobbledegook, but a generation of physicists raised on it might well be inclined to consider a theory adequately understood if it provides a predictive apparatus for macroscopic events, and does not require that the apparatus itself be comprehensible in any way.

If one takes this attitude, then the problem I have been trying to present will seem trivial. For there is a simple algorithm for associating certain clumped up wavefunctions with experimental situations: simply pretend that the wavefunction is defined on a configuration space, and pretend that there are atoms in a configuration, and read off the pretend configuration where the wavefunction is clumped up, and associate this with the state of the laboratory equipment in the obvious way. If there are no microscopic objects from which macroscopic objects are composed, then as long as the method works, there is nothing more to say. Needless to say, no one interested in the ontology of the world (such as a many-worlds theorist) can take this sort of instrumentalist approach.

Can the world be only wavefunction?
In Ch. 4 of "Many Worlds?: Everett, Quantum Theory, and Reality"

 

[Maui]

Non realism does not necessarily mean that atoms don't exist between measurements, but that they exist in multiple states at once. When a measurement is performed, all associated behavior is found to obey locality. That's what i make of it, though admittedly i also don't understand(nobody does?) what kind of classical world would behave like this. People seem to be confusing philosophical realism and quantum realism and that seems to annoy quite a lot of physicists. At an ontological level, there is no consistent picture behind this proposal, nothing at all. But science as far as i am able to see hasn't moved past 'reality is best described by fields', so it is hardly surprizing that no one can visualize anything about the world quantum mechanically.
Becuase the quantum world is contextual and all events take place within the context of a measurement apparatus and its environment, physicists have grown accustomed to thinking of the world as that which is happening and all else is considered philosophical baggage. And since qm calls for a revision of realism, the best a physicist can do in such a mess is to retain locality so that physics doesn't become a conspiratorial magician's performance (the unobservable hidden variables).

 

[DrChinese]

Non realism does not necessarily mean that atoms don't exist between measurements, but that they exist in multiple states at once. When a measurement is performed, all associated behavior is found to obey locality. That's what i make of it, though admittedly i also don't understand(nobody does?) what kind of classical world would behave like this. People seem to be confusing philosophical realism and quantum realism and that seems to annoy quite a lot of physicists. At an ontological level, there is no consistent picture behind this proposal, nothing at all. But science as far as i am able to see hasn't moved past 'reality is best described by fields', so it is hardly surprizing that no one can visualize anything about the world quantum mechanically.

Good points.

Although we have (hopefully) left discussion of the OP behind, I would like to add a comment about non-realism. Non-realism can take a variety of forms. The above is one. Another is seen in MWI, because our reality is not exclusive. Another is seen in time-symmetric interpretations. In those, causes are not required to precede effects. Which is a tacit assumption in most formulations of realism.

 

[bohm2]

Non realism does not necessarily mean that atoms don't exist between measurements, but that they exist in multiple states at once.

Would that be non-realism? Wouldn't that just be the MWI, which is a "realistic" interpretation?

 

[Mathematech]

Realism in Bell/EPR discussions amounts to "counterfactual definiteness". Counterfactual definiteness means being able to meaningfully speak of values of observables that weren't measured but would have been obtained had they been measured. One might add, even in the case where an incompatible observable was measured instead.

Now this is still vague. "Meaningfully speak of" needs to be clarified and what it means for Bell discussions is that such values that would have been obtained (but weren't) can be treated on a par with actual obtained values when doing statistical calculations. (One might add, even for statistical calculations as simple as tallying.) This at first sounds like a completely reasonable assumption until one realizes that its more or less saying that even though pigs can't fly we can average in a supposed pig flying speed together with actual measured flying speeds of doves and swallows and expect our calculations to still produce reproducible averages :)

 

[ajw1]

Although we have (hopefully) left discussion of the OP behind...

As the article Joy Christian is referring to was mentioned earlier here this thread wouldn't be complete without mentioning Christian's response (that would be unfair sampling ;)): http://arxiv.org/pdf/1301.1653.pdf

 

[Maui]

Quote by Maui

Non realism does not necessarily mean that atoms don't exist between measurements, but that they exist in multiple states at once.

Would that be non-realism? Wouldn't that just be the MWI, which is a "realistic" interpretation?

This is a different scenario. In the first, we are discussing 1 world only, so with respect to this one world, prior to observation the states aren't real, since they don't belong to the observed classical reality.

In the latter case, the states can be said to be real(defined as having fixed properties) that belong to the relevant world when an interaction is performed.

But anyone can play this interpretational mumbo jumbo. The only reason it is accepted here, as with all other interpretations, is because of the rank of the author - Everett, Bohr, Bohm, T'Hooft, etc. If it weren't for the status of author, these 'interpretations' would have been right there with the "What the beep do we know?". So if we imagine that there are infinitely many worlds, our unreal states suddenly become real in a sense. But let's keep the assumptions minimal, even if doing so implies change.

 

[Mathematech]

I just read Gisin's paper "Non-realism: Deep Thought or a soft Option" (http://arxiv.org/pdf/0901.4255v2.pdf). He doesn't seem to be aware of the interpretation of "realism" as meaning counterfactual definiteness and doesn't even discuss it. He misses entirely the fact that the probability distributions in his equation 1 are not well defined in the face of non-counterfactual definiteness.

 

[DrChinese]

I just read Gisin's paper "Non-realism: Deep Thought or a soft Option" (http://arxiv.org/pdf/0901.4255v2.pdf). He doesn't seem to be aware of the interpretation of "realism" as meaning counterfactual definiteness and doesn't even discuss it. He misses entirely the fact that the probability distributions in his equation 1 are not well defined in the face of non-counterfactual definiteness.

I have to admit that his argument seems more oriented towards reaching the desired conclusion than allowing for a fuller definition of "non-realism". For example: EPR defines realism as the simultaneous existence of (unlimited) elements of reality. So non-realism would be the denial of that. As you say, that makes things contextual; there are only a few simultaneous elements of reality for any system. What is "annoying" or "vague" about that (using his terms)?

 

[bohm2]

I just read Gisin's paper "Non-realism: Deep Thought or a soft Option" (http://arxiv.org/pdf/0901.4255v2.pdf). He doesn't seem to be aware of the interpretation of "realism" as meaning counterfactual definiteness and doesn't even discuss it. He misses entirely the fact that the probability distributions in his equation 1 are not well defined in the face of non-counterfactual definiteness.

You might want to look at the updated published version of that paper (see below). In the first footnote this is how Gisin defines "realism":

My personal definition of realism—that clearly has not been falsified—is another issue. For me realism means, very briefly, that physical systems possesses properties preexisting and independent of whether we measure the system or not; however these preexisting properties do not determine measurement outcomes, but only their propensities. Accordingly, there are realistic random events that reflect preexisting properties, as required by realism, simply the reflection is not deterministic.

http://www.gap-optique.unige.ch/wiki/_media/publications:bib:nonrealismfinal.pdf

I have trouble completely understanding what he means by this, to be honest.

 

[Mathematech]

I have trouble completely understanding what he means by this, to be honest.

Yeah I read that sentence and decided I needed another cup of coffee before attempting it again :D

I'm also half way through Joy Christians rebuttal http://arxiv.org/pdf/1301.1653.pdf and so far all I see is a lot of unconscious redefining of how probability works with lots of Clifford algebra thingies ("multivectors") sitting in equations that have the shape of actual statistical calculations but which otherwise have no justification because they aren't really statistical calculations.

We would need some reason for entangled particles to follow Clifford algebra based statistical mechanisms like this instead of normal statistics which is back to square one as this Clifford stuff is really just the usual tensor product Hibert space QM stats in a different notation. In the same way that the usual tensor product stuff appears to be implying some sort of non-local connection, so too is this mathematically equivalent Clifford algebra stuff.

 

[Mathematech]

Ok I read Gisin's definition again and it seems that he is also unaware of that the propensity approach he is advocating ends up producing the same statistics as a deterministic approach (one of Arthur Fine's results) - this is all discussed for example in Redhead's book https://www.amazon.com/dp/0198249373/?tag=pfamazon01-20

 

[Mathematech]

FYI: Arthur Fine's paper http://www.citeulike.org/user/egcavalcanti/article/6011736 where he shows that going for models that conform to what Gisin seems to be saying his personal definition of realism is, are in fact no more general than a local hidden variable theory.

 

[Mathematech]

Further subtle points about Fine's result http://www.jstor.org/stable/187655

 

[bohm2]

Yeah I read that sentence and decided I needed another cup of coffee before attempting it again

Gisin's definition of "realism" kind of reminds me of the epigenetic modifications of the genome by environment, except for the non-locality.

 

[Mathematech]

Actually after completing Joy Christians latest paper I'm not convinced the math is correct, its seemingly based on a Clifford Algebra model of what the tensor product Hilbert Space formalism is saying but also contains some dodgey limits. Either its just plain wrong or if fixable at most just copies what the standard formalism already tells us without adding any real explanantion - why should the stats conform to the Clifford algebra based pseudo-statistics based on a parallelized hypersphere ... if there isn't some non-local mechanism enforcing it?

 

[Avodyne]

I haven't gone through this whole thread, so this paper by Richard Gill may have already been cited: http://arxiv.org/abs/1203.1504

IMO, this paper is a completely convincing demonstration that Christian's claims about Bell are vacuous.

Christian has a reply paper, which IMO is as vacuous as his previous ones. Find it yourself if you care to.

 

[jtbell]

Yes, Gill's article has been discussed in this thread, beginning here:

https://www.physicsforums.com/showthread.php?p=3804759#post3804759

In fact, Gill himself chimed in:

https://www.physicsforums.com/showthread.php?p=3812865#post3812865