Register to reply

Joy Christian, Disproof of Bell's Theorem

by bcrowell
Tags: bell's theorem
Share this thread:
mbd
#199
Dec27-12, 01:12 PM
P: 53
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
Nugatory
#200
Dec27-12, 01:16 PM
Mentor
P: 3,929
Quote Quote by mbd View Post
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://ajp.aapt.org/resource/1/ajpia...sAuthorized=no
Behind a paywall, unfortunately. Can you summarize the distinction as Blaylock sees it?
mbd
#201
Dec27-12, 01:22 PM
P: 53
Quote Quote by Nugatory View Post
Behind a paywall, unfortunately. Can you summarize the distinction as Blaylock sees it?
http://arxiv.org/abs/0902.3827
Maui
#202
Dec27-12, 03:09 PM
P: 724
Quote Quote by mbd View Post
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
#203
Dec27-12, 03:32 PM
P: 53
Quote Quote by Maui View Post
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
#204
Dec27-12, 03:54 PM
Sci Advisor
PF Gold
DrChinese's Avatar
P: 5,441
Quote Quote by mbd View Post
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
#205
Dec27-12, 04:56 PM
Mentor
P: 3,929
Quote Quote by Maui View Post
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
#206
Dec27-12, 05:04 PM
P: 53
Quote Quote by DrChinese View Post
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
#207
Dec27-12, 06:26 PM
Sci Advisor
PF Gold
DrChinese's Avatar
P: 5,441
Quote Quote by mbd View Post
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
#208
Dec28-12, 10:14 AM
P: 461
the definition of realism/reality goes beyond physics.
Nugatory
#209
Dec28-12, 10:57 AM
Mentor
P: 3,929
Quote Quote by audioloop View Post
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
#210
Dec28-12, 11:18 AM
P: 741
Quote Quote by audioloop View Post
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
#211
Dec28-12, 02:43 PM
P: 53
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
#212
Dec28-12, 03:36 PM
Sci Advisor
PF Gold
DrChinese's Avatar
P: 5,441
Quote Quote by mbd View Post
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
#213
Dec28-12, 06:47 PM
P: 53
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
#214
Dec28-12, 08:54 PM
P: 53
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
#215
Dec29-12, 11:15 AM
Sci Advisor
PF Gold
DrChinese's Avatar
P: 5,441
Quote Quote by mbd View Post
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
#216
Dec29-12, 12:50 PM
P: 53
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.


Register to reply

Related Discussions
Joy Christian's disproof of Bell Quantum Physics 70
Bell's Theorem and Counterfactual Definiteness Quantum Physics 5
Christian Science General Discussion 1
Why is the Wikipedia article about Bell's spaceship paradox disputed at all? Special & General Relativity 109