Joy Christian, "Disproof of Bell's Theorem"


by bcrowell
Tags: bell's theorem
DrChinese
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Jan20-13, 07:22 PM
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Quote Quote by Maui View Post
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
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Jan20-13, 09:26 PM
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Quote Quote by Maui View Post
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
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Jan21-13, 01:28 AM
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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 realises 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 :)
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Jan21-13, 01:36 AM
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Quote Quote by DrChinese View Post
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
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Jan21-13, 11:05 AM
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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.
Quote Quote by bohm2 View Post
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
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Feb1-13, 05:31 PM
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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
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Feb1-13, 06:47 PM
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Quote Quote by Mathematech View Post
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
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Feb1-13, 08:40 PM
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Quote Quote by Mathematech View Post
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 possess 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...alismfinal.pdf

I have trouble completely understanding what he means by this, to be honest.
Mathematech
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Feb2-13, 01:27 AM
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Quote Quote by bohm2 View Post
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
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Feb2-13, 01:50 AM
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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 http://www.amazon.com/Incompleteness.../dp/0198249373
Mathematech
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Feb2-13, 04:24 AM
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FYI: Arthur Fine's paper http://www.citeulike.org/user/egcava...rticle/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
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Feb2-13, 06:50 AM
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Further subtle points about Fine's result http://www.jstor.org/stable/187655
bohm2
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Feb3-13, 10:00 PM
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Quote Quote by Mathematech View Post
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
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Feb6-13, 05:00 AM
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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
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Feb8-13, 12:49 AM
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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
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Feb8-13, 10:22 AM
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Yes, Gill's article has been discussed in this thread, beginning here:

http://www.physicsforums.com/showthr...59#post3804759

In fact, Gill himself chimed in:

http://www.physicsforums.com/showthr...65#post3812865
Avodyne
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Feb8-13, 11:40 AM
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But it seems not everyone is convinced.
bohm2
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Quote Quote by gill1109 View Post
Why should probability not ontologically exist? What kind of prejudice is that? I think quantum mechanics is telling us that it does exist, despite our intuition or instinct to the contrary. Our brains evolved and led us from success to success by hard-wiring in us a belief that nothing happens without a cause... this belief worked just fine, till we ran up against quantum mechanics.
Interesting comment since such a paper was recently published that kind of argues this:
We argue using simple models that all successful practical uses of probabilities originate in quantum fluctuations in the microscopic physical world around us, often propagated to macroscopic scales. Thus we claim there is no physically verified fully classical theory of probability. We comment on the general implications of this view, and specifically question the application of classical probability theory to cosmology in cases where key questions are known to have no quantum answer.
Origin of probabilities and their application to the multiverse
http://arxiv.org/pdf/1212.0953v1.pdf
Also discussed here:
Does Probability Come from Quantum Physics?
http://www.sciencedaily.com/releases...0205151450.htm


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