The Impact of Weak Realism on Bell's Theorem and Bohmian Interpretations

[Ilja]

1. Don't get this, you are essentially saying Norsen should be considered more of an authority than Zeilinger? Zeilinger is one of the pre-eminient authorities in the area, and entanglement is his specialty. Certainly this is relevant.

He is a good experimenter, but I don't value his theoretical considerations. The issue we are talking about is a theoretical, almost philosophical. In this domain, Zeilinger is no authority for me.

Norsen is primarily a theorist as best I know, although I thought he was doing some experimental work more recently. I would certainly like to see something from him that delved into some new areas more at the forefront of the field, as Zeilinger is doing.

If your position is that experimenters are more on some imaginary "forefront" than theoreticians, I disagree.

Now anyone can be wrong, and anyone can be right, regardless of their prior background. But what we are discussing is not the outcome of an experiment, but rather the relevance of that outcome. So certainly, we *should* consider the opinion of the scientific community in this case.

The point is that the opinion of the scientific community has been referenced by Norsen and there is no disagreement about this opinion. Thus, for the discussion of Norsen's arguments against this opinion the facts about this opinion are irrelevant.

Also: Travis frequently interprets sections of standard texts and comes up with his own views on their meaning and context - against standard opinion. OK, sometimes that can be good too. But he often ignores any text or argument which goes against his opinion. Example: Norsen says EPR is about locality and not realism. Yet EPR references locality only ONCE, versus over a dozen times for realism.

This is something I would count as "minor objections". The word-count of "realism" and "locality" in the EPR paper is clearly not relevant for any interesting philosophical or physical question.

He never addresses this obvious flaw in his reasoning. In addition, EPR provides the standard definition of realism ("elements of reality").

Yet Norsen seeks his own definition, changing the character of the paper in the process. It has been my hope to learn if there is any "meat" to Travis' argument that I am missing in his work. Thus, I was hoping you could enlighten me on this in some fashion. If the best anyone can do is quote Norsen over EPR, quote Norsen over Bell, and quote Norsen over Zeilinger, given the huge gaps I have just mentioned... well, that fails on every level.

I don't consider Norsen as a historian of science and have not evaluated if historical claims in his paper are correct. The argumentation he gives about realism is what interests me. And these arguments are quite nice.

2. I'm laughing... There are plenty who believe that a Bohmian interpretation is deterministic and therefore realistic. And additionally ruled out by contextual no-go proofs. I don't happen to fall in that camp. But clearly, there is something odd about asserting that a theory has hidden variables, is deterministic, and yet is also contextual. Essentially, that viewpoint agrees with the EPR conclusion that a more complete specification of the system IS possible. And I reject that.

Of course, a more complete specification is possible, and there is an explicit example of such a more complete specification, pilot wave theory.

About the reasoning "deterministic and therefore realistic" - hm, one can imagine superdeterministic theories, and I would not consider them as realistic in the EPR-Bell sense, because they do not give any realistic explanations. Thus, better omit the "therefore". Pilot wave theory is deterministic and realistic.

But that pilot wave theory is contextual is correct, it is simply a fact. There is no disagreement in the scientific community about it, as far as I know. Contextuality is not in conflict with common sense realism.

 

[p764rds]

excuse me if I am a little off the current dispute/argument)

Norsen's paper Quote:
"We have carefully surveyed Bell’s concept of local causality, emphasizing several points which are often misunderstood:
...
• A theory’s violation of the criterion means that it
posits non-local causation, not mere non-local correlations.
• A theory’s violation of the criterion does not necessarily" End Quote
from:
http://arxiv.org/PS_cache/arxiv/pdf/0707/0707.0401v1.pdf

My point is this:
As far as SR goes, then Lorentz Invariance must apply to strong causal phenomology. But this does not mean that weak causal structures such as entangled correlations need obey Lorentz. ALternatively (my personal preference) is that the so-called physical distance is not in fact a real distance but a metric - indentifiers for the particles (or indeed waves if QFT considered). So the particles are not actually separated as far as correlation of states is concerned at all - indeed IMO that is how they behave and why I said in an early post that I thought the correlation effect is instantaneous (or very nearly!) - and as experiment has shown too.
Particles not physically separated (only by a metric), is equivalent, to both having simultaneous access to the same 'correlation data'. (Don't forget a 'mechanism' is still helpful to explain correlation IMO)
Lorentz Invariance would not need to be invoked because there is no strong cause and effect violation with correlation.

 

[DrChinese]

1. If your position is that experimenters are more on some imaginary "forefront" than theoreticians, I disagree.

2. The point is that the opinion of the scientific community has been referenced by Norsen and there is no disagreement about this opinion. Thus, for the discussion of Norsen's arguments against this opinion the facts about this opinion are irrelevant.

3. This is something I would count as "minor objections". The word-count of "realism" and "locality" in the EPR paper is clearly not relevant for any interesting philosophical or physical question.

4. Of course, a more complete specification is possible, and there is an explicit example of such a more complete specification, pilot wave theory.

... But that pilot wave theory is contextual is correct, it is simply a fact. There is no disagreement in the scientific community about it, as far as I know.

1. If your opinion is that Norsen is more on some imaginary theoretical forefront than Zeilinger, I respectfully disagree. Perhaps you recall GHZ? I cannot comprehend how you could dismiss Zeilinger's theoretical work, which has opened important new areas. I am not trying to defend Zeilinger, but come on! Get your facts straight before you blow people off.

2. There is almost universal opinion that Norsen is wrong. Not sure your point here. What you were arguing a few posts back that numbers didn't matter, now you are claiming that Norsen is in the majority.

3. If the words of the author count for nothing, I guess I could claim that EPR is about tea leaves. My point, as always, is that EPR and Bell frame the conclusion, well documented, that:

No physical theory of local Hidden Variables can ever reproduce all of the predictions of Quantum Mechanics.

EPR set the stage, and you can see from Bell's title - "On the EPR Paradox" - what Bell's paper is about. And it is NOT about locality (as an assumption) alone.

4. Spoken in the words of a true believer. You might want to consider labeling your opinions next. There is a big difference between saying "a more complete specification is possible" and saying "it is possible to construct a candidate theory in which a more complete specification is possible". These are not the same at all, are they?

My summary: Norsen has missed the mark and overstepped in his conclusion. I welcome a reformulation of Bell which does not require realism a la EPR as a part of the proof. If Norsen would provide that, then he would have something of substance. Until then, I don't expect much to come from this piece except as references by others with the same opinion. If you have any new insights on Norsen's arguments, I welcome those. Otherwise, I will leave you to the last word on this subject.

 

[DrChinese]

excuse me if I am a little off the current dispute/argument)

Norsen's paper Quote:
"We have carefully surveyed Bell’s concept of local causality, emphasizing several points which are often misunderstood:
...
• A theory’s violation of the criterion means that it
posits non-local causation, not mere non-local correlations.
• A theory’s violation of the criterion does not necessarily" End Quote
from:
http://arxiv.org/PS_cache/arxiv/pdf/0707/0707.0401v1.pdf

My point is this:
As far as SR goes, then Lorentz Invariance must apply to strong causal phenomology. But this does not mean that weak causal structures such as entangled correlations need obey Lorentz. ALternatively (my personal preference) is that the so-called physical distance is not in fact a real distance but a metric - indentifiers for the particles (or indeed waves if QFT considered). So the particles are not actually separated as far as correlation of states is concerned at all - indeed IMO that is how they behave and why I said in an early post that I thought the correlation effect is instantaneous (or very nearly!) - and as experiment has shown too.
Particles not physically separated (only by a metric), is equivalent, to both having simultaneous access to the same 'correlation data'. (Don't forget a 'mechanism' is still helpful to explain correlation IMO)
Lorentz Invariance would not need to be invoked because there is no strong cause and effect violation with correlation.

I don't think it is clear either way that Lorentz invariance need apply to wave state collapse. In fact, as I understand Demystifier's position, there may or may not be preferred frames; and key elements of the theory might or might not be Lorentz Invariant. In other words, this is not a per se requirement of the pilot wave theory either way.

Personally, I try to picture that in 4D spacetime, 2 points may be separated. But in higher dimensions, perhaps there is a shorter path between those same 2 points. That would give a non-local character. Of course, that is just a mental picture. In other words, there could be a number of non-local mechanisms out there, and Demystifier is exploring those.

 

[Ilja]

1. If your opinion is that Norsen is more on some imaginary theoretical forefront than Zeilinger, I respectfully disagree. Perhaps you recall GHZ? I cannot comprehend how you could dismiss Zeilinger's theoretical work, which has opened important new areas. I am not trying to defend Zeilinger, but come on! Get your facts straight before you blow people off.

I simply state as a fact that Zeilinger is no authority for me, whatever his credentials. This is not a blow, because there are simply very few people I accept as authorities, but even these are not beyond critical examination and can loose this status easily for a single nonsensical claim.

But let's simply compare not people but arguments.

2. There is almost universal opinion that Norsen is wrong. Not sure your point here. What you were arguing a few posts back that numbers didn't matter, now you are claiming that Norsen is in the majority.

You have misunderstood me. Norsen has quoted opinions of the majority he disagrees with. This is certainly not a claim that Norsen is in majority, but that he has clarified the situation, and in particular the mainstream opinion about the question he is discussing. And this simply shows that you have no point if you quote the same majority which Norsen has already quoted.

3. If the words of the author count for nothing, I guess I could claim that EPR is about tea leaves. My point, as always, is that EPR and Bell frame the conclusion, well documented, that:

No physical theory of local Hidden Variables can ever reproduce all of the predictions of Quantum Mechanics.

EPR set the stage, and you can see from Bell's title - "On the EPR Paradox" - what Bell's paper is about. And it is NOT about locality (as an assumption) alone.

Let's repeat: Of course, EPR and Bell use other assumptions as well: classical logic, elementary probability theory, and also some minimal assumptions about realism and causality which are necessary to do science. These are assumptions which are implicitly used in almost every scientific paper and in this sense it is not necessary to mention them explicitly. One can as well omit realism from the list of explicit assumptions and put it into the standard list of implicit ones, and, reversely, put logic into the list of explicit assumptions. If one does this, one can show that local logic is incompatible with quantum theory, which is as meaningful and correct as to say the same about local realism. It would be even better, because there is only one logic, standard classical mathematical logic, thus, this does not invite confusion between minimal metaphysical EPR-Bell realism and plainly wrong naive realism.

I do not object that one makes these assumptions explicit, but Norsen clearly has a point here.

4. Spoken in the words of a true believer. You might want to consider labeling your opinions next. There is a big difference between saying "a more complete specification is possible" and saying "it is possible to construct a candidate theory in which a more complete specification is possible". These are not the same at all, are they?

In principle, yes, but in this case "a more complete specification is possible" becomes unprovable, because all we can do is to construct candidates for such a more complete specification. To prove that a given candidate is the true completion is impossible. Therefore, with "a more complete specification is possible" one usually means that such candidate theories can be constructed.

My summary: Norsen has missed the mark and overstepped in his conclusion. I welcome a reformulation of Bell which does not require realism a la EPR as a part of the proof. If Norsen would provide that, then he would have something of substance.

I summarize that you have simply not understood his point.

Until then, I don't expect much to come from this piece except as references by others with the same opinion. If you have any new insights on Norsen's arguments, I welcome those. Otherwise, I will leave you to the last word on this subject.

I don't claim to have any new insights, I simply have understood his point, which is a simple and valid one: Using "realism" without specification in the list of assumptions invites confusion between the extremely weak notion of EPR-Bell-realism, which cannot be given up in a reasonable way, and naive realism (or the requirement for non-contextuality), which is simply wrong. And to require realism to be mentioned in the list of assumptions is inconsistent, because then one has to mention equally well logic and probability theory.

About references by others: I already don't expect anything at all from the mainstream. The mainstream works in a "publish or perish" world with short time jobs where one has to follow the authorities to get published and to get future grants. For a mainstream scientist, alternative approaches are simply too dangerous. He has to care for future jobs and grants.