How can we test the holographic principle and nonlocality in quantum mechanics?

[ttn]

2. Your dismissal of the non-realist viewpoint smacks of a faith-based viewpoint - i.e. one outside of science. You believe in an absolute reality, and others see a relative reality.

More abuse of language. If believing in an external world is an act of "faith", then what, exactly, does the concept "faith" mean? What would be left that *isn't* an act of "faith"?

*I* think faith means (roughly): believing in something even though there is no evidence for it, you can't see it, etc. But reality (which is a collective term meaning "all the stuff we see all the time, and everything else there is, too") is directly available to our gaze at all times. Whenever you are awake and conscious, you're drowning in evidence that reality exists.

Or maybe you mean something special by the adjective "absolute"? If so, you'll have to explain what you mean. I'd be happy to say that, yes, reality is absolute, but it seems a pointless and unnecessary qualifier: reality just *is*.

3. You almost are required to quote Einstein in order to frame the debate. I use his definitions frequently in my writing too. Of course he would not associate himself with the non-realistic school. And of course, he would be even LESS likely to associate himself with the non-local school.

If he were alive today? There's no question he'd have been shocked and amazed by Bell's Theorem, but would understand and accept its implications. For sure, he'd give up locality before he'd give up realism. Only a crazy person would make the opposite choice, and Einstein was not crazy.

4. If it is self-refuting and obvious, why don't I see that?

No comment.

Why don't others, such as (insert lengthy list here) etc.

Because they're stupid and/or twisted and corrupted by crap philosophy.

Is everyone stupid except you?

No. I know lots of smart, clear-thinking people. I'm sure you can guess who some of them are, since I tend to quote their papers and refer to their articles and urge people to read their books (and that kind of thing) all the time. If you weren't taking notes before, here's a short list of smart people who aren't me: Einstein, Bohm, Bell, Shelly Goldstein, Tim Maudlin, David Albert, Rod Tumulka, Andrew Whitaker, Howard Wiseman, Jim Cushing, Antony Valentini, and of course many others.

Just for fun, here's a list of smart people who are me: me!

 

[DrChinese]

No comment.

Drat! I was throwing you a softball on that one... (Of course, you levelled some good ones against everyone else...)



I do think it is interesting that you are so certain that Einstein, had he known about Bell & Aspect, would choose realism over locality. I think the answer is less clear. I do not think he would have embraced "spooky action at a distance" easily, if at all.

 

[ttn]

Drat! I was throwing you a softball on that one... (Of course, you levelled some good ones against everyone else...)



I do think it is interesting that you are so certain that Einstein, had he known about Bell & Aspect, would choose realism over locality. I think the answer is less clear. I do not think he would have embraced "spooky action at a distance" easily, if at all.

That you find it interesting suggests to me that you still haven't grasped one of the main points here. There is really no choice between "giving up realism" and "giving up locality". Without reality, there is no such thing as locality. So to give up realism is to give up *both*. Hardly a cost-effective strategy. Which is all of course just another way of saying what I've been saying all along (and Bell said for many years before I was even born): you have to give up locality. That's just what the EPR/Bell Theorem(s) prove.

 

[christian_dude_27]

can i ask a simple question? are we still on topic here :D

cd

 

[DrChinese]

can i ask a simple question? are we still on topic here :D

cd

We are now... unless that was your question.

By the way, I think it is great that you want to get degrees in physics. You will learn ever more about this fascinating world we inhabit.

 

[RandallB]

can i ask a simple question? are we still on topic here

Since the TITLE of the thread is simply “Nonlocality” I’d say it is fair enough.

As to your OP looking for information - getting someone’s opinion along with it is unavoidable. The opportunity to explain or justify those opinions / facts often comes with it as well as you’ve seen. Not so much to promote their ideas as to defend them from not being considered which is fair enough.
But much of that debate is furtherer down the road for you.

To your point of what to read and how to learn; I too can only offer an opinion.

As to “The Holographic Universe” By Michael Talbot I must admit I haven’t given it a fair read but I don’t intend to – My quick impression of his approach was just much too mystical for me.

However, I do not have as much a problem with “The Dancing Wu Li Masters”.
You can find a good deal of basic info to understand the science itself there. Paradoxes, basics of the standard model, and a little hard to follow entanglement.
BUT BE WARNED – although it does a better job of segregating the Zen – Metaphysics Junk; it is often only separated by a new paragraph – IMO you need to identify that stuff and just skip it! Otherwise you wind up just accepting what is in essence a mystical view from the start.

I agree with your starting point of local vs. non-local, best revealed in entanglement, as a good starting point.
“Entanglement” by Aczel is good book to look at even if I don’t agree with most of his conclusions.
I’d also recommend clicking on DrC ’s public profile, look at his website on entanglement, and past posts on EPR-Bell Entanglement. You will find links and a lot different ideas in those threads. Don’t expect to find someone with THE answer, just understanding the problem is a big enough task.

To be fair what do I believe? – I’m convinced that were Einstein able to see the hard evidence ‘proving’ reality to be ‘non-local’ he would still say that it only shows we still don’t understand something. Making me very much a “Local Realist” endeavoring to justify that position. So I don’t think I’m in line with anyone here, i.e. well outside the mainstream, and you don’t need to deal with ideas like that starting out.

 

[nrqed]

That you find it interesting suggests to me that you still haven't grasped one of the main points here. There is really no choice between "giving up realism" and "giving up locality". Without reality, there is no such thing as locality. So to give up realism is to give up *both*. Hardly a cost-effective strategy. Which is all of course just another way of saying what I've been saying all along (and Bell said for many years before I was even born): you have to give up locality. That's just what the EPR/Bell Theorem(s) prove.

I have to admit that Iget easily lost in all those discussions because I don't know what most terms mean. So I really would not be able to take side with either ttn or Dr Chinese (or to create a third, incompatible point of view!). I will sure sound dumb but with all the terms thrown around, the discussion sounds to em a bit like this:

A: the work of Joe Blow implies that the patatoum is inconsistent with a point of view based on booliloomism

B: No! Booliloomism is in conflict with the principle of fillipoutap. There is no ontology of yamamum in booliloomism

A: this is ridiculous. You never understood that the patatoum is irrelevant to goulogog and therefore booliloomism can't be an epistemology of the principle of badagag.

B: That is absurd! everybody knows that goulogog is...

and so on


But I *know* that there is something very deep and interesting here so I would like to understand very much. To a level where I could understand the difference between Dr Chinese's point of view and ttn's. And agree with one or the other or disagree or decide to not commit.

But I am pretty sure nobody will have the patience to guide me through (it is probablymore fun to argue with knowledgeable people, even those who disagree completely, than to explain to a newbie).

But I will ask anyway...

To start, could someone explain what "realism" means??



Pat

 

[rewebster]

"There is no spoon"

 

[DrChinese]

“Entanglement” by Aczel is good book to look at even if I don’t agree with most of his conclusions.

I’d also recommend clicking on DrC ’s public profile, look at his website on entanglement, and past posts on EPR-Bell Entanglement. You will find links and a lot different ideas in those threads.

Why thanks! Here is the link to my page on Bell's Theorem, which should not present any controversial issues itself. It is intended as a starting point for those at any level.

Bell's Theorem: An Overview with Lotsa Links

I like the Aczel book as well, it has plenty of interesting historical background on many of the great minds of quantum physics.

 

[DrChinese]

To start, could someone explain what "realism" means??



Pat

In the context of EPR/Bell, realism means: a particle has simultaneous definite values for observable properties (such as the usually quoted properties: position and momentum). This should be a fairly innocuous definition.

At the risk of repeating what many already know:

QM's Heisenberg Uncertainty Principle (HUP) states that as position is measured with greater precision or definiteness, momentum becomes less certain and definite as to value (and vice versa). The HUP is usually considered to be experimentally verified.

So the question becomes: how do you reconcile realism (which says both are always definite) with the HUP (which says only one can be definite at a time)? Einstein felt that QM was not complete, the HUP represented an experimental barrier, and that realism must be true. (ttn also takes realism as an absolute, and usually you would not go too wrong siding with Einstein). However, numerous theoretical issues discovered in the past 50 years have tended to cast some degree of doubt on Einstein's position on realism. As of today, I do not believe this issue is generally considered as resolved one way or the other.

 

[RandallB]

To start, could someone explain what "realism" means??

Realism; I’ll take my best shot – not that all will agree with me.

Realism is the idea that even the smallest things, even photons, act and react much the same as, and follow similar rules as, things we see in everyday day life – real.
QM see things at the tiny level as being inherently probabilistic at the individual events, requiring a collection of problematic micro events that cannot be understood within “realism” but as they are collected to build a macro world - can be seen in that macro world act in what we understand very well as real.

Now BM likes to pose a solution that it defines as “real” BUT “Non-local” in a manor that is supposed to achieve two things.
1) Be understandable to our realism thinking minds
AND
2) complying with the same expectations being predicted by the HUP of QM.

But in integrating enough variable to allow the uncertainty of HUP is enough to define it as not real from a QM view especially since the approach produces no clear experimental ideas that could resolve the issue.

As a Local Realist myself, I have to make clear that my expectation of realism is one that demands “Local Variables” to rule; not superposition or some loose version of realism that matches the results of HUP, guide waves or whatever. Thus from my view I see BM and QM as essentially equivalent, so I am very much not in agreement with BM. Just as I’m not satisfied with the non-real more importantly non-local aspects of QM.
Based on current science I’d have to say my position is the weakest.

Does that help at all.

 

[ttn]

In the context of EPR/Bell, realism means: a particle has simultaneous definite values for observable properties (such as the usually quoted properties: position and momentum). This should be a fairly innocuous definition.

If *that's* what you mean by "realism" then we shouldn't be arguing about it. *This* "realism" (which most normal people just call "hidden variables") is *not* an assumption of the EPR-Bell argument. You can't save locality by denying this kind of realism.

To save locality, you have to deny a much deeper sort of realism -- perceptual realism or even metaphysical realism (which is what rovelli and the other "interactional" people jettison by getting rid of any notion of objective reality in favor of simply how things "are" in relation to all other possible observers/systems).

At the risk of repeating what many already know:

QM's Heisenberg Uncertainty Principle (HUP) states that as position is measured with greater precision or definiteness, momentum becomes less certain and definite as to value (and vice versa). The HUP is usually considered to be experimentally verified.

You're completely missing the point. All that's verified is that one can't simultaneously *know* the values of non-commuting properties. Everybody agrees about that. The question is: can such properties nevertheless *exist* (so that the qm description would be incomplete)?

But given that this thread is about non-locality, even that doesn't matter. Again, the EPR-Bell proof of nonlocality does not hinge on the completeness or incompleteness of QM.

 

[Tez]

[deleted my comments - suddenly realized why I stick to research instead of forums - its so much easier]

I will say (to Dr. Chinese and several others) that ttn, while I disagree with him about many things (particularly the attractiveness of Bohmian mechanics) is spot on in his understanding of Bells theorem and other related issues. You guys are very lucky to have him consistently sit here and argue with you all. At the first ever Special Focus Session on Quantum Foundations of the APS march meeting he came up specifically as someone who would be elected to a modern all-star team of deep thinkers about foundations of quantum mechanics - and there wasnt a SINGLE one of us on the completely unofficial and very biased panel who was a Bohmian, as he is. Please try and get out of the bad habit of thinking you know what he is saying and try to listen to what he is ACTUALLY saying...

ok, back to my unreal world of people as insane as I am...

 

[DrChinese]

[deleted my comments - suddenly realized why I stick to research instead of forums - its so much easier]

I will say (to Dr. Chinese and several others) that ttn, while I disagree with him about many things (particularly the attractiveness of Bohmian mechanics) is spot on in his understanding of Bells theorem and other related issues. You guys are very lucky to have him consistently sit here and argue with you all. At the first ever Special Focus Session on Quantum Foundations of the APS march meeting he came up specifically as someone who would be elected to a modern all-star team of deep thinkers about foundations of quantum mechanics - and there wasnt a SINGLE one of us on the completely unofficial and very biased panel who was a Bohmian, as he is. Please try and get out of the bad habit of thinking you know what he is saying and try to listen to what he is ACTUALLY saying...

Hi Tez! Always good to hear you weigh in. Anything in particular you think he is saying that I'm not hearing? (You were spot on in some advice you gave me a few months ago on multi-photon entanglement that really helped...)

 

[DrChinese]

The question is: can such properties nevertheless *exist* (so that the qm description would be incomplete)?

ttn,

1. I am not sure in what respect your definition is different than mine: "Realism = A particle has simultaneous definite values for observable properties (such as the usually quoted properties: position and momentum)" - and which you say is more commonly accepted as a definition of hidden variables. They seem pretty close to me. Or to quote Einstein, if you prefer: "I think that a particle must have a separate reality independent of the measurements. That is: an electron has spin, location and so forth even when it is not being measured." What am I missing?

2. Let me be more specific about what you mean when you ask "can such properties nevertheless exist". I have a photon, and I know I can measure its polarization with a suitable filter set at angle settings A, B or C individually. Is it your opinion that it has (or hypothetically would have) a specific definite value at all 3 angles simultaneously, even if we can know it only one at a certain point in time?

3. Is it your opinion, as a follower of BM, that perfect correlations in an EPR set-up are explained by a type of instantaneous communication between the entangled particles?

Thanks,

-DrC

 

[ttn]

1. I am not sure in what respect your definition is different than mine: "Realism = A particle has simultaneous definite values for observable properties (such as the usually quoted properties: position and momentum)" - and which you say is more commonly accepted as a definition of hidden variables. They seem pretty close to me.

That's fine. So let's just call them "hidden variables." Then what you're apparently still missing is that the EPR argument proves, under the assumption of locality, that these HV's must exist. Then Bell's Theorem and associated experiments proves that this kind of HV theory is inconsistent with experiment.

To recap: Locality implies X, but X is false.

If you conclude from that (only) that X is false, you are still missing the main point of what Bell did.

2. Let me be more specific about what you mean when you ask "can such properties nevertheless exist". I have a photon, and I know I can measure its polarization with a suitable filter set at angle settings A, B or C individually. Is it your opinion that it has (or hypothetically would have) a specific definite value at all 3 angles simultaneously, even if we can know it only one at a certain point in time?

No, I don't think it has these. But i think the EPR proof (or some modified version thereof) that LOCALITY REQUIRES THE PHOTON TO HAVE THESE PROPERTIES is valid.

People tend to drop logic 101 and be very sloppy when they think about this. "Einstein liked HV's, and Bell showed that this was inconsistent with experiment, so too bad for Einstein (and, usually, good for Bohr!." This is sloppy wrong thinking. Einstein believed in HV's because they were *required* by locality (and he believed in locality). Bell showed that what's *required* by locality, doesn't exist -- i.e., that locality is false.

Here's the million-dollar point: and you can't elude this conclusion by saying "well maybe there aren't HV's". No, even a theory without HV's has to be non-local to agree with experiment.

3. Is it your opinion, as a follower of BM, that perfect correlations in an EPR set-up are explained by a type of instantaneous communication between the entangled particles?

It's my opinion as an all-star understander of Bell that some superluminal causation maintains the Bell-inequality-violating correlations. If that's what you meant (by "communication" etc.) then, sure. Being a "follower of BM" (or not) has nothing to do with it. BM is merely one possible empirically viable theory. Being non-local isn't among its virtues -- we know that *all* empirically viable theories have to be non-local. So that isn't why I like it. That's just the price you have to pay in any theory to have a theory that actually works empirically. The actual virtues of Bohm's theory lie elsewhere, e.g., in its solution of the measurement problem, in its clear (and almost embarrassingly simple) explanation of the otherwise-paradoxical double slit experiment, etc.

Let me make one thing absolutely clear by saying it yet again: I do *not* think "nature is nonlocal" because Bohm's theory is nonlocal and I like Bohm's theory. It's just the other way around. Unlike other people, who reject Bohm's theory because it is nonlocal, I recognize *first* (independent of Bohm's theory) that nonlocality is required by the combined EPR and Bell theorems -- and then am willing to take the other virtues of Bohm seriously. In short: not "nonlocality because of Bohm", but "Bohm because of nonlocality."

 

[DrChinese]

1. No, I don't think it has these. But i think the EPR proof (or some modified version thereof) that LOCALITY REQUIRES THE PHOTON TO HAVE THESE PROPERTIES is valid.

2. It's my opinion as an all-star understander of Bell that some superluminal causation maintains the Bell-inequality-violating correlations. If that's what you meant (by "communication" etc.) then, sure... In short: not "nonlocality because of Bohm", but "Bohm because of nonlocality."

Thanks, your replies help me to understand your position a lot better.

1. EPR itself obviously never said: Locality -> HVs. But I can see how a suitably modified (or enhanced, whatever) version of EPR could be construed to come to this conclusion. After all, one of Einstein's comments was, in effect, that:

(HUP=Complete) -> Spooky action at a distance

Which in turn becomes:

No HVs -> Non-locality

Which, if true, implies its contra-negative is also true:

Locality -> HVs


2. This also makes some sense. And I can't deny that there are days I believe that there is in fact some kind of superluminal causation as you do.

But on other days I wake up and remind myself that I too (like you apparently) believe that there is "not simultaneous reality to non-commuting observables"; and I believe that statement is sufficient to explain Bell test results without discarding locality too.

 

[ttn]

But on other days I wake up and remind myself that I too (like you apparently) believe that there is "not simultaneous reality to non-commuting observables"; and I believe that statement is sufficient to explain Bell test results without discarding locality too.

Well then those "other days" are apparently the ones in which you forget about the EPR argument, which proves that locality *requires* "simultaneous reality to non-commuting observables" (i.e., local hidden variables which determine the outcomes of spin measurements).

It's really simple. Either you accept that there is a valid argument for this claim (locality --> hidden variables), or you don't. If the latter, I'm sure you can point out a flaw in quant-ph/0601205, which provides a rigorous proof for locality --> hidden variables. Or alternatively, as I have said soooooo many times, you could provide a counterexample (namely, a local theory which actually predicts perfect correlation and violation of Bell's inequalities).

 

[DrChinese]

Well then those "other days" are apparently the ones in which you forget about the EPR argument, which proves that locality *requires* "simultaneous reality to non-commuting observables" (i.e., local hidden variables which determine the outcomes of spin measurements).

It's really simple. Either you accept that there is a valid argument for this claim (locality --> hidden variables), or you don't. If the latter, I'm sure you can point out a flaw in quant-ph/0601205, which provides a rigorous proof for locality --> hidden variables. Or alternatively, as I have said soooooo many times, you could provide a counterexample (namely, a local theory which actually predicts perfect correlation and violation of Bell's inequalities).

I do not intend any disrespect. But we already know that your paper uses a definition of locality that is aligned with what you call "Bell Locality" and which is consistent with Bell's later ideas. On the other hand, EPR (and Einstein) use the term local in more of a relativistic sense - as do I and a lot of others. So that explains why some people do not accept your paper's contention that Bell test experiments demonstrate non-locality. (I would personally not call it a flaw in your paper.)

Therefore: I simply state: QM could be considered a local* theory which predicts results in complete accordance with Bell tests. This is the counter-example you asked for, and will suffice for anyone whose definition of locality matches mine (and Einstein's). It will not suffice for those whose definition matches yours (and Bell's), because you insist that QM is either not a local** theory or not a valid*** theory.

I know you do not agree with my thinking, but certainly you must be able to see why many would. Like you, I do not think the number of people who agree with a point of view is a measure of the validity of that point of view.

(*and also non-realistic, because there are no HVs - this of course violating your assertion that: locality -> HVs)

(** although it does not explicitly violate relativity)

(*** very difficult to accept this, as there is no known flaw in its predictions)

NOTE: The above was edited to conform to RandallB's criticism below - I did not word my earlier version very well - apologies.

 

[RandallB]

relativistic QM is a local* theory which predicts results in complete accordance with Bell tests. This is the counter-example ...a definition of locality matches mine (and Einstein's)...
... it must be local, by definition, precisely because it is relativistic)

Whoa hold up there DrC. You were doing fine till this one.

You’ve got Einstein agreeing with QM just by plastering on Relativistic to QM and calling it “LOCAL” just not realistic! How do you make that work?

The non-local part of QM comes from HUP and pasting on relativistic is not going to solve the correlations seen in entanglement except by retaining the non-local probabilistic solution of HUP.
Einstein would not accept this as a local solution, although I sure he would still be convinced that something is being missed even with current experiments and ‘proofs’, just as Von Newman’s proof did change his mind in his day.

Did not expect you to call QM in any form “local”,
I just don't see where that can cut it.

TNN already knows I disagree that there is anything to distinguish BM over QM or any other non-local theory (String, M, MWI, etc).
That includes the “measurement solution” shown in the Double Slit.
There QM defines a probabilistic ending location.
BM defines a definitive ending position based on a definite trajectory departing the slits. Unfortunately, the BM departing trajectory from the slits is unmeasured, likely un-measurable, and (oops) probabilistic, thus no real solution there anyway.

So from my ‘Local Realist’ view, I can not see anything but “Non-Local” assigned to QM or BM, with or without Relativity (or Einstein). The only advantage between the two being personal preference based on the application.

 

[DrChinese]

Whoa hold up there DrC. You were doing fine till this one.

You’ve got Einstein agreeing with QM just by plastering on Relativistic to QM and calling it “LOCAL” just not realistic! How do you make that work?

The non-local part of QM comes from HUP and pasting on relativistic is not going to solve the correlations seen in entanglement except by retaining the non-local probabilistic solution of HUP.

Einstein would not accept this as a local solution, although I sure he would still be convinced that something is being missed even with current experiments and ‘proofs’, just as Von Newman’s proof did change his mind in his day.

Did not expect you to call QM in any form “local”,
I just don't see where that can cut it.

TNN already knows I disagree that there is anything to distinguish BM over QM or any other non-local theory (String, M, MWI, etc).
That includes the “measurement solution” shown in the Double Slit.
There QM defines a probabilistic ending location.
BM defines a definitive ending position based on a definite trajectory departing the slits. Unfortunately, the BM departing trajectory from the slits is unmeasured, likely un-measurable, and (oops) probabilistic, thus no real solution there anyway.

So from my ‘Local Realist’ view, I can not see anything but “Non-Local” assigned to QM or BM, with or without Relativity (or Einstein). The only advantage between the two being personal preference based on the application.

Well, I guess that's a fair point. I have edited the post to better get across what I was trying to say (but obviously failed to accomplish, upon a later reading). So thanks for setting me straight.

If we want to look at it from the perspective of the debate as EPR framed it - and that's where I am really at - then using the term "relativistic" could be misleading. I think it is relativistic in the (limited) sense that there is nothing about it that directly conflicts with relativity's prohibition that causes/signals not propagate with a velocity > c. That was intended to contrast with BM, which is "grossly non-local" (I think this was Bell's phrasing) by pretty much any standards.

So do I think oQM/QFT local? I think it is in some ways per above. I think it isn't in other ways, some of which match ttn's (or Bell's) definition. When the answer depends on an EXACT and extremely precise definition of locality, then I think that different people will come to different conclusions. That is part of the reason I object to ttn's blanket description that "Bell tests -> non-locality".

I definitely see that Bell's Theorem incorporates assumptions of both realism (or HVs) and locality - despite ttn's denial of this (not trying to stir that argument up again, as we have already been down that road a few times). So while I am left wondering whether to dump realism or locality, he is adamant that locality must be dumped to account for the results. And I can certainly see some respects in which he is right, and other respects in which I think he is wrong. I don't see how he arrives at an absolute position on the matter.

 

[ttn]

I do not intend any disrespect.

None taken. But you're still not getting it, and everything I'm saying at this point has been said a thousand times before in previous posts. So this will be my last post on this thread, and I'll simply advise you to go back and re-read our exchanges from the past and try to (as Tez suggested) pay attention to what I'm *actually* saying, not what you think I ought to have said.

But we already know that your paper uses a definition of locality that is aligned with what you call "Bell Locality" and which is consistent with Bell's later ideas. On the other hand, EPR (and Einstein) use the term local in more of a relativistic sense - as do I and a lot of others.

That's a false dichotomy if I've ever heard one. We all mean the same thing by locality in a qualitative sense -- no superluminal action at a distance. The problem is, Einstein et al just talked loosely about "no superluminal causation" without ever making such a requirement mathematically precise. That is what "Bell Locality" accomplishes. Your comment seems to be based on a tacit assumption that Bell Locality is not just the requirement of no superluminal causation, but something else too (like maybe it smuggles in "realism" or "hidden variables" or "determinism" or some such). But that just ain't so.

Therefore: I simply state: relativistic QM is a local* theory which predicts results in complete accordance with Bell tests.

That's dumb. I could just as well say: "Therefore: I simply state: Bohmian Mechanics is a local theory which predicts results in complete accordance with Bell tests." See, wow, it's easy to just say stuff like that. The problem is, both of our assertions are false. Bohm's theory is *not* local (the nonlocality is right there in the dynamics for all to see). And same for your orthodox QM: the nonlocality is right there in the dynamics (viz, the collapse postulate) for all to see.

I assume what you mean by "relativistic QM" is N-particle Dirac theory, or QFT, or some such. The problem is, all such "relativistic" theories are only 50% relativistic: of the two dynamical formulas which define the theories, one is local (the unitary evolution equation) and one isn't (the collapse equation). So, misleading names to the contrary notwithstanding, such theories are *not actually consistent with relativity*.

So, sorry, but you have not provided a counterexample to my assertion.

This is the counter-example you asked for, and will suffice for anyone whose definition of locality matches mine (and Einstein's).

See about. But re: Einstein... you've got to be kidding! If you think Einstein would have been content with orthodox QM (that is, content as in willing to accept that the theory is local) you have (again) completely and totally failed to appreciate the point of EPR. The whole argument there is that we have to regard orthodox QM as providing an *incomplete* description of states *because otherwise the theory is manifestly nonlocal*.

Until you get this, you are just wasting your time trying to grasp Bell. Go back and read "The Shaky Game" or "Einstein's Boxes" or something again until you get it.

It will not suffice for those whose definition matches yours (and Bell's), because you insist that relativistic QM is either not a local** theory or not a valid*** theory.

I've never been ambiguous about this. Orthodox "relativistic" QM is not a local theory. It violates Bell Locality, plain and simple, and that means it includes superluminal causation. There is of course no mystery whatsoever about this: the theory just openly says that the state of one particle can change *instantaneously* as a result of a spacelike separated measurement.

I know you do not agree with my thinking, but certainly you must be able to see why many would.

Sure, it's because they have yet to appreciate Bell Locality as a correct mathematical transcription of "no superluminal causation". But that's their problem, not Bell's or mine.

(** yet it must be local, by definition, precisely because it is relativistic)

That's the weakest argument yet! I can take N-particle Dirac theory and write down a Bohmian version of it. The evolution equation for the N-particle wave function is manifestly covariant (it's the same equation in the orthodox and Bohm theories, of course). So let's call this "relativistic Bohm theory". Can I then infer that "relativistic Bohm theory" is local, by definition, precisely because it is relativistic? No. That would be wrong. The theory is actually non-local, because the *other* part of the dynamics (the Bohmian guidance formula) is manifestly *not* Lorentz invariant. It requires some preferred frame to define it. But guess what? The orthodox version of the same N-particle Dirac theory works exactly the same way: the unitary evolution equation for the wave function is Lorentz invariant, but *the other half of the dynamics isn't*.

(*** very difficult to accept this, as there is no known flaw in its predictions)

Yes, nobody questions that these theories all give the right empirical predictions. The *only* issue is whether or not they are local. I say: Bell Locality gives a clear mathematical criterion for deciding. You seem to say: if a theory's name has "relativistic" in the title, then it's local by definition.

I'll leave it to you and others to work out which makes more sense.

 

[DrChinese]

I say: Bell Locality gives a clear mathematical criterion for deciding. You seem to say: if a theory's name has "relativistic" in the title, then it's local by definition.

As I pointed out in response to RandallB, my post used poor wording. So my apology about that.

I agree that Bell Locality as you formulate it in mathematical terms is pretty clear. I do not agree that definition is required to prove Bell's Theorem. And even if it were, it does not remove the other critical assumption of Bell's Theorem: that of realism, which is essential to the theorem. Bell: "It follows that c is another unit vector [in addition to a and b] ...". Without this assumption* - that there are other settings at which the spin component is considered to be simultaneously real and well defined - there is no Bell's Theorem. You always skip this point in your rush to tell me I don't get it. Unless and until you address this key point head on, I don't expect your "Bell test results -> Locality" to be convincing.

 

[RandallB]

I simply state: QM could be considered a local* theory ...
(*and also non-realistic, because there are no HVs - this of course violating your assertion that: locality -> HVs)

Granted removing “relativistic” helps just a little but, DrC in think here is where a significant communications problem can develop based on different scientific vocabulary or nomenclature applied to various terms.

I refer to a confusion I’m seeing between “local” “non-realistic” and “reality”.
Consider the value of looking at these terms in this way.
Reality = An understanding of how the world and all that is in it truly works; a puzzle man has been working on since the ancient Greeks.
Realistic = Something that conforms to that Reality what ever it may be; Multi Dimensional, String, QM, BM whatever.
Non-realistic = Therefore means something that is an incorrect solution.
Thus Realistic and Non-realistic should not be defined by what we understand as our current level of “Common Sense” or Classical interpretation of what we see as a three dimensional world. That more Common understanding is better defined as:
Local = The idea that reality conforms to the requirements expressed in EPR where individual objects retain unique non-commuting variables – no weird action at a distance.
Non-Local = Those definitions of reality that allows for weird action at a distance as viewed from our common or classical perception within that overall reality.

I believe when you try to apply the term local to QM by allowing it to retain the element of “Non-Realistic” the only thing that is meaningful in that Non-realistic component is the probabilistic Non-Local part.
Taking the idea, "QM as local", into an impossible self-destructive circular logic.

Local and Non-Local is the more efficient way of breaking the possible forms of reality into two major categories. (basically Einstein vs. HUP)
What is “Realistic” is more of what we a looking for in what is the true reality. Presuming a view of what is realistic cannot be done without assuming an end solution of what is that true reality.

Does organizing these terms this way make sense and help?

 

[DrChinese]

Granted removing “relativistic” helps just a little but, DrC in think here is where a significant communications problem can develop based on different scientific vocabulary or nomenclature applied to various terms.

I refer to a confusion I’m seeing between “local” “non-realistic” and “reality”.
Consider the value of looking at these terms in this way.
Reality = An understanding of how the world and all that is in it truly works; a puzzle man has been working on since the ancient Greeks.
Realistic = Something that conforms to that Reality what ever it may be; Multi Dimensional, String, QM, BM whatever.
Non-realistic = Therefore means something that is an incorrect solution.
Thus Realistic and Non-realistic should not be defined by what we understand as our current level of “Common Sense” or Classical interpretation of what we see as a three dimensional world. That more Common understanding is better defined as:
Local = The idea that reality conforms to the requirements expressed in EPR where individual objects retain unique non-commuting variables – no weird action at a distance.
Non-Local = Those definitions of reality that allows for weird action at a distance as viewed from our common or classical perception within that overall reality.

I believe when you try to apply the term local to QM by allowing it to retain the element of “Non-Realistic” the only thing that is meaningful in that Non-realistic component is the probabilistic Non-Local part.
Taking the idea, "QM as local", into an impossible self-destructive circular logic.

Local and Non-Local is the more efficient way of breaking the possible forms of reality into two major categories. (basically Einstein vs. HUP)
What is “Realistic” is more of what we a looking for in what is the true reality. Presuming a view of what is realistic cannot be done without assuming an end solution of what is that true reality.

Does organizing these terms this way make sense and help?

I will grant you that it ends up being "something" and "non-something", but the usual categorizations are:

"Local vs. Non-local"
"Realistic vs. Non-realistic" or frequently "HV or No-HVs"

It is worthwhile to mention that the "No-HVs" scenario is often labeled as "No Go". No Go Theorems are those, such as The Kochen-Specker Theorem, basically say that particles do not have well-defined properties outside/independent of the context of an observation. There are a lot of No Go Theorems being posted into the arxivs.

Whereas: some theories state that entangled particles are able to communicate using a form of instantaneous communication or similar, that we are not otherwise aware of from experiments. And this is more along the lines of the non-local idea.

The problem with the "realistic" label is that is an ineffective word, that has a lot of baggage associated with it - at least for some. I like it fine but a lot of people don't.

 

[ttn]

You always skip this point in your rush to tell me I don't get it. Unless and until you address this key point head on, I don't expect your "Bell test results -> Locality" to be convincing.

I really don't have time to keep debating this, but I couldn't let this comment go. Here's my response: you've got to be f***ing kidding me.

I keep explaining, over and over and over and over again, that the EPR argument *from* locality *to* hidden variables (or what you sloppily insist on calling "realism") is the point you're missing here. I even wrote a whole long detailed paper (two, actually) explaining this point. That, after all this, you'd come back and say "yeah, but Bell assumed *both* locality *and* hidden variables, so can't we blame the violation of the inequalities on hidden variables?" tells me you're either stupid, pathologically forgetful (think "Memento"), or deliberately wasting my time. I mean, seriously, how the hell can you accuse me of not addressing this key point head on? It's the most outrageous accusation I've ever heard.

If you have any serious interest in understanding this stuff, and if you want to take Tez's good advice seriously, then you need to go back and re-read what I've said (sooooo many times here, and in papers) and try to actually *pay attention* and *remember* some of it. Or if, as I suspect, you are just an ignorant time-waster who is hell-bent on remaining such, you'll have to find someone else to argue with.

 

[DrChinese]

... you're either stupid, pathologically forgetful (think "Memento"), or deliberately wasting my time... Or if, as I suspect, you are just an ignorant time-waster who is hell-bent on remaining such, you'll have to find someone else to argue with.

I think the "Memento" one is probably closest...

Perhaps you are correct, and I am the only person out here that doesn't follow your line of thinking. I will continue to read what you write, and continue to look for that part of what you say that I can learn from. If you do or do not want to respond to my posts, that is strictly your choice.

 

[RandallB]

I still think you’re allowing yourself to get hung-up in a naming convention problem overlapping Layman vocabulary with a Scientific vocabulary with the resulting confusion and misunderstanding between terms/definitions that wind up driving some into a third colorful vocabulary.

The problem with the "realistic" label is that is an ineffective word, that has a lot of baggage associated with it - at least for some. I like it fine but a lot of people don't.

But here in this word is where I think you run into trouble, because in layman terms it means in effect EPR-Local – I happen to like the idea of EPR-Local. My Local Realist view would accept “realistic” in the layman sense of the word. Therefore, I would never use the term “realistic” as it implies HV-Locality is the true reality (the reality I believe in). But science has yet to completely define reality or we would have both a GUT & TOE to answerer these issues.

Therefore, I disagree with the term even being used in any theory KS, MWI, QM, BM any of them, because it implies some knowledge of the complete workings of true reality. And that is what we are looking for! You can not assume the solution to offer as proof of that solution.

I suspect if you take some time and focus on what you really mean by “realism” as you have used it, you will see it as simply another term for EPR-Local or ‘go’ HV.

BUT, if the intention is to describe “something” that can be Non-local or even can somehow contain both local and non-local ideas in ‘realism’; it needs to be defined in much better detail than I’ve seen.
AND, If so that “something” should be given a different name not realism.

 

[DrChinese]

I still think you’re allowing yourself to get hung-up in a naming convention problem overlapping Layman vocabulary with a Scientific vocabulary with the resulting confusion and misunderstanding between terms/definitions that wind up driving some into a third colorful vocabulary.

...

BUT, if the intention is to describe “something” that can be Non-local or even can somehow contain both local and non-local ideas in ‘realism’; it needs to be defined in much better detail than I’ve seen.
AND, If so that “something” should be given a different name not realism.

The short answer is: Bell's Theorem is usually cast to say that "Quantum Mechanics is incompatible with all Local Realistic theories" and "Bell test results support QM over LR". Then they say: "You must jettison the assumption of locality or realism, or both". This isn't really my words, it's just a common description and one does not need to agree that those words are the best description (or even accurate). It is simply the stock answer.

But the standard way of seeing the issue is that there are *2* separate assumptions embedded in Bell's Theorem: locality and realism (or HVs, or non-contextuality, or more complete description of the wave function, or observer independent reality, or whatever term you prefer). It is not common to express these as a single assumption. Although it may turn out that they are 2 sides to the same coin, I can't say. And ttn feels strongly that it is locality that must be jettisoned.

Look: when people first heard about relativity, many had a hard time picturing how there could NOT be an absolute reference frame. And similarly: when people hear that we may live in an observer dependent reality, many have a hard time picturing how that might be possible. So be it; I didn't invent it so please don't hold me personally responsible for it (as apparently ttn does). The collapse of an entangled wave function operates in a manner that is otherwise counter-intuitive, regardless of what you choose to toss.

 

[Ernies]

The voluble Dr. Chinese keeps saying "why do most people not agree...". I am a retired theoretical physicist who talked with Bell (and Feynmann, for that matter).
Most people used to agree with Von Neumann's 'theorem' showing the argument for non-local theories to be inconsistent till Bell (among others) destroyed it. "Not just stupid, but silly" was his comment. Yet the theorem's errors were pointed out by a Dutchman- whose name I have forgotten-- only a year after Neumann's paper. So for half a century or so 'most people' agreed with Neumann because of his reputation, and held up a lot of physics for that period. So much for 'most people'.
Bell knew what he meant, and what the inequality implied. All the kerfuffle ultimately depends on whether the effects are thought of as causal, or as is usual in QM dismissed as correlations.
I'm on the side of Bell's original interpretation. I cannot quote it exactly but it amounted to the choice between non-locality and science depending on 'observers'.

Ernies