## Curtains for locality in QM?

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### Re: Curtains for locality in QM?

I'm hoping we can bring back minkwe's great Delft thread now (pruned if needed), and we can continue our exciting discussion of mutual information in EPR and anomalies in the experiments. Some great stuff in there.

Happy Halloween!

### Re: Curtains for locality in QM?

local wrote:You are now the third poster to demonstrate this. Congratulations, Richard!

Always happy to oblige!

### Re: Curtains for locality in QM?

You are now the third poster to demonstrate this. Congratulations, Richard!

### Re: Curtains for locality in QM?

local wrote:The local models minkwe and I gave were for the purpose of showing that it is possible to have random outcomes together with anticorrelation. They were not intended as local models of QM. Since you continue to misrepresent what I have said, you have confirmed your poor understanding of QM, and you notify us that you have time only for smatterings, I'm going to withdraw from this thread. Thank you for the stimulating discussion. Looking forward to your peer-reviewed publications!

Here is a model with random outcomes and anticorrelation. Let the hidden variable $\lambda =+/-1$ be a fair coin toss. Define the measurement functions $A$ and $B$ by $A({\bf a}, \lambda): = \lambda$ and $B({\bf b}, \lambda): = - \lambda$.

### Re: Curtains for locality in QM?

The local models minkwe and I gave were for the purpose of showing that it is possible to have random outcomes together with anticorrelation. They were not intended as local models of QM. Since you continue to misrepresent what I have said, you have confirmed your poor understanding of QM, and you notify us that you have time only for smatterings, I'm going to withdraw from this thread. Thank you for the stimulating discussion. Looking forward to your peer-reviewed publications!

### Re: Curtains for locality in QM?

local wrote:That didn't last long.

I always reserve the right to respond to provocative responses.
I don't object to anything in standard QM. I never offered any local model of QM.

Huh? This from your post viewtopic.php?f=6&t=411&start=20#p10297
You are repeating the assertion that minkwe and I already refuted with our local models.

Care to reconcile that with your above claim?
And if you will review this thread you'll see that I was the one who educated you about singlet rotational invariance.

I suggested otherwise? Go read again what I actually wrote. You read things the wrong way.

### Re: Curtains for locality in QM?

I'm giving this a rest

That didn't last long.

I don't object to anything in standard QM. I never offered any local model of QM. And if you will review this thread you'll see that I was the one who educated you about singlet rotational invariance.

As I said, I'll wait for you to demonstrate proper understanding of QM before further engaging with you. Do things the right way -- try to publish your ideas. If you prefer to just declare victory and move on, go for it!

### Re: Curtains for locality in QM?

local wrote:
Q-reeus wrote: Pedantic much?

Not at all. I'm just interested in Quantum Mechanics and not Q-reeus Mechanics.

the formal mathematical nature of QM is so non-intuitive for me and so riddled with a host of competing interpretations, I'm giving this a rest. Stepped into a minefield.

Gracious of you to admit your deficiencies. Perhaps when you have mastered the basics of QM, we can re-engage.

Uh huh. Why engage without also answering my last fielded questions (plural)? And re your local theory, which I have not looked at (only have time & interest to look at a small smattering of posts here in general), which aspects of standard QM do you reject? For instance, the isotropic nature of singlet state in standard QM, is that incorporated in your local theory?

### Re: Curtains for locality in QM?

Q-reeus wrote: Pedantic much?

Not at all. I'm just interested in Quantum Mechanics and not Q-reeus Mechanics.

the formal mathematical nature of QM is so non-intuitive for me and so riddled with a host of competing interpretations, I'm giving this a rest. Stepped into a minefield.

Gracious of you to admit your deficiencies. Perhaps when you have mastered the basics of QM, we can re-engage.

### Re: Curtains for locality in QM?

gill1109 wrote:
Q-reeus wrote:Not familiar with Luder's rule. I'll stick with above simple argument - local detector-particle random interactions should give purely local random results thus no joint correlations IF QM is truly local in nature.

Von Neumann's projection postulate says that the state collapses to one of an eigen-basis of the operator. If the spectrum is degenerate, then the postulate is not well defined, because it does not say how to choose a basis of each eigenspace corresponding to each distinct eigenvalue.

Lüders projection postulate says it collapses to its projection onto one of the eigenspaces.

Nowadays people just call it the Lüders-von Neumann postulate because von Neumann's was not adequate anywaay, when you have a degenerate spectrum. https://www.researchgate.net/publication/2200428_The_Lueders_Postulate_and_the_Distinguishability_of_Observables

Thanks for that reference Richard. For a local realistic theory like Joy's and where randomness originates in the state preparation not appreciably the detection process, then nonzero joint measurement correlations at least has an internal consistency to it. The price to pay say a curvy twisty S^3/S^7 space that evidently effects Bell type experiments and little or nothing else seems way too ad hoc to accept.

If on the other hand randomness of individual measurement outcomes originates exclusively or at least also in the detection process, it's illogical to claim that can be consistent with nonzero correlations while also local and realistic. Abandoning realism smacks too much of magic for me, so it's the imo lesser evil of locality that must give way.

I suppose there is a third or even more basic options - indivisibility of the entire system not permitting anything beyond shut up and calculate statistical outcomes.
Unlike say GR the formal mathematical nature of QM is so non-intuitive for me and so riddled with a host of competing interpretations, I'm giving this a rest.
Stepped into a minefield.

### Re: Curtains for locality in QM?

Q-reeus wrote:Not familiar with Luder's rule. I'll stick with above simple argument - local detector-particle random interactions should give purely local random results thus no joint correlations IF QM is truly local in nature.

Von Neumann's projection postulate says that the state collapses to one of an eigen-basis of the operator. If the spectrum is degenerate, then the postulate is not well defined, because it does not say how to choose a basis of each eigenspace corresponding to each distinct eigenvalue.

Lüders projection postulate says it collapses to its projection onto one of the eigenspaces.

Nowadays people just call it the Lüders-von Neumann postulate because von Neumann's was not adequate anywaay, when you have a degenerate spectrum. https://www.researchgate.net/publication/2200428_The_Lueders_Postulate_and_the_Distinguishability_of_Observables

### Re: Curtains for locality in QM?

local wrote:
Q-reeus wrote:incident particle spin orientations

There is no such thing according to QM. You are back to Q-reeus Mechanics.

Pedantic much? One particular spin state from a superposition is selected/projected out to yield an up/down measurement. Randomly at each detector.
Q-reeus wrote: Not familiar with Luder's rule. I'll stick with above simple argument - local detector-particle random interactions should give purely local random results thus no joint correlations IF QM is truly local in nature.

You should get familiar with it as it is crucial to properly understanding EPRB. It's baffling that with a poor grounding in QM you choose to opine on things in this experts forum. Do your homework!

You are repeating the assertion that minkwe and I already refuted with our local models. They give what you call purely random detection results but nevertheless show the desired anticorrelation. You haven't proven "local detector-particle random interactions". You are just asserting them, and it is not QM. Earlier you scolded me for talking about the particles, and you said the only reality is the singlet state, and now you are back to particle interactions!? Again, this is not QM. Nothing you say has any bearing on "curtains for locality in QM".

If your local theory(s) predicts both random measurements at each detector and anti-correlations for joint measurements then you have smuggled in non-locality somehow.
Going back to this para:
In case you were not aware of it, Luders' rule is a postulate, and postulating it for detection stations arbitrarily separated in space in effect postulates nonlocality (while also violating Lorentz invariance). If basic von Neumann projection is applied to EPRB instead of Luders' rule, as it should be, quantum correlations are not predicted. And that is why no experiment without disqualifying problems has ever demonstrated quantum correlation.

Then I take it you don't believe correlations are real but an artifact of improper maths? So your local model is simply intended to demonstrate that?
How will you react if as seems assured, 'quantum supremacy' is unambiguously demonstrated by e.g. Google researchers in the next month or so?
I have hardly looked at any of your other postings at SPF btw.

### Re: Curtains for locality in QM?

Q-reeus wrote:incident particle spin orientations

There is no such thing according to QM. You are back to Q-reeus Mechanics.

Q-reeus wrote: Not familiar with Luder's rule. I'll stick with above simple argument - local detector-particle random interactions should give purely local random results thus no joint correlations IF QM is truly local in nature.

You should get familiar with it as it is crucial to properly understanding EPRB. It's baffling that with a poor grounding in QM you choose to opine on things in this experts forum. Do your homework!

You are repeating the assertion that minkwe and I already refuted with our local models. They give what you call purely random detection results but nevertheless show the desired anticorrelation. You haven't proven "local detector-particle random interactions". You are just asserting them, and it is not QM. Earlier you scolded me for talking about the particles, and you said the only reality is the singlet state, and now you are back to particle interactions!? Again, this is not QM. Nothing you say has any bearing on "curtains for locality in QM".

### Re: Curtains for locality in QM?

local wrote:First, it cannot be both 0 or 180 degrees for anticorrelation. Only 0 degrees gives you that according to QM. Second, your assertion of inconsistency has already been refuted by the local model both minkwe and I presented to you.

A simple slip-up you keenly noticed and pounced on. So I should have wrote "...anti-correlation (correlation), for detector relative orientations of 0 (180 degrees)...
In keeping with my earlier posts btw.
It seems to me that now that you have abandoned the silly youtube video as well as your incorrect interpretation of QM, you are now just left standing there pushing all the standard Bell-based arguments for nonlocality. Is there anything new you have to add to that debate? If not, do you concede that it is not in fact "curtains for locality in QM"?

Even more so than earlier, given total indeterminancy of incident particle spin orientations, and logically purely local detector-particle angular momentum exchanges, how can overall singlet conservation of angular momentum have any bearing on measurement outcomes? Inherently random, local interactions should rule the roost. The joint measurements should be totally uncorrelated, if there is no 'mysterious' non-local entanglement connection - which standard QM predicts.
Well we all agree there is perfect joint measurement anti-correlations (correlations) for detector angles as previously prescribed. A physically plausible explanation, not purely mathematical concoction, is called for imo. How do you reconcile these factors in favor of QM locality?
In case you were not aware of it, Luders' rule is a postulate, and postulating it for detection stations arbitrarily separated in space in effect postulates nonlocality (while also violating Lorentz invariance). If basic von Neumann projection is applied to EPRB instead of Luders' rule, as it should be, quantum correlations are not predicted. And that is why no experiment without disqualifying problems has ever demonstrated quantum correlation.

https://arxiv.org/abs/1607.01808

I neither credit nor discredit the view that 3-sphere topology justifies application of Luders' rule, thereby allowing nature to exhibit quantum correlations. It is a separate debate and is not settled, so it cannot be appealed to in support of the idea of "curtains for locality".

Not familiar with Luder's rule. I'll stick with above simple argument - local detector-particle random interactions should give purely local random results thus no joint correlations IF QM is truly local in nature.

### Re: Curtains for locality in QM?

Q-reeus wrote: Yes having found other sources pointing out the inherent spherical symmetry of the singlet state implies impossibility of preparing an oriented state, will have to concede I backed the wrong horse in Derek.

Gracious of you to acknowledge it. However, I think you'll find no other good horses for proving quantum nonlocality.

Hence actual perfect anti-correlation for detector relative orientations of 0 or 180 degrees is still inconsistent with locality

First (minor point), it cannot be both 0 or 180 degrees for anticorrelation. Only 0 degrees gives you that according to QM. Second, your assertion of inconsistency has already been refuted by the local model both minkwe and I presented to you.

It seems to me that now that you have abandoned the youtube video as well as your incorrect interpretation of QM, you are just left standing there pushing all the standard Bell-based arguments for nonlocality. Is there anything new you have to add to the nonlocality debate? If not, do you concede that it is not in fact "curtains for locality in QM"?

In case you were not aware of it, Luders' rule is a postulate, and postulating it for detection stations arbitrarily separated in space in effect postulates nonlocality (while also violating Lorentz invariance). If basic von Neumann projection is applied to EPRB instead of Luders' rule, as it should be, quantum correlations are not predicted. And that is why no experiment without disqualifying problems has ever demonstrated quantum correlation.

https://arxiv.org/abs/1607.01808

We should also bear in mind the interesting view that 3-sphere topology justifies application of Luders' rule, thereby allowing nature to exhibit quantum correlations in some physical scenarios. That is a separate discussion and is not settled, so it cannot be appealed to in support of the idea of "curtains for locality in QM". Unless I am wrong, Dr Christian believes that quantum nonlocality is a mistake.

### Re: Curtains for locality in QM?

local wrote:No. As I said the singlet state does not have any axial orientation. It's very basic QM; I'm surprised you don't know this. The singlet state is rotationally invariant, so how can it have a defined axial orientation? See problem 1 here:

http://inst.eecs.berkeley.edu/~cs191/fa ... 1sol07.pdf

Assigning a spin axis to a singlet amounts to adding a "hidden variable" that is outside QM.

You have overstated my reliance on his presentation. I think it credible but, never said it was Gospel Truth. Go read my initial post again - and stop creating more straw men.

I'll just say that if you cannot find a decisive experiment, and this Derek chap can't cite one for you, then it would be reasonable to conclude that such an experiment does not exist.

Yes having found other sources pointing out the inherent spherical symmetry of the singlet state implies impossibility of preparing an oriented state, will have to concede I backed the wrong horse in Derek.
Even so, purely local detector-particle angular momenta exchanges, yielding 50:50 probability of up/down spin measurements at each detector, should wipe out any influence of 'global' conservation of angular momentum for the singlet particle pair. If QM obeys locality that is. Hence actual perfect anti-correlation for detector relative orientations of 0 or 180 degrees is still inconsistent with locality (I will avoid including 'reality').

### Re: Curtains for locality in QM?

Q-reeus wrote: Are you claiming singlet states can only be prepared with purely random axial orientations?

No. As I said the singlet state does not have any axial orientation. It's very basic QM; I'm surprised you don't know this. The singlet state is rotationally invariant, so how can it have a defined axial orientation? See problem 1 here:

http://inst.eecs.berkeley.edu/~cs191/fa ... 1sol07.pdf

Assigning a spin axis to a singlet amounts to adding a "hidden variable" that is outside QM.

You have overstated my reliance on his presentation. I think it credible but, never said it was Gospel Truth. Go read my initial post again - and stop creating more straw men.

I'll just say that if you cannot find a decisive experiment, and this Derek chap can't cite one for you, then it would be reasonable to conclude that such an experiment does not exist.

### Re: Curtains for locality in QM?

local wrote:You talked about orthogonality between the singlet and the detectors. There is no spin axis for a singlet according to QM, so your position is incoherent. You are transmuting Quantum Mechanics to Q-reeus Mechanics.

Are you claiming singlet states can only be prepared with purely random axial orientations?
I suggest that you get over your fixation on Derek Muller.

You have overstated my reliance on his presentation. I think it credible but, never said it was Gospel Truth. Go read my initial post again - and stop creating more straw men.

### Re: Curtains for locality in QM?

Q-reeus wrote: As per that vid, it's the common spin axis of a singlet pair that is polarized

You talked about orthogonality between the singlet and the detectors. There is no spin axis for a singlet according to QM, so your position is incoherent. You are transmuting Quantum Mechanics to Q-reeus Mechanics.

I suggest that you get over your fixation on Derek Muller.

### Re: Curtains for locality in QM?

local wrote:...Yes, it is hard to grasp. Asserting that you have an orthogonal relationship between a detector and an incident spin is incoherent because QM does assign spins to the particles in a singlet. Thinking of these particles as having some fixed spin is incorrect according to quantum mechanics. That's what the singlet state is all about.

Straw man. I never claimed individual spins had definite values prior to measurement. As per that vid, it's the common spin axis of a singlet pair that is polarized, with individual spins in a superposition of spin up and spin down along that common axis, prior to measurement. Hence the randomness of individual measurements.
Additionally, minkwe and I have both now asked you to cite the decisive experiment that you claim supports your position. Will you answer?

Already said I haven't found one yet. Maybe you or Minkwe or whoever else here might have better luck extracting such info from Derek Muller. I tried.

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