Bell Experinents / Non Locality of QM

[Alan Grayson]

Aren't these results an affirmation of the instantaneous collapse of the wf? AG

[Alan Grayson]

On Sunday, December 28, 2025 at 1:32:44 AM UTC-7 Alan Grayson wrote:

Aren't these results an affirmation of the instantaneous collapse of the wf? AG

How would Bell results be interpreted using the MWI? The results seem easy to interpret under Copenhagen. AG 

[Alan Grayson]

I still don't get it. If there's no collapse under the MWI, when UP is measured in THIS WORLD, how does the OTHER WORLD know to measure DN, ignoring the obvious fact that DN is ALSO measured in THIS WORLD?  AG

[Alan Grayson]

UP and DN are both measured in THIS WORLD. What I don't get is how adding the observer to the original superposition essentially forces the correct pair of ALICE-BOB 

measurements without any action at a distance when the pair are causally disconnected. AG

[Alan Grayson]

Assuming Bell experiments imply the non-existence of local hidden variables, which I believe is the general consensus, we can imagine Alice and Bob having synchronized clocks, and we can measure when each measures some spin, UP or DN. If we agree that spin angular momentum is conserved, then no matter how close their measurements are to simultaneity, spin angular momentum is conserved, and in the limiting case where their measurements are simultaneous, if Alice measures UP (or DN), then Bob must measure DN (or UP). Consequently, I don't see how we can avoid the conclusion of some instantaneous "influence" occurring.  Not faster than lightspeed, but instantaneous. Nor do I see any way the MWI circumvents this conclusion. AG

[Alan Grayson]

My subjective judgment is tha the MWI is too ugly to be true. But why can't we do what we normally do with competing theories; do measurements to distinguish them? Now, with super accurate atomic clocks, ISTM that we could synchorize the two clocks, of Alice and Bob, and separate their locations substantially, and determine if entangled particles created equidistant, are detected instantly by both parties. I would bet on Copenhagen. Any comments about the design of this experiment? AG

[Brent Meeker]

They each get some result and when they compare them they find they are correlated. Here’s the setup using photons. A pair of photons whose polarizations are entangled are created by down-conversion in a crystal and are sent to (possibly distant) polarizers and detectors.



The detectors record 0 (didn’t pass the polarizer) or 1 (did pass the polarizer). Alice and Bob keep records of the 0’s and 1’s and the angle settings in order so that later when they bring their records together they can calculate the correlation for each angle setting. For a Bell experiment, they do this for different runs with their polarizers set at angles 22.5deg and 45deg apart.

Note that in relativity there is no invariant meaning to “at the exact simultaneous time” at different places. They can be at the same time in one reference frame, but then they are not at exactly the same time in a different, moving, reference frame. The experiment only requires that the measurement events be space-like separate, i.e. no signal can travel between Alice and Bob so that the polarizer setting chosen by Alice influences the photon at Bob’s polarizer and vice versa. Bell’s theorem is that under the assumption of no-signaling between Alice and Bob a certain combination of the correlations must always be less than 2. Alain Aspect (and the other two Nobel recipients this year, Zeilinger, and Clauser) performed experimental tests of Bell’s theorem and showed it was violated over a certain range of angles.



The measurements are not made at zero relative angle, so measuring pass or didn't-pass is not the same at each detector.  Rather they are related probabilistically as shown.

Brent

[John Clark]

On Sun, Jan 4, 2026 at 7:20 AM Alan Grayson <agrays...@gmail.com> wrote:

> How would Bell results be interpreted using the MWI?

You've asked that question before and I have given a detailed response before, in fact I've done so more than once, but I am not going to do it again.  

 

> The results seem easy to interpret under Copenhagen. AG 

Even among themselves Copenhagen fans can't agree on what Copenhagen is saying, except perhaps that the best course of action is to just "shut up and calculate".   

> Assuming Bell experiments imply the non-existence of local hidden variables, which I believe is the general consensus,

No! As I've said before, the experimental fact that Bell's Inequality is violated proves that REALISTIC local hidden variables cannot exist in a DETERMINISTIC universe. Or to put it more simply, our commonsense ideas about how the world works cannot be correct. 

John K Clark

 

[Alan Grayson]

On Monday, January 5, 2026 at 4:20:30 AM UTC-7 John Clark wrote:

On Sun, Jan 4, 2026 at 7:20 AM Alan Grayson <agrays...@gmail.com> wrote:

> How would Bell results be interpreted using the MWI?

You've asked that question before and I have given a detailed response before, in fact I've done so more than once, but I am not going to do it again.  

 

> The results seem easy to interpret under Copenhagen. AG 

Even among themselves Copenhagen fans can't agree on what Copenhagen is saying, except perhaps that the best course of action is to just "shut up and calculate".  

Copenhagen is a non-local theory because of the collapse hypothesis, that effects can occur instantaneously. By simplying it into a slogan only adds to the confusion. Seems unrelated to Bell experiments. OTOH, the MWI denies non-locality via the Many Worlds it hypothesizes. Again, unrelated to Bell experiments. AG 

> Assuming Bell experiments imply the non-existence of local hidden variables, which I believe is the general consensus,

No! As I've said before, the experimental fact that Bell's Inequality is violated proves that REALISTIC local hidden variables cannot exist in a DETERMINISTIC universe. Or to put it more simply, our commonsense ideas about how the world works cannot be correct. 

How did you get to the DETERMISTIC? AG 

John K Clark

 

[Alan Grayson]

On Monday, January 5, 2026 at 4:20:30 AM UTC-7 John Clark wrote:

That's an implication of what I wrote, and to which you responded. So I don't think "No!" is an appropriate response. AG 

 

John K Clark

Generally speaking,  the core error of the MWI is the false claim that it's based solely on S's equation. But that equation is based on the frequentist approach to probability. No where does it assert or imply that all outcomes MUST exist, and thus the existence of Many Worlds. AG

 

[Alan Grayson]

Assuming everything you've written above is correct, can you succinctly explain why it implies local hidden variables don't exist? AG 

[John Clark]

On Tue, Jan 6, 2026 at 5:21 AM Alan Grayson <agrays...@gmail.com> wrote:

>  can you succinctly explain why it implies local hidden variables don't exist? AG 

As I keep telling you, local hidden variables CAN exist, BUT NOT IF THINGS ARE REALISTIC AND DETERMINISTIC, you can't have all three. That's why the experimental finding that Bell's Inequality is violated has not ruled out objective collapse (my second favorite quantum interpretation), it's local and realistic but not deterministic, so Bell has not ruled it out. Many Worlds (my favorite) is local and deterministic but not realistic, so Bell has not ruled that out. Pilot Wave is realistic and deterministic but not local, so Bell has not ruled that out. As for Copenhagen, there is no consensus of what the hell it's saying so there is no consensus on whether Bell has ruled that out or not. And "shut up and calculate" has not been ruled out because it refuses to play the game. What has definitely been ruled out is our common sense ideas about how the world should work.  

  John K Clark    See what's on my new list at  Extropolis

w36

[Alan Grayson]

Physicists agree with my statement, that Bell experiments show that local hidden variables do not exist. I am not clear how you reached your conclusion. Of course, if reality is realistic as Einstein thought, then hidden variables would exist, since in this case they're not hidden. Isn't the point of Bell experiments to show whether E's claim of realism is true? How could "objective collapse" be local? Isn't what you call objective collapse the Copenhagen interpretation? AG 

[Brent Meeker]

The function of correlations between of angles formed by Bell decreases linearly from 2 to -2 and never exceeds 2, yet the experimental result does exceed 2 at 22.5deg intervals between a, b', a', and b.

Brent

[Alan Grayson]

I can see that from the plot. But what I can't do is connect that plot to the claimed result that local hidden variables don't exist. AG 

[Brent Meeker]

Bell's result is a proof that that a correlation due to a shared hidden variable cannot produce a value greater than 2 for the function he cites.

Brent