Margenau's argument

Foundations of physics and/or philosophy of physics, and in particular, posts on unresolved or controversial issues

Re: Margenau's argument

Postby gill1109 » Sun Oct 18, 2020 11:10 pm

FrediFizzx wrote:
local wrote:
FrediFizzx wrote: Oh, you are right sort of. "His point is that the postulate that a measurement must result in an eigenvalue of the observable is not necessarily always true." It is that part that I am not sure I agree with. What does that mean with regards to the EPR experiment scenario? That a click is not recorded for every particle?

Margenau famously rejects projection in any form for any scenario, so he means that after one side does its measurement, the other side's source state is not physically projected (changed) in any way. Quantum mysterians and Bell acolytes must apply Luders projection to get a pure state superposition at the second side (because without that you cannot derive the cosine correlation). A less restrictive view is that there are some situations where it is OK to apply projection (though not necessarily Luders projection; it could be Von Neumann projection or something else) but EPRB is not one of them due to the separated measurements. No projection at all (null projection) is correct for separated EPRB.

Of course this rejection of quantum correlation applies for the usual spacetime. If spacetime is a 3/7-sphere then one can develop an argument that quantum correlation is in fact real. I am not qualified to assess the validity of such an argument.

If quantum correlation is rejected then Bell's Theorem cannot be proven, because the quantum and classical predictions coincide.

Ah yes, you are working to discredit the experiments. Hmm... Interesting as you may not be discrediting them in the way perhaps they should be discredited. Take this crazy plot for example,

Image

That plot actually exceeds CHSH by a lot. It gives 2.93 for CHSH. IOW, it is not even close to the quantum prediction but still exceeds CHSH. There are a lot of similar plots that do the same. So, perhaps the experiments are not really doing the quantum predictions. Just a thought.
.

The 2015 Vienna and NIST (Eberhard) experiments use a much less entangled state. Their statistics match quantum predictions well, for the state and measurements they were aimin at, but not for the EPR-Bohm singlet state and famous “optimal” measurements of the Tsirelson bound.

The 2015 Delft and Munich (CHSH) experiments aim at the singlet state and the Tsirelson optimal measurements, but only achieve a mixture of that state with a completely mixed random state. I forget the mixture proportions. Less than 50% noise (if there had been 50% noise, there could have been no violation of any Bell-type inequality. The state would have been a separable state.

So yes - the most interesting experiments are not “doing” the quantum state and measurements which you read about all the time in popular science and in undergraduate texts. Aspect, Weihs etc etc had massively inefficient detectors. Weihs at al only caught 1 in 400 of the photon pairs.

Experiments which do try to get the negative cosine by aiming for the singlet state and by looking at all pairs of measurement directions in one plane *all* have a massive problem of detector efficiency, ie they miss lots and lots of the “particles” and even many of the *particle pairs*, they don’t even know how many they missed! This can all be “fixed” only by making reasonable further physical assumptions, but depends, in other words, on partly assuming (aspects of QM) that which you wanted to prove.
gill1109
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Re: Margenau's argument

Postby local » Mon Oct 19, 2020 1:18 pm

gill1109 wrote: Their statistics match quantum predictions well...

Really?! Document your specific derivation of the quantum prediction for space-like separated systems. Don't try to be cute and use the joint prediction. You can't do it without Lorentz-invariance-violating Luders projection. Call this Graft's theorem (hope he doesn't mind). :ugeek:

This can all be “fixed” only by making reasonable further physical assumptions, but depends, in other words, on partly assuming (aspects of QM) that which you wanted to prove.

Gill admits that the experiments are nonsense because they rely on circular logic. The cognitive dissonance must be crippling for him.
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Re: Margenau's argument

Postby gill1109 » Mon Oct 19, 2020 8:51 pm

local wrote:
gill1109 wrote: Their statistics match quantum predictions well...

Really?! Document your specific derivation of the quantum prediction for space-like separated systems. Don't try to be cute and use the joint prediction. You can't do it without Lorentz-invariance-violating Luders projection. Call this Graft's theorem (hope he doesn't mind). :ugeek:

This can all be “fixed” only by making reasonable further physical assumptions, but depends, in other words, on partly assuming (aspects of QM) that which you wanted to prove.

Gill admits that the experiments are nonsense because they rely on circular logic. The cognitive dissonance must be crippling for him.

Statistics match predictions: I refer you to https://journals.aps.org/pra/abstract/10.1103/PhysRevA.99.022112

Cognitive dissonance: It’s not my problem. It was a problem for physicists, till at last they managed to avoid the detection loophole. That’s why the 2015 experiments were a big deal.
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