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Monday, October 31, 2022

What was that Bell Nobel Prize For?

The Bell fans lobbied for a Nobel Prize for 30 years, and they finally got it, so are they happy?

No. See this video, Tim Maudlin Corrects the 2022 Nobel Physics Committee About Bell's Inequality. He says the Nobel citation missed the point.

I don't want to pick a fight with Maudlin, as he is a very smart guy who explains this stuff very well. He has sharp disagreements with others about Bell's theorem, and I describe them here.

Another recent Maudlin video says:

[47:00] The theorem of Bell [and confirming experiments] is the most astonishing thing in the history of Physics.
Among other things, he gives a very good explanation of what is wrong with superdeterminism, as a Bell loophole. Here is a shorter interview.

Here is my view. When quantum mechanics (QM) was discovered in 1926, a lot of smart people wondered whether was a new type of theory, or if the uncertainties were just disguising an underlying classical theory. John von Neumann was the world's smartest man, and he convinced himself in 1932 that QM was different from any classical theory. Einstein co-wrote a 1935 paper speculating that QM might be completed by adding elements of physical reality. Bell showed in 1964 that the difference between QM and a classical theory could be quantified, and that was later confirmed experimentally by Clauser and the other Noble prize winners.

So the Bell work is no big deal, as it only confirmed what everyone thought.

Maudlin and the other Bell fans have another view. To be fair to Maudlin, I suggest his paper, What Bell Did, and his exchange with Werner, here and here.

He correctly says that Bell assumed locality, hidden variables, and statistical independence. Statistic independence is assumed by all of science, and is reasonable. Hidden variables are just the Einstein elements of physical reality, and he and Bell argue that any reasonable theory would have them. That leaves locality. The experiments showed that the Bell inequalities are violated, so that means that nature must be nonlocal.

He is right that if you accept hidden variable theory then you have to accept nonlocality. I just do not accept hidden variables.

He is also right that the Nobel citation failed to endorse the nonlocality conclusion.

There are also the superdeterminism and many-worlds loopholes, but Maudlin and the Nobel committee are right to ignore these. That leaves you with a choice -- you can have locality or hidden variables, but you cannot have both.

Maudlin would say that I and the Nobel committee suffer from a misconception that has gone on for decades.

It would take some very compelling evidence to convince me of nonlocality. As Maudlin says, if you snap your fingers, do you believe that what happens in your hand can depend on what happens in a distant galaxy? I say of course not, but Maudlin accepts that.

Wouldn't we see some examples of action-at-a-distance?

He gives an example pointing to nonlocality in the Aharonov–Bohm effect. I do not agree, but it requires technical explanation, and maybe I will post separately on it.

Maudlin says:

The reality of nonlocality has been settled. [3rd video, 18:45]
So what is nonlocal? There is no way to change one particle, and have that affect an observable of a distant particle. So the only things that are nonlocal are the mythical hidden variables.

Wikipedia describes Bell's theorem:

Bell's theorem is a term encompassing a number of closely related results in physics, all of which determine that quantum mechanics is incompatible with local hidden-variable theories given some basic assumptions about the nature of measurement.
Maudlin wants to remove the term "hidden-variable" from the picture, and deny that Bell made such an assumption. You can read Bell's 1964 original paper, and see for yourself that he assumes hidden variables. In later papers he called them "beables" and tried to argue that they could be assumed from first principles. But they have to be assumed somehow.

Discussions of Bell's Theorem sometimes get sidetracked by issues of probability and determinism. Some say Bell proved the world is indeterministic. Some say Einstein EPR objected to indeterminism. This is a red herring. There is some truth to it, but it has to be stated carefully, or it is misleading. Maybe I will make another post on this issue. I would say that Bell proved the impossibility of local hidden variable theories, whether they are deterministic or stochastic. Ultimately all theories are stochastic anyway, as all measurements and predictions have errors.

3 comments:

  1. Dear Roger,

    1. Re: First video ["Tim Maudlin corrects..."]
    32:50 -- 33:10: LOL! Well, how about RQM? Like, you know, Dirac's, if not QFT?

    Throughout, Maudlin seems to suggest that the full integration of GR + QM would be required to conclusively argue in favour of locality. Nope. SR + QM should be enough, and RQM already has it. It's just that Maudlin doesn't refer to it.

    He also seems to take the wavefunction of the *mainstream* QM (or QED or QFT) to be "real" (i.e. ontic). Wrong. In the mainstream QM, \Psi lives in higher-dimensional configuration spaces, and even Norsen has had hard time putting it in correspondence with the 3D space (the last time I checked out his research). Also, the mainstream QM has Measurement Problem unresolved. How can \Psi lead to random and irreversible measurement events, if it's real?

    2. The shorter interview (the third) is the best, but still not all of the positions that Maudlin takes are consistent.

    3. No hidden or extra variables are required to make full sense of the phenomenology (the accumulated body of experimental observations and context) pertaining to quantum phenomena. I published a paper on it (the ICCTPP iqWaves paper), albeit only with NRQM. Work is in progress for the SR-extension of iqWaves (and progressing fine).

    Aside: Bohmians (and all other hidden variables folks) are clearly on a wrong track.

    4. Aside: The idea of non-locality can be easily regarded as having been settled if you refer exclusively to the NRQM. But the real world isn't non-relativistic. Yet, all discussions of Bell's inequalities refer to NRQM, which builds a kind of a false field of perceptions that is attuned to receiving claims of nonlocality. [In evidence, see point 1. above.]

    That is so, even if Maudlin argues that whether the specific theory of QM is valid or not, it doesn't matter. The fact that the Bell inequalities are violated itself means that locality is violated. Strictly speaking, this is a hasty generalization, but I won't argue about it for now. I would return to this issue, may be, a year later when the SR-extension of my iqWaves theory is complete. Development of theory is important; discussions and debates aren't.

    5. Unless people clearly identify the ontological bases of all theories being compared and contrasted, they would be shooting in the dark. Tricks are far more likely in such a scenario; Truth isn't. History since at least 1926 (if not 1912 or 1905 or 1900 or 1865) is witness.

    Best,
    --Ajit

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  2. "The fact that the Bell inequalities are violated itself means that locality is violated." No, not true, whether in relativistic or non-relativistic QM. It only means that local hidden variable theory is wrong.

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    Replies
    1. Yes, my mistake. I had in the mind, and should have said:

      "That is so, even if Maudlin argues that whether the specific theory of QM is valid or not, it doesn't matter. The fact that the Bell inequalities are violated itself, according to him, means that locality is violated."

      Something like this "according to him" bit slipped out while writing. Thanks for catching it!

      Best,
      --Ajit

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