The Classical Channel

12:27 AM

In your model itself, the superdeterminism enters in the form: "Typically the LHV theories in the literature consider a hidden variable λ, given in ‘absolute’ coordinates, ... Yet in contrast one can assume a local coordinate (angle λ′) of the hidden variable relative to each detector orientation without loss of generality." This same form of superdeterminism was also discussed and defended by Sabine Hossenfelder in one of her papers.

However, what I find interesting in your paper is that you mention ‘nonreductionistic’ and “. . . no explanation in terms of prior events based on a reductionistic perspective.” One of my conclusions with respect to the emergent superdeterminism in Arnold Neumaier's thermal interpretation was exactly this, namely that it is mostly harmless, but will destroy reductionism.

vzn

5:29 PM

@ThomasKlimpel not sure about "superdeterminism". havent studied it. who introduced it? dont think some basic models of LHVs deserve to be called "superdeterminism". am a bit leery of the term "determinism". there are many very complex classical systems that its tricky to call deterministic vs nondeterministic, eg fluid dynamics.

re questioning reductionism, some of the ideas of the paper were later realized with the "emergent QM" research program. believe it is largely the right track and will have major effects on future QM development, believe it already has. to me QTT is largely under the emergent QM umbrella.

to me there is an argument to be made that Bells thm itself is reductionistic. have some new ideas on this wrt bloch sphere. just googled this yesterday & turned up some cool refs. others are following the lead.

Thomas Klimpel

7:16 PM

Sabine Hossenfelder & Timothy Palmer - Rethinking Superdeterminism

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vzn

bought Hossenfelders book awhile back, read & liked it a lot, recommend it. :) agree with some of her intuitions. shes a iconoclast, a phd standup comedian at times. thought the chapter interview with Lisi was nearly hilarious. cited her blog on fluid dynamics post once, think its deep.

Thomas Klimpel

The important part for me here is "The close formal similarity of the Schrödinger and Liouville equations suggests that linearity and indeterminism are not fundamental features of quantum physics." Tim Palmer doesn't make it clear whether he or Sabine came up with this, but it is a very strong and convincing argument.

In particular, this argument makes it clear that a non-linear modification of the Schrödinger equation itself is not helpful. It is nice nevertheless that Arnold Neumaier made it work without the need for a non-linear collapse or world-splitting. But accepting superdeterminism also at least opens the prospect of finding an actual "low dimensional" model whose statistical behavior gets described by Schrödinger equation.

Thomas Klimpel

8:27 PM

@vzn "dont think some basic models of LHVs deserve to be called superdeterminism" well, it is the loophole used by the LHV that qualifies to be called "superdeterminism". Before Sabine and Tim, this was seen as something negative. But just like nonlocality before Bell was seen as negative, it now turned into a neutral property that can be studied and exploited.

The word may not be the best one, because a stochastic model can also be superdeterminstic, if it violates the independence assumption of the state from the measurement settings. And this independence assumption is closely related to reductionism.

vzn

ok, looking over wikipedia defn of superdeterminism, maybe it was introduced by bell himself. iirc saw sabines recent article on subj. let me dig it up again. she has an arxiv paper with palmer also etc... the idea as formulated on wikipedia does not appeal to me. conspicuously there is no math. how would superdeterminism affect the math? that is the key question. think its also a stretch bordering on false from my pov to say that superdeterminism is the only (major) loophole in the bell thm.

Superdeterminism

In quantum mechanics, superdeterminism is a loophole in Bell's theorem, that allows one to evade it by postulating that all systems being measured are causally correlated with the choices of which measurements to make on them. It is conceivable that someone could exploit this loophole to construct a local hidden variable theory that reproduces the predictions of quantum mechanics. Superdeterminists do not recognize the existence of genuine chances or possibilities anywhere in the cosmos. Bell's theorem assumes that the measurements performed at each detector can be chosen independently of each...

the article also says its untestable/ unfalsifiable + "Citation needed."

Thomas Klimpel

@vzn The question is also how much superdeterminism is "needed", and where it comes from. The assumption of independence can be more or less violated.

I think I read somewhere that giving up 13% of "free will" (I guess this mean how much the independence assumtion is violated) is sufficient for allowing superdeterministic theories to reproduce the results of QM in Bell tests.

vzn

8:44 PM

@ThomasKlimpel what the original proof, and people seem to be missing is some kind of interplay between detectors and the hidden variables. it may seem to disrupt "independence" in some ways. but there is "independence" in statistics and "independence" in free will/ experimenter choices. people are getting tripped up on words that are not precisely mathematically defined. in this way the philosophers are inadvertently muddying the issue while attempting to clarify it.

Thomas Klimpel

And for Neumaier's thermal interpretation, I also think that there is a convincing explanation why the independence assumption is violated for sufficiently macroscopic systems.

vzn

need to look over neumaier work more. he knows a lot about QTT. think he has the rough outlines correct. but honestly feel that a "correct" theory of QM is going to lead to a LHV theory for EPR correlations. think it is close at hand. would like neumaier to tie in thermal interpretation more to objective/ CSL collapse theories, havent seen him do that.

Thomas Klimpel

I agree, speaking of "free will" is not really helpful. Sabine and Tim don't use that "free will" terminology. They explain why it was "a mistake" to dismiss superdeterminsim (i.e. abscence of complete independence between measurement settings and system state) as totally unacceptable. I see this on a similar level as that we learned to accept "nonlocality".

neumaier's thermal interpretation is an objective determinstic non-observable variable theory. However, it does not have a collapse, and that is a very important feature. The argument by Tim and Sabine explains why this is important.

The non-observable variables are the expectation values and correlations whose dependence of the spatial and temporal parameters is "too fast" to be measurable. So there is not a hard cutoff, but the non-observable variables go till infinity fast, and he also mentioned why this is somehow important.

vanlocal

9:11 PM

anyone have the Albert software?

Mithrandir24601

9:42 PM

@ThomasKlimpel hmph. I'm doing a PhD heavily involving nonlinear quantum optics. I am very fed up of being told quantum physics is linear

vzn

10:00 PM

@ThomasKlimpel ok thx for reminding me of this. think this is a very well written essay. its a top-down approach to solving or attacking the problem but believe her intuition is very accurate. my only qualm is calling it "superdeterminism" which sounds too exotic. suspect (or merely observe) that there are classical systems not too exotic that exhibit it.

in theory salon, Mar 16 '20 at 15:37, by vzn

How to Make Sense of Quantum Physics / hossenfelder/ palmer, quanta

if one was forced to pick a word, think maybe "intersection" or "interplay" or "emergence" might fit better.

yes, re "nonlocality" unfortunately its a term that has stuck. my preference would be something like "bell locality" that is taken to reference specific mathematical (statistical) properties relating to statistical dependence/ independence which cannot be assumed to be the same as experimenter independence/ choice.

Thomas Klimpel

@Mithrandir24601 Well, nonlinear quantum optics lives on a "low dimensional" model (at least the nonlinear parts), i.e. one where the phase space doesn't explode exponentially with every additional bit. In 3D, this is often still quite huge, because it will often scale with ^3 or even ^6. But because this is still a polynomial growth, it makes sense to call this "low dimensional".

Mithrandir24601

10:49 PM

That's a bit of a semantic argument. If it's nonlinear, it's not linear, regardless of how you define a bit... the equations are literally just not writable in a linear way

Thomas Klimpel

11:00 PM

The equation for the state you are directly interested in are nonlinear. But you could instead use equations for the state of your knowledge about that state. Those equations would be linear, but the phase space would be exponentially bigger.

Mithrandir24601

11:44 PM

@ThomasKlimpel considering how insanely useful this would be for high strength fields in SPDC and FWM, I would really like a reference for this

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The Classical Channel