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Does superdeterminism save quantum mechanics?

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Re: Does superdeterminism save quantum mechanics?

#11

Post by midjji »

astrange wrote: post #7
d--b wrote: post #5

I can’t agree more with the OP about free will and stuff. The main problem of superdeternimism though is that it both explains everything and nothing. It’s like giving up.

The explanation of superdeterminism she gives here isn’t a “full” superdeterministic theory (nothing actually happens over time, there are no physics, the universe is just a movie being played back, etc) and she does say it only applies at the quantum level. So there’s still room for science.

Just means she hasn't thought of the inevitable consequences. Besides, the paradox she is resolving isn't a paradox, she just does not understand the answer in standard QM.

Re: Does superdeterminism save quantum mechanics?

#12

Post by kgwgk »

graycat wrote: post #6

Uh, the OP frequently mentions "statistical independence", and I am uncomfortable with that: Independence is a property of a set of more than one random variable and is defined in probability , often used in statistics , but not defined in statistics . There is a polished, elegant, and thorough treatment of such independence, including of uncountably infinite sets of random variables, in J. Neveu, Mathematical Founda…

I guess the whole field of statistical mechanics would make you uncomfortable.

Re: Does superdeterminism save quantum mechanics?

#13

Post by graycat »

PeterWhittaker wrote: post #8
graycat wrote: post #6

Uh, the OP frequently mentions "statistical independence", and I am uncomfortable with that: Independence is a property of a set of more than one random variable and is defined in probability , often used in statistics , but not defined in statistics . There is a polished, elegant, and thorough treatment of such independence, including of uncountably infinite sets of random variables, in J. Neveu, Mathematical Founda…

In the context of Bell’s Theorem, statistical independence is understood to mean that, if extant, hidden variables are not correlated with how measurements are being performed. Bell’s Theorem is only correct if this assumption holds. Hossenfelder is arguing that the assumption is incorrect: that Bell’s Theorem is incorrect precisely because there ARE hidden variables and that these ARE correlated with measurement set…

At least for now, I'm willing to f'get about issues of "free will".

Thanks, I will keep trying to make sense out of Bell's work.

I keep getting stuck trying to read quantum mechanics: One place was the claim that the wave functions form a Hilbert space. Nope: As I read in W. Rudin, Real and Complex Analysis, a Hilbert space is a complete inner product space where complete means that every Cauchy convergent sequence is convergent. Well, while the wave functions are likely points in a suitable Hilbert space, they can't be complete, e.g., they can converge to a point in the space, i.e., a function, that is not continuous and, thus, not differentiable in contradiction to the assumption that all wave functions are differentiable. I admit that this is a small point, but I was trying to take quantum mechanics seriously and be careful.

Closer to the OP, another place I got stuck was in the approaches of physics to independent and uncorrelated: In probability theory those two are not the same: For two real valued random variables, independence implies uncorrelated. As in W. Feller, in the case of two real valued random variables with joint Gaussian probability density function, uncorrelated implies independence. Generally, however, uncorrelated does not imply independence. Independence is a much stronger property than uncorrelated. Maybe eventually I will figure out what physics means by "uncorrelated", especially for Bell's work.

To me, we can take the Ace of Hearts and the Ace of Spades, shuffle them, and deal them out, face down, one each to Bob and Sally. Bob can go a light year away. Sally then looks at her card and knows right away, nothing faster than the speed of light needed, what Bob's card is.

We know all the associated probability distributions for Bob and Sally. And we know that as soon as the cards are dealt what each of Bob and Sally have is determined -- so far unknown but still determined.

I'm guessing that this Bob-Sally thought experiment may have something to do with entanglement, the EPR (Einstein, Podolsky, Rosen) paradox, "spooky action at a distance", collapse of quantum mechanics wave functions, and Bell's results -- but I need to keep studying.

Re: Does superdeterminism save quantum mechanics?

#14

Post by candiodari »

6gvONxR4sf7o wrote: post #10

Superdeterminism needs some kind of simplicity, for lack of a better word. To take her vaccine trial analogy further, imagine that you randomly assign a group of 100 people to a treatment and control cell (50-50). It could happen that all 50 people in the control cell just happened to be the 50 most a priori healthy people in the group. But it’s extremely unlikely. Following the analogy, superdeterminism says it happ…

The point is that it's only unlikely (or other situations likely) if the events, even from patient to patient, are random. If whether a patient is sick or not determined if they're in the placebo group or the healthy group, you would be testing exactly nothing. The randomness in placing the patient is a required part of the experiment. And more than random, the patient placement must be random and independent from their disease status (misdiagnosed healthy patients get treated too, after all. Generally it works quite well, as there isn't any problem to solve) and whether the treatment will work.

And of course superdeterministic theories are "simple". In the same sense that you can model any sequence as a function: just list all observed values for all time. Very simple, very little predictive power when you need it.

That also gives you the criticism of superdeterminism: if we do things that way, nothing needs an explanation, as it just can't be simplified from that full specification that we observe ... so there's no point to science. Note that it can still be more complex than we'll ever usefully realise, so whilst it means everything is determined, it does not necessarily (in fact quite unlikely imho) make it predictable for us limited beings.

But, in at least one meaning of the word, it's certainly simple. Every function in physics, whether quantum gravity or electroweak forces or the number of puppies your cat will have next year: f(x) = the x'th entry in the table ... (tables, of course, that you generally don't have access to)

Which isn't to say this is a strategy that can't work and perform useful functions. Take a robot for example, and look at inverse kinematics. That comes with 3d calculus, volume intersection (robot mustn't self-intersect), and there's not just limits in position but in speed, acceleration and torque as well. You can fully develop this theory. Or you can move the robot, observe all variables and save them to disk, then use nearest neighbour to figure out robot movement. Works like a charm, and doesn't even need to know how many arms the robot has. And while it takes a while, I bet it's a hell of a lot faster than building the theory for even the simplest of robots, never mind multi-armed or nonlinear robots. Plus it's trivial to make a machine learning algorithm do it for you, and the same can't be said of developing the correct theory for a new robot model.

Re: Does superdeterminism save quantum mechanics?

#15

Post by akvadrako »

PeterWhittaker wrote: post #8
graycat wrote: post #6

Uh, the OP frequently mentions "statistical independence", and I am uncomfortable with that: Independence is a property of a set of more than one random variable and is defined in probability , often used in statistics , but not defined in statistics . There is a polished, elegant, and thorough treatment of such independence, including of uncountably infinite sets of random variables, in J. Neveu, Mathematical Founda…

In the context of Bell’s Theorem, statistical independence is understood to mean that, if extant, hidden variables are not correlated with how measurements are being performed. Bell’s Theorem is only correct if this assumption holds. Hossenfelder is arguing that the assumption is incorrect: that Bell’s Theorem is incorrect precisely because there ARE hidden variables and that these ARE correlated with measurement set…

> Superdeterminism, arguably misnamed, simply argues that QM is deterministic, where Bell and others have argued it is not.

No, this is completely wrong. Super-determinism is more than determinism. Super-determinism is about conspiratorial coincidences – so the measurement settings you choose just happen to be the ones which will make it look like the world is quantum.

Other quantum interpretations are also deterministic, like many worlds and pilot wave theory. Bell's theorem doesn't assume determinism, but most importantly (1) locality (2) counterfactual definiteness (3) a single classical world (4) no retro-causality and (5) no super-determinism.

Re: Does superdeterminism save quantum mechanics?

#16

Post by [deleted] »

akvadrako wrote: post #15
PeterWhittaker wrote: post #8

Earlier quoted context omitted.

In the context of Bell’s Theorem, statistical independence is understood to mean that, if extant, hidden variables are not correlated with how measurements are being performed. Bell’s Theorem is only correct if this assumption holds. Hossenfelder is arguing that the assumption is incorrect: that Bell’s Theorem is incorrect precisely because there ARE hidden variables and that these ARE correlated with measurement set…

> Superdeterminism, arguably misnamed, simply argues that QM is deterministic, where Bell and others have argued it is not. No, this is completely wrong. Super-determinism is more than determinism. Super-determinism is about conspiratorial coincidences – so the measurement settings you choose just happen to be the ones which will make it look like the world is quantum. Other quantum interpretations are also determini…

[deleted]

Re: Does superdeterminism save quantum mechanics?

#17

Post by astrange »

midjji wrote: post #11
astrange wrote: post #7

Earlier quoted context omitted.

The explanation of superdeterminism she gives here isn’t a “full” superdeterministic theory (nothing actually happens over time, there are no physics, the universe is just a movie being played back, etc) and she does say it only applies at the quantum level. So there’s still room for science.

Just means she hasn't thought of the inevitable consequences. Besides, the paradox she is resolving isn't a paradox, she just does not understand the answer in standard QM.

Seems like if you “thought of the consequences” and “understood QM” here you’d have a theory of everything all ready to go.

Re: Does superdeterminism save quantum mechanics?

#18

Post by quantum_mcts »

I'm from the many-worlds interpretation camp, and this "superdeterminism" business always strikes me as ironic.

Proponents of hidden variables, in their desire to explain QM effects, arrived at the idea that there is something that permeates the Universe since the Big Bang and participates in every physical interaction. Existence of this something cannot be directly proven - since we are "inside" of it.

How about the "wave function of the Universe"?

Re: Does superdeterminism save quantum mechanics?

#19

Post by nimish »

There are other possible choices that reject superdeterminism but are still ok: https://arxiv.org/abs/1907.05607 -- you have to abandon either locality or the assumption that observed events exist absolutely

Personally I think it's easiest to reject the "absoluteness" of events and subscribe to RQM or QBism. Superdeterminism is a little boring if ultimately plausible.

Re: Does superdeterminism save quantum mechanics?

#20

Post by meroes »

"If statistical independence is violated, this means that what a quantum particle does depends on what you measure."

But in standard QM without superdeterminism, what a particle does already depends what you (i.e. the experimenters) measure - how you set the relative angles of your detectors determines the amount of correlation, even when setting them at spacelike distances after the entangled pair is released (say Alice chooses hers and Bob his without any communication between them.

It's the same physical facts and we either take superdeterminism or quantum nonlocality (or other interpretations not at issue here). To me the conspiracy of superdeterminism is too great.

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