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Does superdeterminism save quantum mechanics?

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Re: Does superdeterminism save quantum mechanics?

#91

Post by myridium »

naasking wrote: post #81
myridium wrote: post #72

Earlier quoted context omitted.

I'll have to look into those derivations. Thanks. > There is an additional postulate, namely that the state vector is the real world we inhabit. Well, yes, it's a model for the physical world. Refusing to accept that the state vector is the real world we inhabit is tantamount to rejecting the existence of an objective universe, in which case any discussion is moot, or to the outright rejection of quantum theory, whic…

> Well, yes, it's a model for the physical world. Refusing to accept that the state vector is the real world we inhabit is tantamount to rejecting the existence of an objective universe, in which case any discussion is moot Some physicists consider the wave function to be ontologically inadequate to explain the physical world. See the discussion of "bohmian mechanics being many worlds in denial" for some details and…

It may be inadequate, but the consequences of quantum theory still apply without having to add new postulates. Among those consequences is many worlds.

Re: Does superdeterminism save quantum mechanics?

#92

Post by kgwgk »

myridium wrote: post #90
8note wrote: post #73

Earlier quoted context omitted.

There's is definitely an axiom built into many world's. Something along the lines of "things we don't observe are as valid and exist as much as things we do observe" That's an addition over the usual "things we observe exist"

Except we do observe interference effects. I'm not sure what you mean.

The interferences are part of those things that we observe and exist.

Re: Does superdeterminism save quantum mechanics?

#93

Post by bollu »

myridium wrote: post #38
naasking wrote: post #24

Earlier quoted context omitted.

I think that's more or less correct. GR suggests "time" isn't independent, we instead have 4-dimensional "spacetime". The idea that future inputs can influence past configurations can be perfectly sensible in this context. It's like a restricted form of consistent closed timelike curves. There was some development in this direction years ago: The Logic of Quantum Mechanics Derived from Classical General Relativity, h…

Why is GR required? Already in standard QFT (Minkowski metric; flat spacetime; special relativity) the propagator 'violates causality'. Although that phrasing is misleading; it doesn't mean there's any logical inconsistency. 'The future affects the past' you might say. Yes, well, all information about the future is derivable from information about the present. So actually those 'future influences' are determined by t…

I don't follow the comment about analyticity. I thought fields were real analytic, which meant one needed to use a power series to expand them, which has a potentially infinite amount of information in the Taylor coefficients? So I don't see how the local data "effectively" captures non local information.

Re: Does superdeterminism save quantum mechanics?

#94

Post by shellac »

raylad wrote: post #89
Koshkin wrote: post #82

Earlier quoted context omitted.

Even as an artifact of a lack of knowledge, probabilities can do many things - correlate, interfere...

I don't see how one's lack of knowledge can cause lines to form differently (different interference patterns). If anyone has any more insight into this, please do weigh in.

It's a good question. The interference pattern is a result of two things:

1) Quantum mechanics: the pilot wave or whatever you want to call it.

2) Incoming particles' positions having a broad statistical distribution.

With a cunningly skewed / rigged distribution you wouldn't see fringes (e.g. suppose they all come in on the same trajectory). However such distributions are atypical.*

But we talk about probability being a 'measure of ignorance' here because we don't know where these particles are exactly, but we know they must have gone through the initial slit, and QM says: in that case, here's the probability it will end up at this final destination.

* This the same story as statistical mechanics. (Having said that we do have the issue there that our systems start in low entropy, or 'atypical', states. That's a whole other topic)

Re: Does superdeterminism save quantum mechanics?

#95

Post by [deleted] »

8note wrote: post #68
raylad wrote: post #55

I got a bit lost at the double slit experiment with superdeterminism. Can someone clarify what is supposed to be going on? * We send one photon at a time through a double slit, don't measure them, and an interference pattern is formed, presumably because the probabilities of the particle going through each slit interfere with each other. * If we measure the position of the particle, it goes through only one slit, and…

Nit: the single slit case still gives you an interference pattern. It's just that it's a single slit pattern and not a double slit one

[deleted]

Re: Does superdeterminism save quantum mechanics?

#96

Post by lmm »

rafaelero wrote: post #75
raylad wrote: post #69

Earlier quoted context omitted.

It seems that can't be true, because if you randomly decide after the particle is launched whether to measure it or not, the interference pattern still appears. So it's not the measuring that does anything in superdeterminism apaprently, it's that if you do measure it, that was "known" in advance by the state of the universe. If not that, what is supposed to be going on (physicists please respond).

> if you randomly decide after the particle is launched whether to measure it or not, the interference pattern still appears. So, if you run an experiment and in 50% of the time the machine measures the particles and in 50% don't, does it still form an interference pattern in both cases? That does seem odd. I would expect that whenever a measurement is made, the interference pattern would disappear.

It forms a weaker interference pattern - imagine superimposing 50% of the interference pattern and 50% of the non-interfering look.

There's also the fun of the delayed-choice quantum eraser experiment, where if you measure (or not) which slit the photon went through after measuring the interference pattern (or not), you see (or don't see) the interference pattern.

Re: Does superdeterminism save quantum mechanics?

#97

Post by lmm »

naasking wrote: post #41
myridium wrote: post #29

Earlier quoted context omitted.

Totally agree. It's therapeutic to read this. Last I checked, many-worlds is a consequence of current quantum theory, not a postulate or additional axiom. Yet people treat it like such. Probably because it's 'spooky'. Then indeed it's ironic that they search for alternative explanations which try to say the same thing as many worlds but without saying 'many worlds'.

> Last I checked, many-worlds is a consequence of current quantum theory, not a postulate or additional axiom. There is an additional postulate, namely that the state vector is the real world we inhabit. This may seem obvious to you and not amount to postulating much or anything with any substance, but that's a philosophical claim that isn't suggested by the physics. There are also the problems of deriving the Born r…

> There is an additional postulate, namely that the state vector is the real world we inhabit. This may seem obvious to you and not amount to postulating much or anything with any substance, but that's a philosophical claim that isn't suggested by the physics.

Any interpretation has to postulate that something "is" the real world, in that sense. Postulating that there's an additional entity dependent on the wavefunction that "is" the real world (as e.g. pilot-wave theories do) is violating Occam's Razor.

> There are also the problems of deriving the Born rule from the existing postulates of MWI.

There are, but again, all interpretations have that problem, and adding more postulates just makes it worse. E.g. if you take a Copenhagen interpretation you have to derive the probability rule and a rule for what constitutes a "measurement" that triggers when the rule should be applied.

Re: Does superdeterminism save quantum mechanics?

#98

Post by temp438 »

graycat wrote: post #13
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…

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…

>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.

I don't get it. Alice knows it right away only if she knows the rules of the game, electricity in her brain doesn't need to move a light year away. Though, if she's braindamaged, it can take longer than a light year for her to figure that out or may never happen at all.

Re: Does superdeterminism save quantum mechanics?

#99

Post by temp438 »

thinkski wrote: post #88
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.

It’s also an inconvenient idea. For instance, how can one be guilty of a crime if one had no choice in committing it? Why try at anything if you have no choice — everything that will happen was decided at the universe’s origin and is merely playing out. It’s nihilism to the extreme. Then again, the quantum idea of true randomness isn’t much better — if human choice stems from a coin flip, can you really call it a con…

> For instance, how can one be guilty of a crime if one had no choice in committing it?

Guilty is a social concept derived from the assumption that some events in the universe are "bad"

> Why try at anything if you have no choice — everything that will happen was decided at the universe’s origin and is merely playing out.

> It’s nihilism to the extreme.

Realising that there is no free will is not smth negative or positive. It's just smth which sets your further path which had no other purpose but spreading Life in the universe

Re: Does superdeterminism save quantum mechanics?

#100

Post by naasking »

lmm wrote: post #97
naasking wrote: post #41

Earlier quoted context omitted.

> Last I checked, many-worlds is a consequence of current quantum theory, not a postulate or additional axiom. There is an additional postulate, namely that the state vector is the real world we inhabit. This may seem obvious to you and not amount to postulating much or anything with any substance, but that's a philosophical claim that isn't suggested by the physics. There are also the problems of deriving the Born r…

> There is an additional postulate, namely that the state vector is the real world we inhabit. This may seem obvious to you and not amount to postulating much or anything with any substance, but that's a philosophical claim that isn't suggested by the physics. Any interpretation has to postulate that something "is" the real world, in that sense. Postulating that there's an additional entity dependent on the wavefunct…

> Postulating that there's an additional entity dependent on the wavefunction that "is" the real world (as e.g. pilot-wave theories do) is violating Occam's Razor.

Not really, because in Bohmian mechanics the wave function is nomological, ie. not real, and merely describes a law of motion. Bohmian mechanics is kind of the dual of many worlds in this sense, and so requires no more postulates.

> There are, but again, all interpretations have that problem

Since you mentioned Bohmian mechanics, the Born rule was derived from the postulates a long time ago, and the Bohmian form of Schrodinger's equation is structured in a such a way that the quantum component goes to zero in the limit, thus reducing to classical mechanics.

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