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Does superdeterminism save quantum mechanics?

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Re: Does superdeterminism save quantum mechanics?

#71

Post by Koshkin »

myridium wrote: post #30
effie wrote: post #22

Earlier quoted context omitted.

Their goal is to find the deeper explanation behind wave functions, so obviously going back to wave function, even that of the Universe, is not very appealing to them.

Well if they insist on expressing the dynamics of the universe as the minimisation of a global (or local) action functional, then they are already throwing in the towel because that implies a wavefunction of the universe. I'm suspicious that these fringe quantum-physics-deniers just don't understand the mathematics. They want to be relevant but they don't want to learn, so they post wordy, fluffy blog posts targeted…

Except she does not "deny" quantum mechanics, and she does understand the math.

Re: Does superdeterminism save quantum mechanics?

#72

Post by myridium »

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…

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, which seems irrational. (i.e. "I don't believe the state vector represents our world, despite it being the best physical model of our time")

Re: Does superdeterminism save quantum mechanics?

#73

Post by 8note »

myridium wrote: post #29
quantum_mcts wrote: post #18

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…

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'.

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"

Re: Does superdeterminism save quantum mechanics?

#74

Post by lmm »

geertj wrote: post #56
lmm wrote: post #53

Earlier quoted context omitted.

It's still conspiratorial. You just happened to choose the right particles to measure? It makes a mockery of the idea of trying to do science at all - the experiments you take are already determined, you can't learn anything about what causes have what effects because you can't ever change a causal variable.

Well, I don’t know of any physical law that allows you to choose anything. Whether or not you believe QM is normally deterministic or super deterministic, you have to believe in something outside physics to make all of us not a necessary outcome of an initial state. That doesn’t diminish the pleasures or the reality of consciousness though, or the (illusion) of free will, at least not for me.

I'm not particularly concerned about free will. But we have to have some notion of effects following from causes if we're to be able to reason about physics at all - otherwise the universe might as well be just a pile of stuff happening one after another with no rhyme or reason to it. Superdeterminism undermines that completely.

Re: Does superdeterminism save quantum mechanics?

#75

Post by rafaelero »

raylad wrote: post #69
rafaelero wrote: post #66

Earlier quoted context omitted.

> Superdeterminism says that the initial state of the universe determined that we would measure the particle, and therefore it goes through one slit and there's no interference. Where did you get this from? I don't think Sabine implied that. From what I understood, it is more like the measurement interacted with the particle and it changed its behavior. I don't see why we need to consider that it was always meant to…

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.

Re: Does superdeterminism save quantum mechanics?

#76

Post by alex_young »

Koshkin wrote: post #63
alex_young wrote: post #60

> Once you understand what’s going on with the double slit, all the other quantum effects that are allegedly mysterious or strange also make sense. Take for example a delayed choice experiment. In such an experiment, it’s only after the particle started its path that you decide whether to measure which slit it went through. And that gives the same result as the usual double slit experiment. Delayed choice seems prett…

But reference frames do have physical significance (and the distance traveled does depend on one).

So, from the photon’s perspective (I know perspective isn’t right, but I’m not sure what else to call it), the distance traveled is 0, and the emitting and measuring happen instantaneously right?

What I’m struggling with is what it means to the experiment to move a measurement into the system between these events if they are at the same moment according to the thing being measured.

Re: Does superdeterminism save quantum mechanics?

#77

Post by bryan0 »

myridium wrote: post #64
bryan0 wrote: post #50

Earlier quoted context omitted.

The born rule for starters.

In QM, evolution is unitary. The Born Rule is an empirical observation that is adequately explained by the decoherence of a quantum system into entangled states of observer, environment, measurement apparatus and the system being measured. E.g. the master equation for a quantum density matrix governs its evolution when the environmental conditions are not completely known or modelled. Classical ensembles or 'decohere…

there might be some non-trivial deterministic unitary description via decoherence, but it should not be surprising that many people think that QM is non-deterministic.

Re: Does superdeterminism save quantum mechanics?

#78

Post by Koshkin »

raylad wrote: post #67
Koshkin wrote: post #62

Earlier quoted context omitted.

Well, the thing is, neither the standard (non-local) quantum mechanics nor the superdeterminism answer this question, as they both simply talk about a wave function and its taking a different shape depending on what measurement is made; the only difference is that one completely gives up on futher clarification of what the wave function physically represents while the other encourages looking for hidden variables.

I've heard the interference discussed as an "interference of probability amplitudes". But in superdeterminism, it seems as if there are no probabilities in that sense, or am I missing something?

Superdeterminism does not deny probabilities (just like, say, classical mechanics does not deny statistical mechanics).

Re: Does superdeterminism save quantum mechanics?

#79

Post by raylad »

Koshkin wrote: post #78
raylad wrote: post #67

Earlier quoted context omitted.

I've heard the interference discussed as an "interference of probability amplitudes". But in superdeterminism, it seems as if there are no probabilities in that sense, or am I missing something?

Superdeterminism does not deny probabilities (just like, say, classical mechanics does not deny statistical mechanics).

Not following.

If everything is predetermined, there are no actual probabilities except as an artifact lack of knowledge of what the outcome must be.

If that is the case, how can the probability amplitudes interfere with each other?

Re: Does superdeterminism save quantum mechanics?

#80

Post by Koshkin »

alex_young wrote: post #76
Koshkin wrote: post #63

Earlier quoted context omitted.

But reference frames do have physical significance (and the distance traveled does depend on one).

So, from the photon’s perspective (I know perspective isn’t right, but I’m not sure what else to call it), the distance traveled is 0, and the emitting and measuring happen instantaneously right? What I’m struggling with is what it means to the experiment to move a measurement into the system between these events if they are at the same moment according to the thing being measured.

A frame of reference that moves at the speed of light is non-physical. For example, using it you could conclude that objects that have non-zero mass, too, all move at the speed of light...
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