Does superdeterminism save quantum mechanics? • Hacker News Board

Re: Does superdeterminism save quantum mechanics?

#101

Post by naasking » Mon, Dec 20, 2021, 1:50 PM UTC

meroes wrote: post #20

"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 A…

What you describe is "quantum contextuality". What Sabine is saying is that so-called superdeterminism/giving up statistical independence implies the contextuality that is needed to explain quantum mechanics using hidden variables, and it does so in a simple way if we accept future input dependence.

Re: Does superdeterminism save quantum mechanics?

#102

Post by naasking » Mon, Dec 20, 2021, 1:52 PM UTC

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…

> 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.

Actually that's not correct. In Bohmian mechanics the wave function is not actually real, it merely describes a law of motion. You're doing what many MWIers do, and applying the ontology of MWI to other ontologies and concluding they assume redundancies. That's just not how it works.

Re: Does superdeterminism save quantum mechanics?

#103

Post by temp438 » Mon, Dec 20, 2021, 1:53 PM UTC

lmm wrote: post #53

geertj wrote: post #35

Earlier quoted context omitted.

I think these consequences are only conspirational if time is an independent variable? What if everything, the entire universe’s past, present, and future ‘happened’ at the same time, as a self consistent solution of some kind of underlying equation or set of rules? Our brain, the seat of our perception of time, is part of the same universe that we’re trying to explain. Maybe time is an artifact of the self referenti…

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.

> It makes a mockery of the idea of trying to do science at all - the experiments you take are already determined

The laws of physics were there before people started studying physics. Didn't make it less interesting for those who were interested.

Everything we do is a mockery - life expectation is 75 if you are lucky and universe doesn't care about your achievements

>you can't learn anything about what causes have what effects because you can't ever change a causal variable.

[shrugs]If you don't have free will, then how can you change smth? What part of a computer "learns" during gradient descent?

Re: Does superdeterminism save quantum mechanics?

#104

Post by naasking » Mon, Dec 20, 2021, 2:25 PM UTC

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?

Why do you think you had no choice in committing it? Are you saying these people don't have any reasons they think justified committing a crime? That seems clearly false in general. Certainly if someone was literally forced to commit a crime, ie. they didn't want to do it, then they are not guilty, but why wouldn't they be guilty if they wanted to commit the crime and then did so?

This is a common confusion in thinking about moral responsibility under determinism.

"Choice" is a process whereby a set of options is reduced to one. This process is typically driven by an individual's reasons for acting, ie. there existed a hypothetical set of possible actions Y, but I did action X from Y because of reason Z. Z counterfactually describes why X was selected from Y, and when Z is an internally held value/justification for acting, this is a person's "will".

When a person is "free" to use their will to make choices, then they are acting of their own free will. If they are instead coerced into choosing W from Y instead of Z, where W is defined by somebody else's values, then they are no longer free to act on their will. This is Compatibilism, where free will and moral responsibility are compatible with determinism.

I also think it's important to distinguish "free will" as used in ethics and "free will" as used in science, where they speak of the experimenter's freedom. They are simply not the same thing, because one is compatible with determinism where the other may not be.

> 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.

What you're describing is fatalism, not nihilism or determinism. Given some tragedy is caused by a person, consider two scenarios:

1. they wanted that tragedy to happen

2. they fought tooth and nail to prevent it from happening

It's very clear to most people that the person in scenario #1 should be held responsible, where in #2 they should not. #2 is fatalism and absolves a person of moral responsibility, but this does not describe what happens under determinism. Under determinism, the people who make bad choices wanted to make those choices, and being held responsible is the moral feedback they need to correct their flawed decision process.

Re: Does superdeterminism save quantum mechanics?

#105

Post by naasking » Mon, Dec 20, 2021, 2:29 PM UTC

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.

It's pretty hilarious that you think Sabine Hossenfelder doesn't understand standard quantum mechanics.

Re: Does superdeterminism save quantum mechanics?

#106

Post by naasking » Mon, Dec 20, 2021, 2:42 PM UTC

coderenegade wrote: post #48

graycat wrote: post #13

Earlier quoted context omitted.

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…

You might be interested in some code that illustrates the problem of hidden variables and the EPR paradox: https://pastebin.com/J4ZUhG8e . The issue is that we can't replicate what QM predicts (and experiments validate) using hidden variables without additional steps or assumptions. For example, in that code, there are a few possible ways we could still produce the QM correlation function with local hidden variables:…

> 3. We could bias the initial sampling of our hidden variables. The problem is, this requires that we know the setting of the detector ahead of time.

The standard computational approach to this is to define the distribution as lazily evaluated based on some future state. That's exactly what Sabine is suggesting for a superdeterministic theory.

> It essentially means that all QM experiments have predetermined outcomes, and for whatever reason, those outcomes are the outcomes we observe.

More or less. This doesn't seem to bother anyone when spin 1/2 particles are all governed by the Dirac equation "for whatever reason", but somehow people really seem to think it matters in this case.

Re: Does superdeterminism save quantum mechanics?

#107

Post by astrange » Mon, Dec 20, 2021, 5:56 PM UTC

lmm wrote: post #49

astrange wrote: post #17

Earlier quoted context omitted.

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

I do, it's called "quantum mechanics". It's the most thoroughly verified theory in the history of physics, and in my subjective opinion the most mathematically beautiful one. It is the greatest pinnacle of human scientific achievement. But people think the idea that things might superimpose on each other like waves is weird, it's not what they see everyday objects that are 10,000,000,000x larger behaving, so it can't…

What’s going on with gravity though? Actually, did they decide if the holographic principle is true yet?

Re: Does superdeterminism save quantum mechanics?

#108

Post by raylad » Mon, Dec 20, 2021, 6:25 PM UTC

shellac wrote: post #94

raylad wrote: post #89

Earlier quoted context omitted.

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 bei…

Right, in classical QM.

But in superdeterminism unless I'm really misunderstanding, they are basically saying that there are no probabilities at all because everything is predictable given the initial conditions of the universe, if you knew the hidden variables.

Any "probabilities" are just what one observes to happen, but they aren't doing anything any more, they are just the result of incomplete knowledge. If you knew the hidden variables, you would be able to predict everything exactly and there would be no probabilities as such.

In that case, what is creating the interference pattern and why?

Re: Does superdeterminism save quantum mechanics?

#109

Post by meroes » Mon, Dec 20, 2021, 6:32 PM UTC

naasking wrote: post #101

meroes wrote: post #20

"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 A…

What you describe is "quantum contextuality". What Sabine is saying is that so-called superdeterminism/giving up statistical independence implies the contextuality that is needed to explain quantum mechanics using hidden variables, and it does so in a simple way if we accept future input dependence.

Bell nonlocality is not the exact same thing as contextuality from what I’ve been able to find.

Re: Does superdeterminism save quantum mechanics?

#110

Post by rafaelero » Mon, Dec 20, 2021, 7:01 PM UTC

lmm wrote: post #96

rafaelero wrote: post #75

Earlier quoted context omitted.

> 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.

Ok, that's definitely not what OP said. Of course the particle still can interfere with itself after the slit, it's just that when the measurement is made, the pattern of two waves interfering gets much weaker/non-existent. Also, the experiment you are alluding to does not say what you think it says. Perhaps you will be interested on another video from Sabine. https://www.youtube.com/watch?v=RQv5CVELG3U&ab_channel=Sabin...