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How Bell’s Theorem proved ‘spooky action at a distance’ is real

quantamagazine.org

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Re: How Bell’s Theorem proved ‘spooky action at a distance’ is real

#311

Post by GoblinSlayer »

kovac wrote: post #250

I'm not a Physicist. From what I understand, Bell's theorem only covers local hidden-variables and that this can still be explained using non-local theories like Bohm's. Can someone shed a bit of light on the non-local theories and if Bell's theorem addresses those as well?

Bell's theorem is a mathematical theorem and has narrow scope, it addresses local hidden variables theories and says they won't fly, it does nothing else, and doesn't prove spooky action at a distance either - that's author's addition.

Re: How Bell’s Theorem proved ‘spooky action at a distance’ is real

#312

Post by chopin »

fungiblecog wrote: post #262

It did not prove that. It proved that at least one of three assumptions about the universe is violated: Statistical Independence, Locality or Determinism. The usual assumption is that Locality has to go, but that is not necessarily true. It is possible that Statistical Independence is not true for the experimental systems that have been studied. See for example: https://www.frontiersin.org/articles/10.3389/fphy.2020.…

If you forgo statistical independence isn't that a kind of super-determinism?

Re: How Bell’s Theorem proved ‘spooky action at a distance’ is real

#313

Post by kolinko »

naasking wrote: post #125
kolinko wrote: post #24

Earlier quoted context omitted.

The analogy you mentioned is exactly the wrong one - it suggest that it’s just a matter of a hidden variable. A proper (but less elegant) would be: you have two balls with the same color or a pattern. You take one out. If you check the color first, you will find the other’s color the same, but the pattern sometimes different. If you check the pattern first, you will find the pattern the same, but the color sometimes…

> The analogy you mentioned is exactly the wrong one - it suggest that it’s just a matter of a hidden variable. It is equivalent to a hidden variable, just a non-local one.

his analogy suggests there is a local hidden variable.

Re: How Bell’s Theorem proved ‘spooky action at a distance’ is real

#314

Post by goldenkey »

chopin wrote: post #312
fungiblecog wrote: post #262

It did not prove that. It proved that at least one of three assumptions about the universe is violated: Statistical Independence, Locality or Determinism. The usual assumption is that Locality has to go, but that is not necessarily true. It is possible that Statistical Independence is not true for the experimental systems that have been studied. See for example: https://www.frontiersin.org/articles/10.3389/fphy.2020.…

If you forgo statistical independence isn't that a kind of super-determinism?

Even ordinary interpretations of QM don't explain the source of randomness in QM. This randomness can be entirely deterministic which would make the entire universe deterministic. So superdeterminism can still be the case, even if it isn't the reason for entanglement correlations. The entanglement correlations would instead be due to shared RNG references across spacetime, effectively nonlocal.

My point is, locality and superdeterminism aren't mutually exclusive, they are independent. All 4 combinations are logically possible with current experimental evidence.

https://www.americanscientist.org/article/quantum-randomness

Re: How Bell’s Theorem proved ‘spooky action at a distance’ is real

#315

Post by tsimionescu »

GoblinSlayer wrote: post #308
tsimionescu wrote: post #306

Earlier quoted context omitted.

> I'm not totally clear how the machines could work without actually taking a measurement, though. Here you're hitting on the heart of the Measurement Problem. In QM as it is understood today, unlike classical mechanics, there are two fundamentally different kinds of interactions between objects: quantum interactions and measurement. Quantum interactions are linear changes to the wave function, while measurements per…

They don't perceive each other when they evolve independently, i.e. when they are valid solutions of the schrodinger equation.

Valid solutions to the Schrodinger equation give you the wave function amplitudes in multiple places; the particles in these places can interact with each other still, even if they are 'the same particle'.

However, the wave function at different places interacts with the environment and start to shift in phase, eventually becoming unable to interfere with itself - this is called decoherence, and is a valid explanation about why and how we can't observe wave-like behaviors at large scales or in hot systems.

On the other hand, we can only postulate, based on observations, that when a particle interacts with a measurement device, the measurement device will show a single value with a probability determined by the amplitude of the particle's wave function at that point. We can postulate that the wave function collapses, or we can postulate that the device branches out into different devices in different worlds (enough such devices&worlds to achieve the probability distribution through observer selection somehow), or many other ways of formulating the Born rule. But whichever way you put it, this rule must be added to your system to predict experimental results, it does not derive from the Schrodinger equation.

Re: How Bell’s Theorem proved ‘spooky action at a distance’ is real

#316

Post by jostylr »

kovac wrote: post #250

I'm not a Physicist. From what I understand, Bell's theorem only covers local hidden-variables and that this can still be explained using non-local theories like Bohm's. Can someone shed a bit of light on the non-local theories and if Bell's theorem addresses those as well?

Bell was inspired by Bohm's theory. Having seen that a rational theory of existence was compatible with QM, Bell wanted to know if the nonlocality could be removed. Bell's work showed that it could not be removed. Bell was a proponent of Bohm's work. Bohmian mechanics is a perfectly sound theory, proven to be consistent and in agreement with quantum mechanics results whenever QM has results.

EPR (and more relevantly, Bohm's version of it involving spin entangled particles) showed that either one has hidden variables or nonlocality. Bell's work showed that local hidden variables is not possible. Hence, nonlocality is the conclusion and the argument to demonstrate the incompleteness of quantum mechanics falls apart.

The Many Worlds interpretations kind of gets away from this by exploiting another assumption in that work: that results from experiments actually happen in the sense that the other outcomes don't. Most people at the time would have just assumed that, but MW points out that experiments need not have definitive results, instead we have multiple results of experiments correlated with multiple versions of experimenters who think they have results. Thus, the correlations we see only need to be reconciled when the two groups of experimenters get together to compare notes, a perfectly local notion. Of course, some descriptions of MW, with branching of the universe, is rather nonlocal, but a proper formulation of MW is possible without any of that.

By the way, a key feature of Bohmian mechanics is the reliance on position as the "hidden variable". The spin of a particle is not an aspect of the particle itself, but rather of the wave function guiding the particle. In the spin experiments, the correlation with the environment once measurement has happened, separates the overlapping spin parts of the wave function and the particle is then being guided by that singular spin. Hence the appearance of the particle behaving as if it had that spin, but the particle is not actually spinning, whatever that would mean for a point particle.

Re: How Bell’s Theorem proved ‘spooky action at a distance’ is real

#317

Post by danbruc »

joe_the_user wrote: post #245
danbruc wrote: post #220

Earlier quoted context omitted.

I am not really sure what you are trying to say. Are you talking about the difference between an interpretation as a way of thinking about something and an interpretation as describing what something really is? It's like people who accept that general relativity specifies curved space, understand the implications but are still expecting to somehow find a higher dimensional space that all this is suspended in 'cause t…

"Interpretation", in the way that Copenhagen and Many-worlds are called interpretation, is just a way to add human meaning to an existing formalism. Like adding the label "energy" whatever quantity in Newtonian mechanics.

If many worlds is true, then there are actually countless parallel worlds, if pilot wave is true, then there is only one world. Those are metaphysical claims about the most fundamental aspects of the cosmos, I don't think it is fair to just file this under human meaning.

Re: How Bell’s Theorem proved ‘spooky action at a distance’ is real

#318

Post by mensetmanusman »

intrbelle wrote: post #280
morpheos137 wrote: post #87

Earlier quoted context omitted.

I don't know what you mean. The number of atoms involved in the free will delusion is infintesimal compared to the number of atoms in the universe. Number of atoms in 8 billion human brains: about 10^35 number of atoms in the universe about 10^82 according to search results. Maybe there are no aliens but homo sapiens are just the first stage of the universe becoming self aware.

You shouldn't even bother responding to the person that's claiming to be a research scientist in his/her profile and while he/she wrote such garbage at an attempt to justify such nonsense. HN is overcroweded with people that are against the notion of free will being an illusion. Even dang has a bias. All comments like yours just get unfairly downvoted until they're not visible.

There are so many fun consequences of no free will,

For one, if we don’t have free will, no one could bother one way or the other whether they argue about it.

It would also just be a feature of the universe that clouds of atoms take one position or the other :)

Re: How Bell’s Theorem proved ‘spooky action at a distance’ is real

#319

Post by unholiness »

newuser323 wrote: post #284
unholiness wrote: post #260

Earlier quoted context omitted.

Bell's theorem is strong: No local hidden variables can explain quantum entanglement. Your proposed fifth dimension is exactly such a variable – there is no set of values it can take on that explains the quantum phenomena we can easily and reliably observe. The fact that you think of it as a distance itself isn't important to Bell's theorem. Such a theory is cannot even obey relativity in our existing 3 dimensions (o…

Superdeterminism asserts what you're implying is incorrect.

Sure. There are assumptions you need for Bell's Theorem to apply. Statistical independence, single-outcome measurements, locality, determinism... All of these feel right to our scientific brains, but something's got to give.

So yes, you can throw out Bell's theorem if you're willing to throw out statistical independence with super-determinism. It's a tough leap to make, though. Super-determinism implies that there aren't really any laws of quantum mechanics. The fact that billions of quantum interactions have been observed in labs to obey consistent probabilities over time is pure coincidence. The fact that two entangled electrons always have opposite spin is pure coincidence. Nothing about the laws of the universe say you couldn't observe the other thing, it's just that the initial conditions of the universe prevented us from making measurements any time we would have measured otherwise. It's a tough pill to swallow.

My comment above is just saying you can't throw out Bell's theorem by saying "maybe there's a fifth dimension". I don't think GP meant a fifth dimension plus superdeterminism.

Re: How Bell’s Theorem proved ‘spooky action at a distance’ is real

#320

Post by unholiness »

goldenkey wrote: post #314
chopin wrote: post #312

Earlier quoted context omitted.

If you forgo statistical independence isn't that a kind of super-determinism?

Even ordinary interpretations of QM don't explain the source of randomness in QM. This randomness can be entirely deterministic which would make the entire universe deterministic. So superdeterminism can still be the case, even if it isn't the reason for entanglement correlations. The entanglement correlations would instead be due to shared RNG references across spacetime, effectively nonlocal. My point is, locality…

The fact that superdeterminism can violate statistical independence is what lets it violate bell's theorem, right?

If so GP's statement is just backwards: Super-determinism is a kind of forgoing statistical independence

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