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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

#321

Post by unholiness »

subroutine wrote: post #99
Gunax wrote: post #73

I've been posting this explaination for more than 10 years now: http://www.felderbooks.com/papers/bell.html I think I prefer Felder's explaination more than Quanta's. It's omitting some details (eg. the angles) but is better at explaining the difficulties of Bell's Inequality--why it seems like spooky action at a distance and why it cannot be used for communication.

One thing I've not been able to clarify is whether Bell accounts for the possibility that passing through a polarization filter could effect the waveparticle in some way, like altering its polarization angle.

Yes, the "altering" you're describing is what the theorem would call a hidden variable. Seems reasonable, but when you do the math it's exactly he kind of theory Bell's inequality rules out. There's no way to set the "polarization angle" (or any other set of variables) such that they obey the probabilistic laws we've observed (without violating some other assumption, like single measurement outcomes, statistical independence, determinism, or locality)

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

#322

Post by naasking »

breuleux wrote: post #278
naasking wrote: post #158

Earlier quoted context omitted.

> Of the 3 assertions in the abstract, the obviously false one is #2: "Any posthuman civilization is extremely unlikely to run a significant number of simulations of their evolutionary history". When you realize that running a simulation of the universe requires more processing power than is available in the universe, this is very obviously false. I think you've expressed a number of confusions. First, I think you co…

> Our brains are great at filling in information that we expect to be there, so even the parts that we directly perceive don't need to be simulated with complete fidelity. Right, but the simulation is nonetheless bottlenecked by whichever system requires the greatest fidelity, and the more technology advances, the more of a problem that becomes. For instance, medieval times would likely be far easier to simulate than…

> For instance, medieval times would likely be far easier to simulate than modern times,

Agreed.

> because the latter requires simulating our entire computer infrastructure.

Maybe, that isn't clear. There are probably plenty of optimisations here too if given some thought.

> I could use a solver on a big NP problem (we'll assume that P != NP), get a solution after an hour, and in theory, with some practice, I could probably check if the answer is correct in my head.

Yes, but note that we very rarely solve NP or EXPTIME problems exactly due to the costs. We often solve them heuristically or approximately, which wouldn't pose a problem for a simulation either.

Then there's also the possibility that we are simply not free to choose the problem to solve. When running a solver for an NP problem, we just need to input any kind of NP problem, and a simulation could easily have large sets of precomputed solutions available.

> Alternatively, the simulation could mess with our minds so we never notice anything out of place, but at that point I'm not sure I understand the point of it

Depends on whether any such changes affects the point of the simulation. If the simulation is to test world-scale economic models, then isolated tribes wouldn't have much influence on those outcomes.

Then again, maybe the point is simply entertainment. Maybe we're just The Sims for post-humans, in which case there's no point anyway.

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

#323

Post by lisper »

GoblinSlayer wrote: post #307
lisper wrote: post #212

Earlier quoted context omitted.

> I don't get why reflection isn't an observation/interaction there either. I know this comment is going to get lost in the noise, but that is a really excellent point, one of the best that has been raised here so far. This is a point that is often glossed over, but it is actually really important, and quite challenging to explain without getting deep into the weeds. The answer is that passing through a half-silvered…

The reflection does affect the state of a macroscopic system - mirror, as momentum of the reflected photon changed and needs to conserve.

That's right. That's why when this experiment is actually done, the mirror is typically rigidly mounted to an optical bench, which is sitting on the surface of a planet. If the mirror were freely floating in zero G, the outcome would be different. It is a worthwhile exercise to calculate how small the mass of the mirror would have to be before you would actually notice a difference in the results.

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

#324

Post by drpre »

gpsx wrote: post #38
willyg123 wrote: post #4

What is the prevailing theory to explain quantum entanglement? Must there be another dimension we cannot access or measure that is not subject to the laws of relativity? (I understand the laws of relativity break down at the quantum level but please ELI5)

I think people get confused when they think that each object has a wave function. This is not correct. The universe has one wave function. The wave function consists of a bunch of possible states along with the coefficient for each state. You can think of each state as being a distinct snapshot of what the universe might look like - including for example the position and spin of each particle. In the example of two e…

I think what I get hung up on with explanations like this is, what changes once the wave function has collapsed? Are there observable characteristics before wave function collapse that become different after the wave function collapses?

Maybe this question just reduces to “how can we tell the difference between two entangled particles having always been in some state (but we didn’t know it) vs. being simultaneously in both states until we make a measurement?”

Based on other comments in this post, it seems like the answer may be: Bell’s theorem proves that classical explanations have an upper bound on correlations between the particles, but quantum mechanics predicts a correlation the violates the classical upper bound. And we can experimentally test the correlations in practice.

This is all very hard to wrap my head around.

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

#325

Post by ericb »

UncleOxidant wrote: post #169
dntrkv wrote: post #156

Earlier quoted context omitted.

Well, in my case, I don't believe our universe is a simulation, but I'm open to discussing the idea for fun and it does seem like a possibility. Whereas, most people that believe in creationism, believe it 100% to be the case and if you don't believe the same you are going to hell. I grew up in an evangelical Christian community and you can't really compare the two groups. Evangelicals are ready to die for this belie…

This is mostly the YECs (Young Earth Creationist - "the earth is 6000 years old" camp). There are other flavors like ID (Intelligent Design) that tend to hold things a good bit looser - and there are many different flavors of ID as well. But yeah, the YEC folks are completely "it's our way or the hellway!" and the Evangelicals have pretty much doubled down on YEC - that wasn't always the case, there used to be a lot…

The term "deist" fits some of those items, although.

Interestingly, I think some of the distinction as to why this idea is more palatable is that it doesn't require "supernatural" or "magic" deities. The "creator" could be just like us. We already have evidence that creating virtual worlds is possible--we do it ourselves with games, so I think it takes a lot less faith, as we have a limited proof of principle already.

Also, most magical creationism is totally untestable. You can make some predictions about a simulation, though. If simulations are subject to constraints, which is likely, you should be able to ascertain, in the design of the universe, that items with the biggest O might be subject to performance optimizations. If you find lazy loading, caching, or other performance optimizations at the smallest scale (biggest O), which is what this might predict, you at least have some hints.

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

#326

Post by ericb »

GoblinSlayer wrote: post #295
naasking wrote: post #158

Earlier quoted context omitted.

> Of the 3 assertions in the abstract, the obviously false one is #2: "Any posthuman civilization is extremely unlikely to run a significant number of simulations of their evolutionary history". When you realize that running a simulation of the universe requires more processing power than is available in the universe, this is very obviously false. I think you've expressed a number of confusions. First, I think you co…

When the simulator shows a previously unseen object, it must first simulate all its history accounting for all effects to ensure that the shown state is legit and doesn't expose the conspiracy. This state should also account for all future investigations. The easiest way to achieve this is to run a precise simulation, so it doesn't save any resources.

Maybe, but if you can segment out the unobserved items, and back-calculate it lazily, you could save a lot of processing and memory.

The place to implement an optimization like this would be at the items with the biggest O in your world, which is usually the smallest building block--what you'd have the "most" of, which would drive the largest memory and processing demands.

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

#327

Post by ericb »

joe_the_user wrote: post #113
ericb wrote: post #3

If we were in a simulation, would the speed of light be the processing speed of the universe as each area re-renders, and spooky action at a distance be two variables pointed to the same memory location, populated with a lazy-loaded value, with copy-on-write semantics? edit: seems like it is lazy loaded, so revised my summary.

There are no propositions that "we are in simulation" would imply (unless someone fundamentally lacks imagination). Being "in a simulation" doesn't imply that we're in simulation created by later humans, it doesn't give any indication how fine-grain the approximations are, etc. etc. "We're in a simulation" fundamentally discard Occam's Razor in the fashion of the belief in God as controlling everything. And thus this…

> There are no propositions that "we are in simulation" would imply (unless someone fundamentally lacks imagination).

Not true! It implies we might find performance optimizations, especially at the lowest level. Lazy loading, caching, pointers to constants, that sort of thing. It also doesn't discard Occam's razor. We actually have examples of simulated worlds (physics engines in games), so we know they are possible, unlike the flying spaghetti monster.

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

#328

Post by naasking »

kolinko wrote: post #313
naasking wrote: post #125

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. It is equivalent to a hidden variable, just a non-local one.

his analogy suggests there is a local hidden variable.

That too could be a valid analogy if "randomly grab one in each hand" isn't actually random, but only appears random. This would be analogous to superdeterminism.

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

#329

Post by serverholic »

rottc0dd wrote: post #275
serverholic wrote: post #215

Earlier quoted context omitted.

Please tell me you aren’t always this autistic

I think what OP means is, spookiness comes out of the fact that one particle that can be separated by huge distance from another particle, and both particles being in superposition of states, observing one particle can affect the state of another. It is not about state, that you do not know, but state that is not yet there. When one particle's state decomposes from superposition of states to a single state, given the…

Yes but I think what you both are missing is that this example is meant for laypeople. Nobody has ever claimed that this is literally entanglement and I can say from first-hand experience that it's useful to bridge the gap to actually understanding entanglement.

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

#330

Post by goldenkey »

unholiness wrote: post #320
goldenkey wrote: post #314

Earlier quoted context omitted.

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

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

Yes, the idea is that the past of both the detectors, experimenters, and particle producer were once interacting, relatively recently in the scheme of the human race (let alone civilization, the big bang, etc.) These correlations would be responsible for the entanglement correlations, not a shared nonlocal RNG reference, but rather an inherited local piece of an old reference.

Nonetheless, superdeterminism doesn't have to be doing anything conspiratorial, but the possibility of doing so, lets it violate Bell/CHSH inequalities.

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