[Retric]

All analogies are flawed because the underlying reality is different. They can still be useful if they can communicate some more abstract idea.

An analogy I like for entanglement is to picture two atoms that will both decay at the same time. You could place them on other sides of the planet and until one is observed to decay nobody learns anything because the timing is unpredictable. After the observation people agree with that timing independent of distance but can’t communicate anything because the timing was random. Still, having two people both knowing some fact at the same time which can’t be observed by outsiders is a useful in it’s own way.

What I like about this is it’s clear what’s going on is different from what’s being described, it’s describing a property of something, and it separates information from communication. On the other hand it’s got plenty of it’s own problems.

[0majors]

The problem with that analogy is it gives an illusion of understanding while being completely misleading about what Bell’s inequality actually tells us about nature.

The whole point of Bell’s inequality is that quantum entanglement is fundamentally different than classical correlation between two objects which have some opposite properties the observer simply does not know about before observing one of them.

It’s not helpful to use an analogy which teaches the reader the exact opposite of the point you are trying to make.

Your example with decaying atoms suffers from the same misunderstanding. Quantum entanglement is not about lack of information about some specific states, if that was the case, why would anyone talk about loss of locality?

Understanding entanglement and Bell’s inequality requires a completely different ontology than your everyday experience with classical objects. I highly recommend the video I linked above for an approachable explanation. It is not as simple as these analogies but at least it gets to the actual point of this result which tells us something profound about how nature works.

[Retric]

No so fast, Bell’s inequality only invalidates local hidden variables. It’s your interpretation that’s suggesting some local variable like a ticking clock was determining when those atoms would decay, but that’s not part of the analogy.

The many worlds interpretation is analogous to global hidden variables, and while out of favor, perfectly consistent with modern physics. That said, the core issue is IMO only a one dimensional property was correlated which hides a lot of the oddities involved.

[normac2]

You describe that as an analogy, but I always took that to be what it actually is (or at least one very simple example). Are you saying that that is how we interpret our experience intuitively, but we need a more radical account under the various mainstream interpretations of quantum physics (Many Worlds, Copenhagen, etc.)?

[0majors]

That’s right. Not only it’s an analogy, it is also a bad one and completely misleading, at least according to physics of the last 50 years. Note how the article frets about the loss of locality.

[normac2]

Hmn. Is that at least what we experience if we try it as an experiment (even if the underlying physics is quite different than what it seems)?

[Retric]

The only thing we experience from preforming at an experiment is the data it provides. As such from the data from existing experiments is where all the spooky action at a distance is actually observed.

https://en.wikipedia.org/wiki/Bell_test though none of them are quite definitive on their own https://en.wikipedia.org/wiki/Loopholes_in_Bell_tests. I wouldn’t read much into the loopholes, but they do demonstrate just how difficult this stuff is.