Spooky action at a distance and various interpretations of QT

[gentzen]

I'm not sure what to think about her video.

Her video is disappointing in various ways. For example, she cheery picks quotes from Nicolas Gisin, Anton Zeilinger, and Tim Maudlin, (and also from a paper by Shimony, Horne, and Clauser) only to conclude:

As you can see, we have no shortage of men who have strong opinions about things they know very little about, but not like this is news.

She ends her video saying:

Call me crazy if you want but to me it’s obvious that superdeterminism is the correct explanation for our observations. I just hope I’ll live long enough to see that all those men who said otherwise will be really embarrassed.

Before the end she repeats an important point she already made in 2011:

But if you want to find out whether measurement outcomes are actually determined, you have to get out of the chaotic regime. This means looking at small systems at low temperatures and measurements in a short sequence, ideally on the same particle. ... And this makes me think that at some point it’ll just become obvious that measurement outcomes are actually much more predictable than quantum mechanics says. Indeed, maybe someone already has the data, they just haven’t analyzed it the right way.

She also hints at an important point about how violation of "statistical independence" actually plays out:

Well, that’s entirely unsurprising. If you considered measuring something but eventually didn’t, that’s just irrelevant. The only relevant thing is what you actually measure. The path of the particle has to be consistent with that.

But I find this too little, and not well explained. From my perspective, this would have been the place to explain the impression that the initial state is "fine tune", and why this is not a problem.

Another huge disappointment for me was that some of the arguments got dropped completely, arguments where I was never sure whether it was Tim Palmer who contributed them. For example, I noticed before that Palmer put more stress on the importance of the similarity between von Neumann equation and Liouville equation and the relation to the linearity of QM. There was a seminar where both mentioned it (Hossenfelder at 13:24 and Palmer at 46:21), and Palmer excusing himself for repeating Sabine, "but I want to again stress..." hinted that for him, this was not just something "obvious", but something deep and imporant.

 

[Jarvis323]

But I find this too little, and not well explained. From my perspective, this would have been the place to explain the impression that the initial state is "fine tune", and why this is not a problem.

The position she takes I think is that any implications one might draw about how the correlations were constructed is speculative and irrelevant. All that matters is that the correlations existed.

She is right that the fine tuning argument presupposes a fictional space of possible parameters, and there is no concrete way to assign a meaningful probability (e.g. that things exist as they do, rather than some other hypothetical way) using such a fictional space.

Ultimately it seems to me that she is saying that we should just assume that the correlations exist somehow, and then just calculate.

 

[Morbert]

Ultimately it seems to me that she is saying that we should just assume that the correlations exist somehow, and then just calculate.

This seems like a peculiar prescription on her part, considering we can just calculate even without assuming correlated hidden variables. She's presenting a just so story, but she needs to sell it too.

 

[J O Linton]

I wonder if I could respectfully redirect your attention back to the OP? The original question was: in the context of the experiment described in #1, how would adherents of the standard interpretation, the MWI, the Pilot wave interpretation and, we may now add, superdeterminism respond to the charge that their interpretation involved 'spooky action at a distance (whatever Einstein meant by that)?

 

[Lord Jestocost]

Adherents of the standard interpretation wouldn't see any reason to respond to the charge that their interpretation involved ‘spooky action at a distance’. Here is a fundamental error in thinking. The world is not classical, and ideas as ‘non-locality’ or ‘spooky action at a distance’ are not needed because the world is quantum mechanical. Murray Gell-Mann puts it in “The Quark and the Jaguar” (chapter: “Quantum Mechanics and flapdoodle”) in the following way:

“The label ‘nonlocal’ applied by some physicists to quantum-mechanical phenomena like the EPRB effect is thus an abuse of language. What they mean is that if interpreted classically in terms of hidden variables, the result would indicate nonlocality, but of course such a classical interpretation is wrong.” [bold by LJ]

One should thus avoid the term ‘quantum non-locality’ and not mix it up with ‘quantum non-separability’, which is indeed rooted in the way the quantum formalism represents systems and sub-systems.

 

[J O Linton]

In a letter to Born Einstein objected to the standard (statistical) interpretation with the words: " I cannot seriously believe in it because the theory cannot be reconciled with the idea that physics should represent a reality in time and space, free from spooky action at a distance" so he obviously thought that the interpretation required SAAAD. I agree, however, that the 'shut up and calculate' brigade would simply ignore the charge. But simply ignoring the charge doesn't make it go away. On any reasonably realistic interpretation, when photon A arrives at P1 and the wavefunction collapses, the subsequent behaviour of photon B is irrevocably altered. How is that not SAAAD?

Since SAAAD (if it happens at all) only occurs during the 'collapse of the wave function' I think we can take it that adherents of MWI would refute the charge on the basis that decoherence simply decrees that after A has encountered P1, the multitude of possibilities that existed in a superposition of states has now simply reduced to two possibilities, both of which are realized. Would you agree?

 

[gentzen]

She is right that the fine tuning argument presupposes a fictional space of possible parameters, and there is no concrete way to assign a meaningful probability (e.g. that things exist as they do, rather than some other hypothetical way) using such a fictional space.

She is right on the one hand, but she also undercuts her own explanation by saying: "Superdeterminism is exactly as deterministic as plain old vanilla determinism." There is a difference between determinism and superdeterminism, and denying that difference is not helpful.

This seems like a peculiar prescription on her part, considering we can just calculate even without assuming correlated hidden variables. She's presenting a just so story, but she needs to sell it too.

Exactly, she needs to sell it.

I wonder if I could respectfully redirect your attention back to the OP?

Good point. I am not especially keen on discussing superdeterminism anyway, since I learned already that it is very easy to get myself into an uncomfortable position.

 

[PeterDonis]

after A has encountered P1, the multitude of possibilities that existed in a superposition of states

What do you mean by "the multitude of possibilities that existed in a superposition of states" here?

 

[PeterDonis]

What do you mean by "the multitude of possibilities that existed in a superposition of states" here?

@J O Linton if what you mean is this from the OP...

When the two photons leave the source they are in a superposition of an infinite number of states with their polarisation planes in all possible directions (but always at right angles to each other)

...then your description is incorrect. The initial entangled two-photon state is not a superposition of an infinite number of states. It's just one state. The different possible polarization planes are different ways we can describe the one state the photon is in, but those are just different descriptions. The only polarization directions that are physically meaningful are the ones we actually choose to measure with polarizers.

 

[J O Linton]

I think I see what you mean. What you are saying is that, unlike a true superposition of states which we could interrogate to find out which state the system collapses into, we cannot ask the photon, 'what is your angle of polarisation?' - all we can do is ask 'are you vertical?', or whatever.

So what is the best language to use to describe the state of polarization of the entangled photons immediately after they have left the source?

 

[PeterDonis]

unlike a true superposition of states

There is no such thing as "a true superposition of states". Superposition is always basis dependent; we can always find a basis in which the given state is one of the basis states.

which we could interrogate to find out which state the system collapses into

There is never any way to ask any photon "which direction are you polarized in" where the answer could be any direction whatever. For any photon, all you can do is pick a direction for your polarizer and see if the photon passes through or not.

what is the best language to use to describe the state of polarization of the entangled photons immediately after they have left the source?

An entangled state of two photons with total spin zero.

 

[DrChinese]

One should thus avoid the term ‘quantum non-locality’ and not mix it up with ‘quantum non-separability’, which is indeed rooted in the way the quantum formalism represents systems and sub-systems.

Or you could just say that "quantum non-locality" is the correct term to describe the set of phenomena that is observed in line with the predictions of QM. Note that this is an umbrella for not only apparent non-locality, and apparent "quantum non-separability", but also what might be called "quantum non-temporal" (there is no widely accepted term for this). An entangled system of 2 particles (say photons) does not require that they ever overlapped in any region of spacetime (they were always separated), and in fact need not have ever co-existed (ergo the "non-temporal" entanglement).

The rationale for using the phrase "quantum non-locality" is that it is already in widespread use to include the umbrella of observed entangled phenomena.