Nerd alert! -more spooky Quantum stuff

[polymath257]

"Why" is a question that has little relevance in the sciences, which are used to describe "how" things work, to as close an approximation as we can measure. Science isn't the correct venue for "why" questions.

Which is why our man Einstein said those immortal words. (spooky action at a distance)
But he was wrong by arguing the moon doesn't disappear when we're not looking at it, and God doesn't play dice. (response to Bohr)
Even he was conflating the macro world (Newtonian) with the quantum world. The "why" played havoc on his mind.

Einstein was demonstrably wrong about what happens to entangled particles. He thought that the EPR paradox showed something that could not be the case in reality. And yet, we have done experiments that show *exactly* that phenomenon does happen and in a way consistent with QM.

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I agree with Einstein that God does not play dice.

It is said that there are no hidden variables. But to me that is just science working within its own framework and not making statements outside itself. As it shouldn't.

The truth is that absence of evidence is not evidence of absence. And that in response to "there are no hidden variables", when wrongly taken as a truth beyond the scope of science, I would simply ask: how would we know?

We know because of the violation of Bell's inequalities. ANY hidden variable theory that is local and realist obeys those inequalities. But, by actual observation, the universe does not.

Einstein was wrong: the universe is inherently probabilistic at base.

Quantum deterministic causation that is far too complex to be examinable by us is indistinguishable from quantum acausality.

Scientific theories simply don't make statements outside their scope ... if something is unfalsifiable science doesn't claim to have absolute knowledge that the unfalsifiable thing is impossible---science just says it isn't real *in scientific terms*. But that's only one way of saying it. Other scientists would say that it isn't knowable by science but still may or may not be real. It depends. As there are scientists who are scientific pragmatists who believe in methodological scientific realism but don't believe in metaphysical scientific realism---they believe that science deals with knowledge of reality rather than with reality itself.

What's more, there are also deterministic models of quantum mechanics too. Not all quantum physicists would agree that God does not play dice (metaphorically speaking). I believe that the model of QM that Sean Carroll holds to is, if I'm not mistaken, a deterministic one.

The problem with those deterministic models (Bohmian mechanics) is that they only work for classical quantum theory. Once you go to the special relativistic side (quantum field theories), they fail miserably. So, effects like spin and anti-matter are not explained by such theories.

Also, Bohmian mechanics violates the 'local' aspect: there is faster then light signaling, which in a relativistic situation means reverse-time causality.

Also, there is a difference between actual literal indeterminism and acausality on the one hand and indeterminism in the sense of indeterminancy, or in other words, unpredictability and acausality to mean science's inability to find any causes at the quantum level, on the other hand.

To me it's just an error of mistaking the map for the territory. Science is a map rather than a territory. But it's not just a map. It's the best map we have! By far. But it's still a map.

Agreed, but we can, and have, eliminated a whole class of hidden variable theories (those that are both local and realist) because of the failure of Bell's inequalities.

That means, ultimately, that any hidden variable model has to have attributes even stranger than quantum mechanics.

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By "observer", some concluded, fallaciously, that it meant "conscious" observer.

There's no such thing as a non-conscious observer. So either it's not really an observer at all or it's a conscious observer.

A Geiger counter is enough to 'collapse the wave function', but is not usually regarded as being conscious. The *vast* majority of modern measurements are not done by conscious observers.

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So. We agree with "Any interaction counts as an 'Observation'." ? Cool.

Perhaps in one sense. Perhaps in both senses. But my point is that at least one sense of observation requires consciousness and that was the sort of observation I was interested in.

My own belief is that everything requires conscious observation in some form.

And that belief is wrong when it comes to issues of wave function collapse in quantum mechanics.

Technically, what is required is an 'irreversible interaction'. It is the irreversibility that 'collapses the wave function'. Furthermore, this type of irreversibility can happen by interaction with almost any macroscopic object (and even many microscopic ones).

This whole aspect was elucidated in the 1990's under the name of 'decoherence theory' and has been verified by observation. For example, maintaining coherence is one of the big challenges in making quantum computers: *any* significant interaction tends to collapse the wave function and destroy the calculation.