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by tbrownaw 661 days ago
> maintained a kind of polarization state between each other over a long distance, where the observation of one of them caused a state change at the other "end". this idea of remote causality

Operating on one half of an entangled pair does not transmit information to the other half. Therefore, the is no action or causation. Choices of vocabulary which imply otherwise are incorrect.

It also doesn't work by "hidden variables" - there isn't some secret value which we just don't know yet. So while it's probably least inaccurate to describe what happens in terms of our knowledge of the remote particle changing, is closer to the new facts we learned coming into existence as we learn them, rather than discovering an existing fact. Except that's also not quite right (information can never be created or destroyed).

1 comments

Whether there is any kind of action on the entangled counterpart is not actually answered by quantum mechanics, and depends on the interpretation. For example, in the Copenhagen interpretation there is an action (measuring one half of the pair causes the others waveform to instantly collapse), but in the Many Worlds interpretation there is no causal action, because observation is just a new entanglement between the observer and the entangled pair system.
The math is clear that there is no information transfer.

The various interpretations are ways of trying to map what actually happens onto easily-understandable descriptions using standard classical-world vocabulary, which doesn't work very well because QM has fundamental differences from the macroscopic world that we live in and drive our language from. Where they disagree with eachother or with the math is because those mappings aren't perfect.

Just because there is no information transfer does not mean there is no action, it just means that this action does not break causality.
Redefining words like that makes the resulting explanations misleading outside the narrow circle who already know enough to be aware of and understand the redefinition.