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lkm0 • yesterday at 11:04 AM • 1 reply • view on HN

One of the "coping mechanisms" is to say that information cannot travel faster than light, even if entanglement is propagated instantaneously and measurement acts faster than light. If Alice and Bob share an entangled pair of spins and Alice measures it, Bob has gained no information until Alice communicates (sublight speed) her result. No new information is shared at measurement time. This is known as the no-communication theorem.


Replies

antihipocrat • today at 6:37 AM

I don't think that's correct? Alice knows immediately what Bob's result is going to be as soon as she measure's it. The travel faster than light part that many people (including Einstein) take/took issue with includes this as an effect. More generally put is that if spin is in a superposition until measurement collapses it into a known quantity, then the result of the collapse itself is somehow propagated to the other entangled particle instantaneously.