> Locality is the same as saying causation is limited to speed of light Nope. When two qbits are entangled, operations on one affect the other instantaneously.

> Locality is the same as saying causation is limited to speed of light Nope. When two qbits are entangled, operations on one affect the other instantaneously. This breaks locality. However, it does not break causality - we cannot get any classical information from one qbit's frame to the other. See the No-communication theorem: https://en.wikipedia.org/wiki/No-communication_theorem https://en.wikipedia.org/wiki/No-communication_theorem You can have non-locality without time travel, or breaking causality. If I entangle two qbits, give you one, and we both go to opposite ends of the universe, then when I measure my qbit I'll know yours instantly collapsed to the same value. However, all we've done is created a shared random number generator. I can't communicate anything to you. One might be tempted to think - well, why do we believe entanglement is a non-local phenomenon? Surely the qbits just decided at the time of entanglement how they would collapse, then remembered that? No. That is called hidden variable theory, which has been disproved. Entanglement breaks locality, but not causality.