# Are quantum-entangled particles affected by relativistic speeds? [duplicate]

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In my answer to a recent question on World Building, I suggested that quantum-entangled particles would be a good way for ships traveling at relativistic speeds to communicate. My understanding is that quantum-entanglement allows for instantaneous action at a distance.

Is this accurate? Do quantum-entangled particles, when flipped, effect an immediate/instantaneous flip on the other side? Do relativistic speeds affect quantum-entangled particles in their speed of "communication?"

## marked as duplicate by ACuriousMind♦, Brandon Enright, BMS, Danu, Kyle KanosDec 12 '14 at 2:15

• Quantum entanglement is the product of a local theory, and hence will not permit information to be transmitted faster than light. This is a duplicate of, e.g., physics.stackexchange.com/q/78118/50583 – ACuriousMind Dec 11 '14 at 23:15
• Quantum entanglement is possibly the most extreme example of "correlation is not causation" that we know about. It produces pure correlation without any causal relationship, whatsoever. As such it plays very nicely into our sense for paradoxes, which is basically another way of saying that the human mind is very stubborn to accept facts that contradict "obvious" but fundamentally false lines of intuitive reasoning. – CuriousOne Dec 11 '14 at 23:35

$$\frac{\lvert x \rangle \lvert x \rangle + \lvert y \rangle \lvert y \rangle}{\sqrt{2}}$$