Editing No-communication theorem (section)

{{Short description|Principle in quantum information theory}}
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{{Use American English|date=January 2019}}
In [[physics]], the '''no-communication theorem''' (also referred to as the '''no-signaling principle''') is a no-go theorem in [[Quantum information|quantum information theory]]. It asserts that during the measurement of an [[Quantum entanglement|entangled quantum state]], it is impossible for one observer to transmit information to another observer, regardless of their spatial separation. This conclusion preserves the principle of causality in [[quantum mechanics]] and ensures that information transfer does not violate special relativity by exceeding the speed of light.

The theorem is significant because quantum entanglement creates correlations between distant events that might initially appear to enable faster-than-light communication. The no-communication theorem establishes conditions under which such transmission is impossible, thus resolving paradoxes like the [[Einstein–Podolsky–Rosen paradox|Einstein-Podolsky-Rosen (EPR) paradox]] and addressing the violations of local realism observed in [[Bell's theorem]]. Specifically, it demonstrates that the failure of local realism does not imply the existence of "spooky action at a distance," a phrase originally coined by Einstein.