Principle of locality
In physics, the principle of locality is that distant objects cannot have direct influence on one another: an object is influenced directly only by its immediate surroundings. This was stated as follows by Albert Einstein in a 1948 article:
The following idea characterises the relative independence of objects far apart in space (A and B): external influence on A has no direct influence on B; this is known as the Principle of Local Action, which is used consistently only in field theory. If this axiom were to be completely abolished, the idea of the existence of quasienclosed systems, and thereby the postulation of laws which can be checked empirically in the accepted sense, would become impossible.
This principle is challenged by quantum mechanics: the locality principle appears to be violated by Bell's inequality. See also EPR paradox, quantum entanglement.
In computer science, the principle of locality is sometimes used as an alternative name for locality of reference.