Locality is a feature of the world that is suggested by the experience that local causes produce local effects. In quantum mechanics, however, the EPR Paradox conceived of widely separated situations entangled by virtue of their quantum histories, and it is possible for a quantum measurement to have a nonlocal effect. It has sometimes been suggested that nonlocality might form a basis for telepathy or some form of faster-than-light signaling or travel. However, it can be shown that within quantum mechanics it is not possible to transfer information faster than the speed of light by exploiting quantum nonlocality. No two quantum mechanical measurements can be connected to each other by a faster-than-light signal.
Albert Einstein's (1879–1955) General Theory of Relativity requires local behavior in ways that Newton's theory of gravity does not. In Isaac Newton's (1642–1727) theory there exist mysterious gravitational forces that act instantaneously over unlimited distances in space (for example, the gravitational force of the sun on the Earth). In Einstein's theory there are no instantaneous nonlocal gravitational forces. Everything acts locally. The presence of mass or energy in space makes space curved, and all bodies move in response to the local curvature of space that they encounter locally, not in response to long-range, nonlocal forces of attraction.
Locality played an important role in the development of Western science. Most early science in the West was nonholistic in the sense that it maintained that the world could be analyzed locally without having to understand the whole of the universe. By contrast, Eastern holistic philosophies were handicapped in the development of a successful working theory of nature because they held strongly to a holistic view of the world. There has been debate about the resonance between the holistic nature of some parts of modern physics, notably quantum mechanics, chaos, and complexity, and early Eastern holistic philosophies. It is clear that a local, nonholistic, largely reductionist outlook is advantageous in beginning a successful scientific enterprise. While there undoubtedly are holistic aspects of the world, they are most effectively understood after having understood the local aspects.
See also EPR Paradox; Physics, Quantum; Relativity, General Theory of
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john d. barrow
lo·cal·i·ty / lōˈkalətē/ • n. (pl. -ties) the position or site of something: the rock's size and locality. ∎ an area or neighborhood, esp. as regarded as a place occupied by certain people or as the scene of particular activities: the results of other schools in the locality a working-class locality.