General relativity

General relativity (GR) or general relativity theory (GRT) is a geometrical theory of gravitation and cosmology published by Albert Einstein in 1915. In this theory:

Related Topics:
General relativity - Geometrical - Theory - Gravitation - Cosmology - Albert Einstein - 1915

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• Spacetime is treated as a curved 4-dimensional Lorentzian manifold;
• Spacetime is curved by the presence of mass/energy and momentum (or stress-energy) within it;
• The relationship between stress-energy and the curvature of spacetime is governed by the Einstein field equations; and
• Inertial motion occurs along timelike and null geodesics of spacetime.

In general relativity, gravitation is not due to a force. Instead, phenomena that in classical mechanics are ascribed to the action of the force of gravity (such as freefall, orbital motion, and spacecraft trajectories) are taken in general relativity to represent inertial motion in a curved spacetime. So what people standing on the surface of the Earth perceive as the 'force of gravity' is a result of their undergoing a continuous physical acceleration caused by the mechanical resistance of the surface that they are standing on. One of the defining features of general relativity is the idea that gravitational 'force' is replaced by geometry.

Related Topics:
Gravitation - ^[1] - Force - Classical mechanics - Gravity - Freefall - Orbit - Spacecraft - Trajectories - Continuous physical acceleration

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General relativity: Overview ►