**General relativity**, or the **general theory of relativity**, is the geometric theory of gravitation published by Albert Einstein in 1916 and the current description of gravitation in modern physics. General relativity generalises special relativity and Newton's law of universal gravitation, providing a unified description of gravity as a geometric property of space and time, or spacetime. In particular, the curvature of spacetime is directly related to the energy and momentum of whatever matter and radiation are present. The relation is specified by the Einstein field equations, a system of partial differential equations.

Some predictions of general relativity differ significantly from those of classical physics, especially concerning the passage of time, the geometry of space, the motion of bodies in free fall, and the propagation of light. Examples of such differences include gravitational time dilation, gravitational lensing, the gravitational redshift of light, and the gravitational time delay. The predictions of general relativity have been confirmed in all observations and experiments to date. Although general relativity is not the only relativistic theory of gravity, it is the simplest theory that is consistent with experimental data. However, unanswered questions remain, the most fundamental being how general relativity can be reconciled with the laws of quantum physics to produce a complete and self-consistent theory of quantum gravity.

Einstein's theory has important astrophysical implications. For example, it implies the existence of black holes—regions of space in which space and time are distorted in such a way that nothing, not even light, can escape—as an end-state for massive stars. There is ample evidence that the intense radiation emitted by certain kinds of astronomical objects is due to black holes; for example, microquasars and active galactic nuclei result from the presence of stellar black holes and black holes of a much more massive type, respectively. The bending of light by gravity can lead to the phenomenon of gravitational lensing, in which multiple images of the same distant astronomical object are visible in the sky. General relativity also predicts the existence of gravitational waves, which have since been observed indirectly; a direct measurement is the aim of projects such as LIGO and NASA/ESA Laser Interferometer Space Antenna and various pulsar timing arrays. In addition, general relativity is the basis of current cosmological models of a consistently expanding universe.

Read more about General Relativity: History, From Classical Mechanics To General Relativity, Definition and Basic Applications, Consequences of Einstein's Theory, Relationship With Quantum Theory, Current Status

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**General Relativity**and Quantum Mechanics

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**General relativity**typically deals with situations involving large mass objects in fairly large regions of spacetime whereas quantum mechanics is generally ... congruence is that, at Planck scale (a fundamental small unit of length) lengths,

**general relativity**predicts a smooth, flowing surface, while quantum mechanics predicts a random, warped surface, neither of which are ...

... are solutions of the field equations of

**general relativity**which describe "warp drives" (such as the Alcubierre metric) and stable, traversable wormholes ... of the stress–energy tensor field (see exact solutions in

**general relativity**) ...

**General relativity**does not constrain the geometry of spacetime unless outside constraints are placed on the stress–energy tensor ...

... This is "special

**relativity**" as usually understood ... This is non-gravitational physics plus

**general**covariance ... This is the sense in which "special

**relativity**" can handle accelerated frames ...

... Stanley Deser is an American physicist known for his contributions to

**general relativity**... In the context of

**general relativity**, he is best known for his development (with Richard Arnowitt and Charles Misner) of the ADM formalism, roughly speaking a way of describing spacetime as space ... like energy or, equivalently, mass (so-called ADM mass/energy) which, in

**general relativity**, is not trivial at all ...

**General Relativity**- Current Status

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**General relativity**has emerged as a highly successful model of gravitation and cosmology, which has so far passed many unambiguous observational and ... Even taken as is,

**general relativity**is rich with possibilities for further exploration ... More than ninety years after its publication,

**general relativity**remains a highly active area of research ...

### Famous quotes containing the words relativity and/or general:

“By an application of the theory of *relativity* to the taste of readers, to-day in Germany I am called a German man of science, and in England I am represented as a Swiss Jew. If I come to be regarded as a bête noire the descriptions will be reversed, and I shall become a Swiss Jew for the Germans and a German man of science for the English!”

—Albert Einstein (1879–1955)

“A writer who writes, “I am alone” ... can be considered rather comical. It is comical for a man to recognize his solitude by addressing a reader and by using methods that prevent the individual from being alone. The word alone is just as *general* as the word bread. To pronounce it is to summon to oneself the presence of everything the word excludes.”

—Maurice Blanchot (b. 1907)