News tagged with general relativity
Scientists gear up to take a picture of a black hole
On Wednesday, Jan. 18, astronomers, physicists and scientists from related fields will convene in Tucson, Ariz. from across the world to discuss an endeavor that only a few years ago would have been regarded as nothing less ...
Jan 14, 2012 |
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Physicists propose test for loop quantum gravity
(PhysOrg.com) -- As a quantum theory of gravity, loop quantum gravity could potentially solve one of the biggest problems in physics: reconciling general relativity and quantum mechanics. But like all tentative ...
String theory researchers simulate big-bang on supercomputer
(PhysOrg.com) -- A trio of Japanese physicists have applied a reformulation of string theory, called IIB, whereby matrices are used to describe the properties of the physical universe, on a supercomputer, to effectively sho ...
A serendipitous gravitational lens
(PhysOrg.com) -- The path traveled by a light beam will bend in the presence of matter. This remarkable prediction, reached by Einstein in his theory of general relativity, was confirmed by observations of ...
Nov 21, 2011 |
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One clock with two times: When quantum mechanics meets general relativity
The unification of quantum mechanics and Einstein's general relativity is one of the most exciting and still open questions in modern physics. General relativity, the joint theory of gravity, space and time ...
Oct 19, 2011 |
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Why Einstein was wrong about being wrong
If you want to get your mind around the research that won three astronomers the Nobel Prize in physics last week, it helps to think of the universe as a lump of dough - raisin-bread dough, to be precise - mixed, kneaded and ...
Oct 14, 2011 |
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Astrophysicists find evidence of black holes' destruction of stars
Astrophysicists have found evidence of black holes destroying stars, a long-sought phenomenon that provides a new window into general relativity. The research, reported in the latest issue of the Astrophysical Jo ...
Oct 11, 2011 |
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Challenging Einstein is usually a losing venture
(AP) -- Betting against Einstein and his theory of relativity is a way to go broke. For more than a century, everyone from physicists to the Nazi Party - which encouraged the publication of the tract "One ...
Sep 23, 2011 |
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Metamaterials used to mimic the Big Crunch
Spacetime analogs is an emerging field of physics in which scientists investigate systems having mathematical links with general relativity, and test their theories about the early behavior of the universe. The latest in ...
Evolved stars locked in fatalistic dance
White dwarfs are the burned-out cores of stars like our Sun. Astronomers have discovered a pair of white dwarfs spiraling into one another at breakneck speeds. Today, these white dwarfs are so near they make ...
Jul 13, 2011 |
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Bright sparks among 'Asia's Nobel Prize' winners
Two scientists who are probing the brightest flashes in the universe were Tuesday named among the winners of the Shaw Prize, the $1 million award known as the Nobel Prize of the east.
Jun 07, 2011 |
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Mystery force may be due to mirrors
Portuguese physicists report that they have identified the unknown force whose influence on outward bound interplanetary space probes has puzzled scientists since 1998. ...
May 05, 2011 |
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Antigravity could replace dark energy as cause of Universe's expansion
Since the late 20th century, astronomers have been aware of data that suggest the universe is not only expanding, but expanding at an accelerating rate. According to the currently accepted model, this accelerated ...
Apr 18, 2011 |
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Antimatter gravity could explain Universe's expansion
(PhysOrg.com) -- In 1998, scientists discovered that the Universe is expanding at an accelerating rate. Currently, the most widely accepted explanation for this observation is the presence of an unidentified ...
Big Bang simulated in metamaterial shows time travel is impossible
(PhysOrg.com) -- By observing the way that light moves inside a metamaterial, researchers have reconstructed how spacetime has expanded since the Big Bang. The results provide a better understanding of why ...
General relativity
General relativity or the general theory of relativity is the geometric theory of gravitation published by Albert Einstein in 1916. It is the current description of gravitation in modern physics. It unifies special relativity and Newton's law of universal gravitation, and describes gravity as a geometric property of space and time, or spacetime. In particular, the curvature of spacetime is directly related to the four-momentum (mass-energy and linear momentum) of whatever matter and radiation are present. The relation is specified by the Einstein field equations, a system of partial differential equations.
Many 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, the gravitational redshift of light, and the gravitational time delay. General relativity's predictions 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. It points towards 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 evidence that such stellar black holes as well as more massive varieties of black hole are responsible for the intense radiation emitted by certain types of astronomical objects such as active galactic nuclei or microquasars. The bending of light by gravity can lead to the phenomenon of gravitational lensing, where 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 measured indirectly; a direct measurement is the aim of projects such as LIGO. In addition, general relativity is the basis of current cosmological models of a consistently expanding universe.
For more information about General relativity, read the full article at
Wikipedia.
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