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==Exact Solutions in General Relativity==

==Exact Solutions in General Relativity==

==Tests of General Relativity==

==Consequences and Tests of General Relativity==

General relativity provides one explanation for the precession of Mercury's perihelion, which was moving at a different speed than that predicted by a simple application of Newton's law of universal gravitation.  (Previous scientists had attempted to explain it by the gravitational pull of a hypothetical planet inside Mercury's orbit, which they called [[Vulcan]].  This could also be explained by altering the precise inverse-square relation of Newtonian gravity to distance, but that was disfavored by mathematicians due to its inelegance in integrating.)

General relativity provides one explanation for the precession of Mercury's perihelion, which was moving at a different speed than that predicted by a simple application of Newton's law of universal gravitation.  (Previous scientists had attempted to explain it by the gravitational pull of a hypothetical planet inside Mercury's orbit, which they called [[Vulcan]].  This could also be explained by altering the precise inverse-square relation of Newtonian gravity to distance, but that was disfavored by mathematicians due to its inelegance in integrating.)

British historian Paul Johnson declares the turning point in the acceptance of general relativity to have been when Sir [[Arthur Eddington]], an esteemed English astronomer, ventured out on a boat off Africa in 1919 with a local Army unit to observe the bending of starlight around the sun during a total [[solar eclipse]]. General relativity predicted that the light from the stars would be bent due to passing close to the sun.  (A smaller degree of bending could also be consistent with Newton's theory, if one hypothesized light to consist of particles.  However, that [[particle theory of light]] had gone out of favor previously.)  Eddington detected a bending of light, but his range of error overlapped both Einstein's and Newton's predictions.  Upon his return to England, Eddington declared that his observations proven the theory of relativity.  His experiment was later confirmed by more rigorous experiments, such as those performed by the [[Hubble Space Telescope]] <ref>[http://www.spaceimages.com/gravlen.html Hubble Gravitational Lens Photo]</ref><ref> [http://csep10.phys.utk.edu/astr162/lect/galaxies/lensing.html Gravitational Lensing] </ref><ref>[http://www.iam.ubc.ca/~newbury/lenses/glgallery.html]</ref>.  Lorentz has this to say on the discrepancies between the empirical eclipse data and Einstein's predictions.

General relativity predicts that the path of light will be distorted when it passes near a massive object.  In 1919, Sir [[Arthur Eddington]], an esteemed English astronomer, used this to test general relativity by observing the bending of starlight around the sun during a total [[solar eclipse]].<ref>Paul Johnson, British historian</ref>.  (A smaller degree of bending could also be consistent with Newton's theory, if one hypothesized light to consist of particles.  However, that [[particle theory of light]] had gone out of favor previously.)  Eddington detected a bending of light, but his range of error overlapped both Einstein's and Newton's predictions.  Upon his return to England, Eddington declared that his observations proven the theory of relativity.  His experiment was later confirmed by more rigorous experiments, such as those performed by the [[Hubble Space Telescope]] <ref>[http://www.spaceimages.com/gravlen.html Hubble Gravitational Lens Photo]</ref><ref> [http://csep10.phys.utk.edu/astr162/lect/galaxies/lensing.html Gravitational Lensing] </ref><ref>[http://www.iam.ubc.ca/~newbury/lenses/glgallery.html]</ref>.  Lorentz has this to say on the discrepancies between the empirical eclipse data and Einstein's predictions.

::''It indeed seems that the discrepancies may be ascribed to faults in observations, which supposition is supported by the fact that the observations at Prince's Island, which, it is true, did not turn out quite as well as those mentioned above, gave the result, of 1.64, somewhat lower than Einstein's figure.''<ref>Lorentz, H.A. [http://ia331314.us.archive.org/2/items/theeinsteintheor11335gut/11335-h/11335-h.htm The Einstein Theory of Relativity]</ref>

::''It indeed seems that the discrepancies may be ascribed to faults in observations, which supposition is supported by the fact that the observations at Prince's Island, which, it is true, did not turn out quite as well as those mentioned above, gave the result, of 1.64, somewhat lower than Einstein's figure.''<ref>Lorentz, H.A. [http://ia331314.us.archive.org/2/items/theeinsteintheor11335gut/11335-h/11335-h.htm The Einstein Theory of Relativity]</ref>

 

==Relation to Special Relativity==

==Relation to Special Relativity==