Changes

The '''General Theory of Relativity''' is an extension of [[Special theory of relativity|special relativity]], dealing with curved coordinate systems, accelerating frames of reference, curvilinear motion, and curvature of spacetime itself.  It could be said that general relativity is to special relativity as vector calculus is to vector algebra.  General relativity is best known for its formulation of gravity as a fictitious force arising from the curvature of spacetime.  In fact, "general relativity" and "Einstein's formulation of gravity" are nearly synonymous in many people's minds.

The '''General Theory of Relativity''' is an extension of [[Special theory of relativity|special relativity]], dealing with curved coordinate systems, accelerating frames of reference, curvilinear motion, and curvature of spacetime itself.  It could be said that general relativity is to special relativity as vector calculus is to vector algebra.  General relativity is best known for its formulation of gravity as a fictitious force arising from the curvature of spacetime.  In fact, "general relativity" and "Einstein's formulation of gravity" are nearly synonymous in many people's minds.

[[Image:600px-Albert Einstein Head.jpg|thumbnail|right|200px|

[[Image:Cvx432.jpg|right|thumbnail|right|200px|Bernhard Riemann created the mathematical underpinnings of differential geometry on curved (non-Euclidean) manifolds, that are the basis for General Relativity.]]

*"I do not share the crusading spirit of the professional [[Atheism|atheist]] whose fervor is mostly due to a painful act of liberation from the fetters of religious indoctrination received in youth. I prefer an attitude of humility corresponding to the weakness of our intellectual understanding of nature and of our own being." - [[Albert Einstein]]<ref name="Isaacson390">Isaacson, Walter (2008). [http://books.google.com/books?id=cdxWNE7NY6QC&pg=PT390 ''Einstein: His Life and Universe''] (New York: Simon and Schuster), p. 390.  Retrieved from GoogleBooks archive on February 19, 2015.</ref>]]

The general theory of relativity was first published by Marcel Grossman in 1913 and [[David Hilbert]] and [[Albert Einstein]] in 1916.

The general theory of relativity was first published by Marcel Grossman in 1913 and [[David Hilbert]] and [[Albert Einstein]] in 1916.

However, "even though General Relativity has passed many tests, most physicists don’t believe it is ultimately correct because it conflicts with [[quantum mechanics]]." [http://newsdesk.org/2010/08/conservapedia-calls-theory-of-relativity-a-liberal-conspiracy/]

However, "even though General Relativity has passed many tests, most physicists don’t believe it is ultimately correct because it conflicts with [[quantum mechanics]]." [http://newsdesk.org/2010/08/conservapedia-calls-theory-of-relativity-a-liberal-conspiracy/]

General relativity, like [[quantum mechanics]] (the other of the two theories comprising "modern physics") both have reputations for being notoriously complicated and difficult to understand.  In fact, in the early decades of the 20^th century, general relativity had a sort of cult status in this regard.  General relativity and quantum mechanics are both advanced college-level and postgraduate level topics.  Hence this article can't possibly give a comprehensive explanation of general relativity at the expert level.  But we will attempt to give a rough outline, for lay people, of the general relativistic formulation of gravity.

General relativity, like [[quantum mechanics]] (the other of the two theories comprising "modern physics") both have reputations for being notoriously complicated and difficult to understand.  In fact, in the early decades of the 20th century, general relativity had a sort of cult status in this regard.  General relativity and quantum mechanics are both advanced college-level and postgraduate level topics.  Hence this article can't possibly give a comprehensive explanation of general relativity at the expert level.  But we will attempt to give a rough outline, for lay people, of the general relativistic formulation of gravity.

In the weak field approximation, where velocities of moving objects are low and gravitational fields are not very severe, the theory of general relativity is said to ''reduce to'' the law of universal gravitation. That is to say, under those circumstances the equations of general relativity are mathematically equivalent to the equations of Newtonian gravitation.

In the weak field approximation, where velocities of moving objects are low and gravitational fields are not very severe, the theory of general relativity is said to ''reduce to'' the law of universal gravitation. That is to say, under those circumstances the equations of general relativity are mathematically equivalent to the equations of Newtonian gravitation.

''Main article:'' [[Gravitational lensing]]

''Main article:'' [[Gravitational lensing]]

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.

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>

{{Relativity}}

{{Relativity}}

==External Links==

==External links==

*Einstein, Albert (1916), [http://www.alberteinstein.info/gallery/pdf/CP6Doc30_English_pp146-200.pdf "The Foundation of the General Theory of Relativity"] (PDF), Annalen der Physik 49

*Einstein, Albert (1916), [http://www.alberteinstein.info/gallery/pdf/CP6Doc30_English_pp146-200.pdf "The Foundation of the General Theory of Relativity"] (PDF), Annalen der Physik 49

*[http://www.rareuniverse.org/general_science/general_relativity.html A simple explanation of General Relativity]

*[http://www.rareuniverse.org/general_science/general_relativity.html A simple explanation of General Relativity]