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=Einstein's Theory of Relativity=

= = //Albert Einstein's Theory of Relativity consisted of two sub-theories, general relativity and special relativity. General relativity proposed that gravity, as well as motion, can affect the intervals of time and of space. Special relativity proposed that distance and time are not absolute.

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In November, 1919, Albert Einstein became famous, thanks to a solar eclipse. An experiment he had been working on confirmed that light rays from distant stars were deflected by gravity of the sun in the exact amount predicted in his theory of gravity, general relativity. General relativity was the first major new theory of gravity since Newton 250 years earlier. General relativity was first published in 1915, which came after Einstein's theory of special relativity. Special relativity proposed that distance and time are not absolute. The possibility of black holes were predicted based off of the theory of general relativity. A black hole is a region of space whose attractive gravitational force is so intense that no matter, light, or communication of any kind can escape. The possibility that stars could collapse to form black holes was first theoretically "discovered" in 1939 by J. Robert Oppenheimer and Hartland Snyder, who were manipulating the equations of Einstein's general relativity (Lightman).



General relativity proposed that gravity, as well as motion, can affect the intervals of time and of space. The key idea of general relativity, called the equivalence principle, is that gravity pulling in one direction is completely equivalent to an acceleration in the opposite direction. A car accelerating forwards feels just like sideways gravity pushing you back against your seat. An elevator accelerating upwards feels just like gravity pushing you into the floor (Lightman).

General relativity has to deal with black holes and the universe as a whole. A black hole is a region of space whose attractive gravitational force is so intense that no matter, light, or communication of any kind can escape (Lightman). It is believed that black holes form from collapsed stars. Every star must eventually exhaust its nuclear fuel. When that occurs, its unbalanced self-gravitational attraction causes it to collapse. According to theory, if a burned-out star has a mass larger than about three times the mass of our sun, no amount of additional pressure can stave off total gravitational collapse. The star collapses to form a black hole (Lightman).



Beginning in 1917, Einstein and others applied general relativity to the structure and evolution of the universe as a whole. The leading cosmological theory, called the big bang theory, was formulated in 1922 by the Russian mathematician and meteorologist Alexander Friedmann (Lightman). One of the most stunning outcomes of the big bang theory was that it was predicted that the earth was ten billion years old. This was obtained by calculating the rate at which distant galaxies are flying away from each other. According to the big bang theory, the universe may keep expanding forever, if its inward gravity is not sufficiently strong to counterbalance the outward motion of galaxies, or it may reach a maximum point of expansion and then start collapsing, growing denser and denser, gradually disrupting galaxies, stars, planets, people, and eventually even individual atoms (Lightman).

Albert Einstein's Theory of Relativity consisted of two theories, general relativity and special relativity. These theories helped gain further understanding of black holes and the study of the universe as a whole. Quoted by Alan Lightman, "If it were not for Einstein, several decades might have passed before another physicist worked out the concepts and mathematics of general relativity." I believe that eventually we will know how and when our universe will begin to collapse if theories are correct. 



 All images taken from, http://www.pbs.org/wgbh/nova/einstein/relativity/ 

 Lightman, Alan. "Relativity and the Cosmos." //Nova.// June 2005. PBS. 29 Jan 2009. http://www.pbs.org/wgbh/nova/einstein/relativity/

 Annotation: This site was chosen because it has many credible facts on the Theory of Relativity. The site hosted on PBS and NOVA further adding to the credibility of this site. Also, the author of this document is a physicist, novelist, and a professor at MIT. The jobs that he is involved in would eliminate any thought of inaccurate data. 