math+formulas


 * The first person to apply Einstein's general theory was the German astrophysicist **Karl Schwarzschild**. It was 1916, and the First World War was still raging. Just a few days after reading Einstein's newly published theory while stationed at the Russian front, Schwarzschild began to figure out its consequences for the gravitational fields of stars.
 * In three-dimensional, time-dependent spacetimes, the lack of symmetry results in yet more variables. Just for the gravitational field itself, there are at least 16 variables in the standard formulation (developed for computation by Arrow itt, Deser and Misner in 1962). These variables depend on further coordinates, three for space and one for time, so there are many, many more terms in the equations.
 * This elegant symbolic formulation of Einstein's general theory of relativity cannot be used for actual calculations, but it clearly shows the principle that "matter tells spacetime how to curve, and curved space tells matter how to move"(John Wheeler, Princeton University and the University of Texas at Austin) . The left side of the equation contains all the information about how space is curved, and the right side contains all the information about the location and motion of the matter. General relativity is beautiful and simple (to a physicist), but mathemat ically it's very complicated and subtle.