The Development of Relativity相对论发展.ppt

All observers can agree on the absolute interval. World line – line of person or object during existence. Curved space-time Imagine a spinning vinyl record. The outer edge covers more distance per revolution than the center. The velocity of the outer edge is greater than the center, therefore it will shrink more than the center. The record becomes dome shaped as it rotates very fast. Swirling galaxies, etc. must curve space. Geometry for curved space Euclidean Geometry only held for flat space. Math for curved space is differential geometry (tensor calculus), developed by George Friedrich Riemann in the 1850s. Einstein did not have these math skills, so he asked his former classmate Grossman for help. Math of curved space is applied to universe Einstein and Grossmann reworked Minkowski’s four dimensional, linear space-time into curved space-time. The amount of mass and energy determines curvature at that location. True nature of gravity The gravitational field does not pull objects, it simply curves space-time as determined by the amount of mass and energy. Objects moving towards the earth are simply following the shortest space-time path as determined by the curvature of space. Newton had it backwards: Objects in free-fall are not being acted on by a force, which is why we feel no force in free-fall. Not following the natural space-time path requires a force and is an acceleration. You are undergoing acceleration by simply standing on the earth because the earth is holding you back from the path. General Relativity’s Final Form Einstein completed the final form of this theory in 1915. It explained the wobble in Mercury’s orbit. The 1919 solar eclipse also supported the theory. In it’s simplest form, Guv = 8πTuv  The left side defines the universe’s shape. The right side tells matter-energy (all that the universe contains) how to move. Strengths of Relativity It explains the constant speed of light. It preserves Newton’s equations for everyday