General Theory of Relativity (a gravity theory): Ingredients: The Principle of Equivalence: acceleration ~ gravity Riemann's Curved Geometry: acceleration ~ curved space-time ( ' ~ ' means 'is equivalent to'.) This implies: gravity ~ curved space-time (Einstein's Field Eqns.) This is important when objects are massive, like sun or black hole. Supercedes Newton's Law in these cases. Three experimental-observational proofs of General Relativity: 1. Perihelion precession of Mercury's orbit. (Slow rotation of ellipse. 2. Light bends near the sun. Time slows in a strong gravity field. (Ex. Gravitational redshift, and clocks flown in planes vs those on ground.)

The General Theory of Relativity (GTR) is based on: The Principle of Equivalence: acceleration ~ gravity Conceived by Ernst Mach 1838-1902

George Riemann 1826-1866 Riemann's Curved Geometry was another ingredient: acceleration ~ curved space-time

The essential idea of Einstein’s GTR gravity ~ curved space-time (Einstein's Field Eqns. ) This is important when objects are massive, like sun or black hole. Supercedes Newton's Law in these cases.

Black hole—HELP! We need Einstein!

Three experimental-observational proofs of General Relativity: Perihelion precession of Mercury's orbit (slow rotation of ellipse 16 degrees/10,000 yrs).

Three experimental-observational proofs of General Relativity: 2. Light bends near the sun.

Arthur Eddington went to South Africa during a total eclipse of the sun To test the bending of light by the sun’s gravity.

Three experimental-observational proofs of General Relativity: 3. Time slows in gravity