AST201H1 Lecture Notes - Lecture 3: Escape Velocity, Event Horizon, Equivalence Principle

• School: UTSG
• Department: Astronomy & Astrophysics
• Course: AST201H1
• Professor: Bryan Gaensler

Document Summary

The equivalence principle states that no experiment can distinguish a gravitational force from a corresponding acceleration of the whole reference frame. Shining light while not moving at all = light moves horizontally in straight line. Shining light while moving at constant velocity = light moves in straight line downwards. Shining light while accelerating at faster and faster speed = light curves downwards (not in straight line) Equivalence principle says that gravity and acceleration are indistinguishable. Curvature occurs on spaceship that is accelerating and on earth without movement (effect of gravity) So if acceleration bends light, gravity must bend light too. Light beams bend in gravity but because it travels so fast and the earth is slower, the different is small. Anything true for a is true for g. General relativity does away with gravity and replaces it with curved spacetime. Gravity is not a force but an illusion. Objects follow the straightest possible path through spacetime.