AST201H1 Lecture Notes - Lecture 5: Gravitational Lens, Strong Gravity, Equivalence Principle

• School: UTSG
• Department: Astronomy & Astrophysics
• Course: AST201H1
• Professor: Bryan Gaensler, C. Barth Netterfield, Ilana MacDonald

Document Summary

Equivalence principle: no experiment can distinguish a difference between gravity pulling things back to the surface of earth and acceleration. We feel weight on us because either we are feeling gravity, or the earth is accelerating through space. Coasting in a rocket means the person inside the rocket sees the laser angled down because they are moving up. Accelerating past the person outside, but by the time the laser takes to get from left to right, the rocket has accelerated and thus the light looks curve. Gets left behind by more distance and that is why it looks like it is bending. If there is no way to tell the difference between acceleration and gravity, then gravity must make the light bend to make the theory true. Light must curve in a gravitational field (though by a very small amount) since acceleration bends light.