AST201H1 Lecture Notes - Gravitational Lens

• School: UTSG
• Department: Astronomy & Astrophysics
• Course: AST201H1
• Professor: Michael Reid

Document Summary

Unique prediction of general relativity (not found in newton"s theory) that light will bend as it passes large object. Gravitational lensing= the bending of light by large objects/bodies. Speed needed to escape the gravitational pull of a planet/body. Must reach this speed to get out of orbital path. Certain speed needed to reach a circular orbit. If you compressed the earth the escape speed would actually go up because the closer you are to an object"s centre of gravity the larger the gravitational pull is. Once the escape speed reaches the speed of light nothing can escape. This is what we call a black hole. You"ve have bent space-time as much as you can possibly bend it. Maybe even torn space-time but we don"t know. From the perspective of someone outside the black hole it would look as if time for you had stopped.