Robert M. Walker Distinguished Lecture Series Public Lecture
A black hole is an object which is so compact, and whose gravitational pull is so strong, that nothing--not even light--can escape from its interior. The concept of a black hole is very bizarre and one feels that something in physics ought to prevent the formation of such objects. But this is not the case. On the contrary, the universe contains countless numbers of black holes; some that weigh only about ten times the mass of the Sun and others as much as a billion times more. Even though light cannot escape from inside a black hole, gas flowing into the hole does emit very intense radio waves, light, X-rays and gamma rays. Astronomers study such radiation on a daily basis with telescopes based on the ground and those launched into space. This talk will describe the kinds of black holes that have been discovered, their observational manifestations, and what they teach us about the formation of such compact objects in nature.