Black Holes

*Taught Online for Summer 2021*  White dwarfs, neutron stars and black holes, the so-called compact objects, are among the most remarkable object in the universe. Their most distinctive feature which ultimately is the one responsible for their amazing properties is their prodigiously high density.  All compact objects are the product of the final stages of stellar evolution. White dwarfs have masses comparable to that of the Sun but with the size of the Earth, they come from "smallish" stars that run out of nuclear fuel and settle down to a quiet life of slowly fading away.

Neutron stars and black holes come from much more massive stars that end their lives in a spectacular explosion known as a supernova.  In a neutron star the mass of the Sun is concentrated in the size of a city. The density is so high that even electron and proton get squished together to form neutrons (hence the name). In a black hole the density is so high that nothing can counter gravity and eventually the collapsing star folds the space-time around itself and disappears inside a "surface of no return”- the event horizon.

In this course we will address the progenitor problem--which stars become which compact object. We will examine the properties of each type of compact object and address the issue of their remarkable structure. For the case of black holes, we will see that they are completely geometrical, and in some real sense, the most perfect objects in the universe.