The bright star Sirius has a faint companion star, about the mass of the sun, but more like a planet in size. Such stars, called white dwarfs, are many thousands of times more dense than matter, which can be studied in terrestrial laboratories. Astrophysicists regard white dwarfs as examples of the ultimate fate of nearly all existing stars, a class of dying stars which no longer are capable of generating energy, but merely cooling slowly to invisibility. Thus the oldest white dwarfs are the remains of the first generation of stars in the solar neighborhood. The intense gravitational fields of white dwarfs severely distort the light they emit. This distortion, called gravitational redshift because the emitted light is reddened, is one of the classical proofs of Einstein's theory of relativity. It is also one of few techniques available to astronomers which allows the direct measurement of stellar masses. Dr. Oswalt will discuss the life cycle of stars, his studies of the white dwarf stars and the constraints these results place on the age of the Galaxy and Universe.