James B. Hartle was educated at Princeton University and the California Institute of Technology where he completed a Ph.D. in 1964. He is currently Professor of Physics at the University of California, Santa Barbara. His scientific work is concerned with the application of Einstein's relativistic theory of gravitation (general relativity) to realistic astrophysical situations, especially cosmology. Professor Hartle has made important contributions to the understanding of gravitational waves, relativistic stars, and black holes. He is currently interested in the earliest moments of the Big Bang where the subjects of quantum mechanics, quantum gravity, and cosmology overlap. He has visited Cambridge often since 1971 and has collaborated closely with Stephen Hawking over many years, most notably on their famous "no boundary proposal" for the origin of the universe. Professor Hartle is a member of the U.S. National Academy of Sciences, a fellow of the American Academy of Arts and Sciences, and is a past director of the Institute for Theoretical Physics in Santa Barbara.