Richard P. Feynman was arguably the greatest American-born theoretical physicist of the twentieth century. A teacher, showman, bongo drummer, and iconoclast of the first rank, he distained authority and despised ceremony, yet was a scientific magician capable of transcendental leaps of the imagination. The Beat of a Different Drum is the definitive account of Feynman's life and work. It covers his childhood, his three marriages, and his extraordinary range of interests. But most importantly, it deals in great detail with his scientific work - from his research on the atomic bomb, via his famous path integral formulation of quantum mechanics, to the quantum theory of gravitation, partons, quark jets, and the limits of computation. Jagdish Mehra personally knew Richard Feynman for thirty years. Feynman invited Mehra to spend three weeks of interviews with him shortly before his death on 15 February 1988, and encouraged him to write this book. What has emerged is a truly authoratitive account of the life and achievements of one of the greatest men of our century.