The conservation of energy, the second law of thermodynamics, the theory of relativity, quantum mechanicstogether, these concepts form the foundation upon which modern physics was built. But the influence of these four landmark ideas has extended far beyond hard science. There is no aspect of twentieth-century cultureincluding the arts, social sciences, philosophy, and politicsthat has not been profoundly influenced by them. In Great Ideas in Physics, Alan Lightman clearly explains the physics behind each of the four great ideas and deftly untangles for lay readers such knotty concepts as entropy, the relativity of time, and the Heisenberg uncertainty principle. Throughout the book he uses excerpts from the writings of scientific luminaries such as Newton, Kelvin, Einstein, and de Broglie to help place each in its proper historical perspective. And with the help of expertly annotated passages from the works of dozens of writers, philosophers, artists, and social theorists, Lightman explores the two-way influences of these landmark scientific concepts on our entire human culture and the world of ideas.