An accessible narrative history of science, dealing with the most important equation in our lives. Everyone knows that Einstein's equation is important but they don't usually know why. There are already numerous books that try to describe what the equation means but for most readers they add up to a mass of odd diagrams that are utterly mystifying. This book takes a fresh approach and will concentrate not on the biography of Einstein but on the biography of the equation itself. David Bodanis looks at the ancestors of the equation, the three elements - e, m and c - before they end up together in Einstein's equation in Berne in 1905. From there he follows the course of the equation through the 20th Century focusing on the people who developed Einstein's work and its consequences. Without the equation for instance there would have been no atomic bomb, no lasers, no Internet and no science of black holes.