Generations have grown up knowing that the equation E=mc2 changed the shape of our world, but never understanding what it actually means, why it was so significant, and how it informs our daily lives today—governing, as it does, everything from the atomic bomb to a television's cathode ray tube to the carbon dating of prehistoric paintings. In this book, David Bodanis writes the "biography" of one of the greatest scientific discoveries in history—that the realms of energy and matter are inescapably linked—and, through his skill as a writer and teacher, he turns a seemingly impenetrable theory into a dramatic human achievement and an uncommonly good story.