Book excerpt: 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.