On December 26, 1898, Marie Curie announced the discovery of radium and observed that "radioactivity seems to be an atomic property." A mere 47 years later, "Little Boy" exploded over Hiroshima. Before the Fallout is the epic story of the intervening half century, during which an exhilarating quest to unravel the secrets of the material world revealed how to destroy it, and an open, international, scientific adventure transmuted overnight into a wartime sprint for the bomb. Weaving together history, science, and biography, Diana Preston chronicles a human chain reaction of scientists and leaders whose discoveries and decisions forever changed our lives. The early decades of the 20th century brought Einstein's relativity theory, Rutherford's discovery of the atomic nucleus, and Heisenberg's quantum mechanics, and scientists of many nations worked together to tease out the secrets of the atom. Only 12 years before Hiroshima, one leading physicist dismissed the idea of harnessing energy from atoms as "moonshine." Then, on the eve of World War II, the power of atomic fission was revealed, alliances were broken, friendships sundered, and science co-opted by world events. Preston interviewed the surviving scientists, and she offers new insight into the fateful wartime meeting between Heisenberg and Bohr, along with a fascinating conclusion examining what might have happened had any number of events occurred differently. She also provides a rare portrait of Hiroshima before the blast. As Hiroshima's 60th anniversary approaches, Before the Fallout compels us to consider the threats and moral dilemmas we face in our still dangerous world. Describes the history of discoveries that led up to the dropping of the atomic bomb in 1945.