For nearly sixty years the menace of nuclear war has hung over humanity, while at the same time the promise of nuclear energy has enticed us. In Megawatts and Megatons, two of the world’s most eminent physicists—French Nobel Prize laureate Georges Charpak and American Enrico Fermi Award–winner Richard L. Garwin—assess with consummate authority the benefits of nuclear energy and the dangers of nuclear weaponry. Garwin and Charpak begin by elucidating the discoveries that have allowed us to manipulate nuclear energy with increasing ease. They clearly and concisely explain complex principles of fission and fusion pertaining to nuclear weaponry and the generation of nuclear electric power. They also make a strong and eloquent argument in favor of arms control. More than ten thousand nuclear weapons in the former Soviet Union, together with a similar number in the United States, have the capacity to destroy the world many times over. The “nuclear club” of nations is growing, with India and Pakistan its latest members and Iran, Iraq, and North Korea striving for admission. Even the possibility of a single weapon in the hands of a terrorist group—or a lone terrorist—poses a threat that we cannot ignore. Meanwhile, nuclear power already provides one-sixth of all electrical energy in the world—France, for instance, derives 80% of its electricity from reactors— but nuclear power has met with great resistance in the United States, where the specter of the Three Mile Island breakdown still looms in the public’s consciousness. Garwin and Charpak take a temperate, rational tone in evaluating the benefits of nuclear energy. They show how it can provide an assured, economically feasible, and environmentally responsible supply of energy in a way that avoids the hazards of weapons proliferation. Cogently written, passionately and carefully ar-gued—and featuring explanatory technical drawings as well as illustrations by the world-famous French cartoonist Sempé—Megawatts and Megatons is a thoughtful and important primer on two of the central issues of our time.