Until the late 1800s, scientists saw the atom much as the ancient Greeks had: as the smallest possible division of matter. Then, J. J. Thomson discovered the electron, establishing the existence of subatomic particles and launching an entirely new field of science, called particle physics. Through primary sources and beautiful photographs, this book brings the science of particle physics to stunning focus. The text discusses the state of science, particularly chemistry, before Thomson's experiments, the discoveries that helped guide Thomson's work, and the scientists who had a hand in the development of particle physics. Readers will also discover the key ideas behind particle physics and the role of technologies such as colliders in our lives today.