Although modern physics surrounds us, and newspapers constantly refer to its concepts, most nonscientists find the subject extremely intimidating. Complicated mathematics or gross oversimplifications written by laypersons obscure most attempts to explain physics to general readers. Now, at long last, we have a comprehensive--and comprehensible--account of particles, fields, and cosmology, written by a working physicist who does not burden the reader with the weight of ponderous scientific notation. Exploring how physicists think about problems, Robert K. Adair considers the assumptions they make in order to simplify impossibly complex relationships between objects, how they determine on what scale to treat the problem, how they make measurements, and the interplay between theory and experiment. Adair gently guides the reader through the ideas of particles, fields, relativity, and quantum mechanics. He explains the great discoveries of this century--which have caused a revolution in how we view the universe--in simple, logical terms, comprehensible with a knowledge of high school algebra. Performing the difficult task of predigesting complex concepts, Adair gives nonscientists access to what often appears to be an arcane discipline, and captures the the joy of discovery which lies at the heart of research.