Quantum mechanics is one of the glories of our age. The theory lies at the heart of modern society. Quantum mechanics is one of our most valuable forecasters?a "great predictor.? It has immeasurably altered our conception of the natural world. Its philosophical implications are earthshaking. But quantum mechanics steadfastly refuses to speak of many things, it deals in probabilities rather than giving explicit descriptions. It never explains. Einstein, one of its creators, considered the theory incomplete. Even now, many years after the creation of quantum mechanics, physicists continue to argue about it. Astrophysicist George Greenstein has been both fascinated and confused by quantum mechanics for his entire career. In this book, he describes, engagingly and accessibly, his efforts to understand the enigma that is quantum mechanics.