Is the universe actually a giant quantum computer? According to Seth Lloyd, the answer is yes. All interactions between particles in the universe, Lloyd explains, convey not only energy but also information-in other words, particles not only collide, they compute. What is the entire universe computing, ultimately? Its own dynamical evolution, he says. As the computation proceeds, reality unfolds. Programming the Universe, a wonderfully accessible book, presents an original and compelling vision of reality, revealing our world in an entirely new light.