This book was started from a collection of simple computer experiments illustrated by striking computer graphics from author Stephen Wolfram. Here he shows in this landmark book how unexpected results force a whole new way of looking at the operation of our universe. He describes the fundamental problems in science. From the origins of apparent randomness in physical systems to the development of complexity in biology. He also covers the ultimate scope and limitations of mathematics, the possibility of a truly fundamental theory of physics, free will and determinism and intelligence in the unisverse.