Machine generated contents note: Preface ix -- 1 The Foundations for a New Kind of Science I -- 2 The Crucial Experiment 23 -- 3 The World of Simple Programs 51 -- 4 Systems Based on Numbers 115 -- 5 Two Dimensions and Beyond 169 -- 6 Starting from Randomness 223 -- 7 Mechanisms in Programs and Nature 297 -- 8 Implications for Everyday Systems 363 -- 9 Fundamental Physics 433 -- 10 Processes of Perception and Analysis 547 -- 11 The Notion of Computation 637 -- 12 The Principle of Computational Equivalence 715 -- Notes 849 -- Index 1201.