XI ACKNOWLEDGMENTS xiii INTRODUCTION XV CHAPTER 1: THE HISTORICAL AND PHILOSOPHICAL PERSPECTIVES 1 The Magical Vision of the Nonhuman 1 Ancient Philosophy 2 Medieval Philosophy 6 The Renaissance 8 The Birth of Modern Science 10 First Attempts at Contact 16 Cosmism 17 From Enthusiasm to Disenchantment 18 CHAPTER 2: THE RELIGIOUS PERSPECTIVE 23 Is Extraterrestrial Life a Threat to Religion? 23 A Finite Universe and an Infinite God 25 Hinduism, Buddhism, and Other Oriental Religions 26 Judaism 27 Islam 28 Christianity 29 The Problem of Original Sin 30 The Problem of Redemption 34 Biocosmic Theology 36 Vll Contents CHAPTER 3: THE ASTROBIOLOGICAL PERSPECTIVE 41 A New Science: Astrobiology 41 Times of the Universe 43 The Anthropic Principle 47 Chemical Evolution 50 The Formation of the Solar System 51 The Formation of Extrasolar Planets 57 The Birth of Life on Earth 64 Panspermia 73 Evolution and Creationism 76 Toward a Great Complexity 81 Catastrophes and Mass Extinctions 86 Conditions Needed for the Development of Life 96 Life on Mars 107 Life in the Solar System 117 The Search for Life Outside the Solar System 123 CHAPTER 4: THE SEARCH FOR EXTRATERRESTRIAL INTELLIGENCE 129 Intelligence and Consciousness 129 Consciousness 133 The Development of Intelligence on Earth 137 From Intelligence to Technology 147 Evolution Beyond Humans 154 The Expansion of Intelligent Life 156 The Search for Intelligent Signals 164 The Pdo Scale 176 The Problem of the Answer 177 The San Marino Scale 180 Which Message? 182 Extraterrestrials, How? 187