Heart of Darkness: Unraveling the Mysteries of the Invisible Universe Book

Acknowledgments ix

Preface xiii

• Cosmology Becomes Data-driven Science xiii
• Outline of the Journey We Will Take xix

Prologue: From Myth to Reality 1

• Astronomy: The Endless Frontier 1
• Charting and Modeling the Heavens 3
• Copernicus: "The Last of the Greek Cosmologists" 6
• Galileo: A New Approach to Mechanics and Cosmology 9
• The Impact of Copernicus: Kepler's Laws 13
• Isaac Newton and Gravity 15
• William Herschel Discovers the Universe 20
• Understanding the Universe Becomes a New Kind of Science 24

One: Einstein's Toolkit, and How to Use It 27

• Overconfidence among the Cognoscenti at the Dawn of the Twentieth Century 27
• Revolution in Physics: The Inception of Quantum Theory and Relativity 30
• Special Relativity 33
• General Relativity 36
• General Relativity Is Tested, Passes the Test, and Is a Sensation 41
• Cosmological Solutions to Einstein's Equations 47

Two: The Realm of the Nebulae 52

• New Instruments in a Better Climate Unveil a New World 52
• A Universe of Galaxies Is Confirmed 63
• A Cosmological Model to Fit the New Data: Enter, Georges Lemaître 66
• Physical Cosmology and the Expanding Universe 70
• Lemaître's Synthesis Model Foretells the Contribution of Dark Energy 75
• Hubble's Achievements 79
• Big Science to Attack the Big Problem 81
• The Steady State Model Universe and the Big Bang 84

Three: Let's Do Cosmology! 89

• The Big Bang: A Starting Point That Cannot Be Escaped 89
• Observational Cosmology, the Biggest Puzzle to Be Solved with the Biggest Telescope 93
• The Grand Project Was Initially Too Difficult 97

Four: Discovering the Big Bang 102

• Did Our Universe Have an Explosive Birth? 102
• What Makes the Stars Shine? 104
• Nuclear Astrophysics Moves to the Cosmos 109
• The Fireball in Which the First Chemical Elements Were Made 114
• Direct Radio Observations of the Big Bang Fireball 118
• Understanding the Big Bang 125

Five: The Origin of Structure in the Universe 130

• "In the Beginning"?Why an Explanation Is Needed 130
• Structure within the Expanding Universe 136
• The Elusive Standard Candle: Beatrice Tinsley Changes the Game 139
• Real Cosmic Structure Found and Cataloged by Fritz Zwicky 146
• Understanding the Origin of Structure Becomes Serious Science 149
• Cosmic Inflation 155
• The Seeds of Cosmic Structure Are Discovered 162
• Closing the Loop: How Do Seeds Grow to Galaxies? 168

Six: Dark Matter-or Fritz Zwicky's Greatest Invention 174

• How the Earth Was Weighed 174
• Finding the Mass of the Andromeda Galaxy 181
• Zwicky Finds Dark Matter in Clusters of Galaxies in the 1930s 184
• The Rediscovery of Dark Matter in the 1970s 187
  Rotation Curves Confirm the Case for Dark Matter 193
• More Recent Multiple Lines of Evidence for Dark Matter 197

Seven: Dark Energy—or Einstein's Greatest Blunder 202

• A Curious Situation 202
• Will Gravity Lead to a Collapse of the Solar System? 203
• Expected and Unexpected Motions of Thrown Stones and Hubble's Universe 205
• The Invention of the Cosmological Constant or Dark Energy: 1915 209
• The Revival of Dark Energy in the 1970s 215
• New Arguments and New Evidence—Dark Energy Confirmed in the 1990s 220
• Dark Energy Fills the Gap, Allowing the Flat, "Just Right" Universe 222

Eight: The Modern Paradigm and the Limits of Our Knowledge 229

• We Have Come a Long Way 229
• The Matter and Energy Content of the Universe 231
• The Global Cosmological Solution and the Cosmic Triangle 238
• In the Beginning 244
• Structure in the Universe 245
• The Supercomputer Approach 248

Nine: The Frontier: Major Mysteries That Remain 253

• Dark Matter 253
• Dark Energy 255
• Inflation 257
• Giant Black Holes 260
• Fine-Tuning 261
• Summing Up 262

Appendixes 263

Glossary 281

Bibliography 291

Index 295