Table Of Content

Also by Neil deGrasse Tyson The Sky Is Not the Limit: Adventures of an Urban Astrophysicist Cosmic Horizons: Astronomy at the Cutting Edge (with Steven Soter, eds.) One Universe: At Home in the Cosmos (with Charles Liu and Robert Irion) Universe Down to Earth Just Visiting This Planet Merlin’s Tour of the Universe Also by Donald Goldsmith Chaos to Cosmos: A Space Odyssey (with Laura Danly and Leonard David) Connecting with the Cosmos: Nine Ways to Experience the Wonder of the Universe The Search for Life in the Universe (with Tobias Owen; 3rd ed.) The Runaway Universe: The Race to Find the Future of the Cosmos The Ultimate Planets Book Worlds Unnumbered: The Search for Extrasolar Planets The Ultimate Einstein (with Robert Libbon) Einstein’s Greatest Blunder? The Cosmological Constant and Other Fudge Factors in the Physics of the Universe Fourteen Billion Years of Cosmic Evolution Neil deGrasse Tyson and Donald Goldsmith W. W. NORTON & COMPANY NEW YORK • LONDON To all those who look up, And to all those who do not yet know why they should Contents Acknowledgments A Meditation on the Origins of Science and the Science of Origins PREFACE The Greatest Story Ever Told OVERTURE Part I: The Origin of the Universe In the Beginning CHAPTER 1 Antimatter Matters CHAPTER 2 Let There Be Light CHAPTER 3 Let There Be Dark CHAPTER 4 Let There Be More Dark CHAPTER 5 One Universe or Many? CHAPTER 6 Part II: The Origin of Galaxies and Cosmic Structure Discovering Galaxies CHAPTER 7 The Origin of Structure CHAPTER 8 Part III: The Origin of Stars Dust to Dust CHAPTER 9 The Elemental Zoo CHAPTER 10 Part IV: The Origin of Planets When Worlds Were Young CHAPTER 11 Between the Planets CHAPTER 12 Worlds Unnumbered: Planets Beyond the Solar System CHAPTER 13 Part V: The Origin of Life Life in the Universe CHAPTER 14 The Origin of Life on Earth CHAPTER 15 Searching for Life in the Solar System CHAPTER 16 Searching for Life in the Milky Way Galaxy CHAPTER 17 The Search for Ourselves in the Cosmos CODA Glossary of Selected Terms Further Reading Image Credits Index Photo Insert Acknowledgments For reading and rereading the manuscript, ensuring that we mean what we say and say what we mean, we are indebted to Robert Lupton of Princeton University. His tandem expertise in astrophysics and the English language allowed the book to reach several notches higher than we had otherwise imagined for it. We are also grateful to Sean Carroll at Chicago’s Fermi Institute, Tobias Owen of the University of Hawaii, Steven Soter of the American Museum of Natural History, Larry Squire of UC San Diego, Michael Strauss of Princeton University, and PBS NOVA producer Tom Levenson for key suggestions that improved several parts of the book. For expressing confidence in the project from the beginning, we thank Betsy Lerner of the Gernert Agency, who saw our manuscript not only as a book but also as an expression of deep interest in the cosmos, deserving the broadest possible audience with whom to share the love. Major portions of Part II and scattered portions of Parts I and III first appeared as essays in Natural History magazine by NDT. For this, he is grateful to Peter Brown, the magazine’s editor in chief, and especially to Avis Lang, their senior editor, who continues to work heroically as a learned literary shepherd to NDT’s writing efforts. The authors further recognize support from the Sloan Foundation in the writing and preparation of this book. We continue to admire their legacy of support for projects such as this. Neil deGrasse Tyson, New York City Donald Goldsmith, Berkeley, California June 2004 PREFACE A Meditation on the Origins of Science and the Science of Origins A new synthesis of scientific knowledge has emerged and continues to flourish. In recent years, the answers to questions about our cosmic origins have not come solely from the domain of astrophysics. Working under the umbrella of emergent fields with names such as astrochemistry, astrobiology, and astro-particle physics, astrophysicists have recognized that they can benefit greatly from the collaborative infusion of other sciences. To invoke multiple branches of science when answering the question, Where did we come from? empowers investigators with a previously unimagined breadth and depth of insight into how the universe works. In Origins: Fourteen Billion Years of Cosmic Evolution, we introduce the reader to this new synthesis of knowledge, which allows us to address not only the origin of the universe but also the origin of the largest structures that matter has formed, the origin of the stars that light the cosmos, the origin of planets that offer the likeliest sites for life, and the origin of life itself on one or more of those planets. Humans remain fascinated with the topic of origins for many reasons, both logical and emotional. We can hardly comprehend the essence of anything without knowing where it came from. And of all the stories that we hear, those that recount our own origins engender the deepest resonance within us. Self-centeredness bred into our bones by our evolution and experience on Earth has led us naturally to focus on local events and phenomena in the retelling of most origin stories. However, every advance in our knowledge of the cosmos has revealed that we live on a cosmic speck of dust, orbiting a mediocre star in the far suburbs of a common sort of galaxy, among a hundred billion galaxies in the universe. The news of our cosmic unimportance triggers impressive defense mechanisms in the human psyche. Many of us unwittingly resemble the man in the cartoon who gazes at the starry heavens and remarks to his companion, “When I look at all those stars, I’m struck by how insignificant they are.” Throughout history, different cultures have produced creation myths that explain our origins as the result of cosmic forces shaping our destiny. These histories have helped us to ward off feelings of insignificance. Although origin stories typically begin with the big picture, they get down to Earth with impressive speed, zipping past the creation of the universe, of all its contents, and of life on Earth, to arrive at long explanations of myriad details of human history and its social conflicts, as if we somehow formed the center of creation. Almost all the disparate answers to the quest of origins accept as their underlying premise that the cosmos behaves in accordance with general rules, which reveal themselves, at least in principle, to our careful examination of the world around us. Ancient Greek philosophers raised this premise to exalted heights, insisting that we humans possess the power to perceive how nature operates, as well as the underlying reality beneath what we observe: the fundamental truths that govern all else. Quite