EPIC OF EVOLUTION Other Books by Eric Chaisson Cosmic Dawn: The Origins of Matter and Life The Invisible Universe: Probing the Frontiers of Astrophysics (with G. B. Field) The Life Era: Cosmic Selection and Conscious Evolution Relatively Speaking: Black Holes, Relativity, and the Fate of the Universe Universe: An Evolutionary Approach to Astronomy Astronomy Today (with S. M. McMillan) The Hubble Wars: Astrophysics Meets Astropolitics in the Two-billion-dollar Struggle Over the Hubble Space Telescope Astronomy: A Beginner’s Guide to the Universe (with S. M. McMillan) The Thirteenth Labor: Improving Science Education (coedited with T.-C. Kim) Cosmic Evolution: The Rise of Complexity in Nature EPIC OF EVOLUTION SEVEN AGES OF THE COSMOS ERIC CHAISSON Illustrated by Lola Judith Chaisson Columbia University Press NEW YORK Columbia University Press Publishers Since 1893 New York Chichester, West Sussex Copyright © 2005 Columbia University Press All rights reserved Library of Congress Cataloging-in-Publication Data Chaisson, Eric. Epic of evolution : seven ages of the cosmos / Eric Chaisson ; illustrated by Lola Judith Chaisson. p. cm. Includes bibliographical references and index. ISBN 0–231–13560–2 (cloth : alk. paper) 1. Cosmology. 2. Life—Origin. 3. Matter—Constitution. I. Title. QB981.C414 2005 523.1—dc22 2005045452 I Columbia University Press books are printed on permanent and durable acid-free paper. Printed in the United States of America c 10 9 8 7 6 5 4 3 2 1 To our parents ∞ Contents Preface ix Prologue: Cosmological Overview 1 1. Particle Epoch: Simplicity Fleeting 47 2. Galactic Epoch: Hierarchy of Structures 79 3. Stellar Epoch: Forges for Elements 132 4. Planetary Epoch: Habitats for Life 190 5. Chemical Epoch: Matter Plus Energy 248 6. Biological Epoch: Complexity Sustained 298 7. Cultural Epoch: Intelligence to Technology 369 Epilogue: A Whole New Era 433 Further Reading 443 Glossary 445 Index 463 Preface “Everything flows and nothing stays.” —Heraclitus, a Greek philosopher of twenty-five centuries ago WHEN CONSCIOUSNESS DAWNED among the ancestors of our civilization, men and women perceived two things. They noted themselves, and they noted their environment. They wondered who they were and whence they came. They longed for an understanding of the starry points of light in the nighttime sky, of the surrounding plants and ani- mals, of the air, land, and sea. They contemplated their origin and their destiny. Thousands of years ago, all these basic queries were treated as sec- ondary, for the primary concern seemed well in hand: Earth was pre- sumed to be the stable hub of the Universe. After all, the Sun, Moon, and stars all appear to revolve around our planet. It was natural to con- clude, not knowing otherwise, that home and selves were special. This centrality led to a feeling of security or at least contentment—a belief that the origin, maintenance, and fate of the Universe were governed by something more than natural, something supernatural. The ancients thought deeply and well, but not much more. Logic was paramount; empiricism less so. Their efforts nonetheless produced such notable endeavors as myth, religion, and philosophy. Eventually, yet only a few hundred years ago, the idea of Earth’s cen- trality and the reliance on supernatural beings were shattered. During the Renaissance, humans began to inquire more critically about them- x PREFACE selves and the Universe. They realized that thinking about Nature was no longer sufficient. Looking at it was also necessary. Experiments be- came a central part of the process of inquiry. To be effective, ideas had to be tested experimentally, either to refine them if data favored them or to reject them if they did not. The “scientific method” was born— probably the most powerful technique ever conceived for the advance- ment of factual information. Modern science had arrived. Today, all natural scientists throughout the world employ the scien- tific method. Normally it works like this: First, gather some data by ob- serving an object or event, then propose an idea to explain the data, and finally test the idea by experimenting with Nature. Those ideas that pass the tests are selected, accumulated, and conveyed, while those that don’t are discarded—a little like the evolutionary events described in this book. In that way, by means of a selective editing or pruning of ideas, scientists discriminate between sense and nonsense. We gain an ever-better ap- proximation of reality. Not that science claims to reveal the truth— whatever that is—just to gain an increasingly accurate model of Nature. Despite an emphasis on objectivity, some subjectivity does affect the modern scientific enterprise, for this is work done by human beings with strong emotions and personal values. Yet, with the test of time and repeated observations, objectivity eventually emerges and then domi- nates, enabling us to reach conclusions free of the biased viewpoint of any one scientist, institution, or culture. As a rational investigative ap- proach used to formulate descriptions of natural phenomena, the sci- entific method is designed to yield a reasonably objective consensus on the nature, contents, and workings of the Universe. People today still query along the same lines as did the ancients. We ask the same fundamental questions: Who are we? Where did we come from? What is the origin of all things? But our attempts to answer them are now aided by the intricate tools of modern technology: astronomi- cal telescopes to improve our vision of the macroscopic realm of stars and galaxies; biological microscopes to display up close the minute world of cells and molecules; particle accelerators to probe the sub- atomic domain of nuclei and quarks; robotic spacecraft to gather facts unavailable from our vantage point on Earth; powerful computers to keep pace with the prodigious flow of new data, tentative ideas, and ex- perimental tests. We live in an age of technology—a time of rapid intellectual ad- vancement unprecedented in history. And even though technology PREFACE xi threatens to overwhelm us—perhaps even replace us—that same tech- nology now provides us with a remarkable, yet still growing, under- standing of ourselves and our richly endowed Universe. Of all the scientific achievements since Renaissance times, one discov- ery stands out most boldly: Our planet seems neither central nor spe- cial. Use of the scientific method has demonstrated that as living crea- tures, we inhabit no unique place in the cosmos. Research, especially within the past few decades, strongly implies that we live on an ordinary rock called Earth, one planet orbiting an average star called the Sun, one star in the suburbs of a much larger swarm of stars called the Milky Way, one galaxy among billions of others spread throughout an observable abyss called the Universe. Now, at the beginning of a new millennium, modern science is help- ing us construct a truly big picture. We are coming to appreciate how all objects—from quark to quasar, from microbe to mind—are inter- related. We are attempting to decipher the scenario of cosmic evolution: a grand synthesis of many varied changes in the assembly and compo- sition of radiation, matter, and life throughout the history of the Uni- verse. These are the changes, operating across almost incomprehensible domains of space and nearly inconceivable durations of time, that have given rise to our galaxy, our star, our planet, and ourselves. To be sure, change is ubiquitous in Nature. Some of that change is subtle, such as when our Sun shines daily or Earth’s continents drift slowly. Other change is more dramatic, such as when massive stars ex- plode catastrophically as supernovae or when landmasses fault suddenly as quakes and volcanoes. Regardless of whether Nature is examined macroscopically with a telescope, microscopically with an accelerator, or mesoscopically with our own eyes, we see change. Thus, we give this process of universal change a more elegant name—cosmic evolution, which includes all aspects of evolution: particulate, galactic, stellar, planetary, chemical, biological, and cultural. Emerging now is a unified worldview of the cosmos, including our- selves as sentient beings, based upon the time-honored concept of change. Change—to make different the form, nature, and content of something—has been the hallmark in the origin, evolution, and fate of all things, animate or inanimate. From galaxies to snowflakes, from stars and planets to life itself, we are beginning to identify an underly- ing pattern penetrating the fabric of all the natural sciences—a sweep- xii PREFACE ingly encompassing view along the “arrow of time” of the formation, structure, and function of all objects in our multitudinous Universe. ...a sweepingly encompassing view along the “arrow of time”... Heraclitus of old Greece had it correct: Everything flows; nothing is permanent except change. It’s perhaps the best observation anyone ever made, minus the devilish details. Today, some twenty-five centuries later, scientific researchers are steadily discovering many of those details—and the results are both insightful and unifying, even awesome. We now have a reasonably good understanding not only of how countless stars were born and have died to create the matter composing our world but also how life has come to exist as a natural consequence of the evolution of matter. We can reliably trace a thread of knowledge linking the evolu- tion of primal energy into elementary particles, the evolution of those particles into