Invisible Matter and the Fate of the Universe

Transcription

1 Invisible Matter and the Fate of the Universe

2 OTHER RECOMMENDED BOOKS BY BARRY PARKER CREATION The Story of the Origin and Evolution of the Universe EINSTEIN'S DREAM The Search for a Unified Theory of the Universe SEARCH FOR A SUPERTHEORY From Atoms to Superstrings

3 Invisible Matter and the Fate of the Universe Barry Parker Drawings by Lari Scaffield Springer Science+Business Media, LLC

4 Library of Congress Cataloging in Publication Data Parker, Barry R. Invisible matter and the fate of the universe / Barry Parker; drawings by Lori Scoffield. p. cm. Includes bibliographical references and index. 1. Cosmology-Popular works. 2. Dark matter (Astronomy)-Popular works. I. Title. QB982.P dc20 CIP ISBN ISBN (ebook) DOI / Springer Science+Business Media New York Originally published by Barry Parker in Softcover reprint of the hardcover 1 st edition 1989 All rights reserved No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical. photocopying, microfilming, recording, or otherwise, without written permission from the Publisher

5 Preface Contemplation of the fate of the universe, and of course the end of the world, reminds me of the story of a traveler in the Swiss Alps. After hiking high into the mountains he and his guide spent the night in a chalet. Early the next morning he was awakened by a resounding crash, followed by a deafening roar and several loud cracks. Jumping out of bed in fright he ran to his guide and yelled, "What is happening? Is the world coming to an end?" The guide calmly sat up in his bed. "No... don't worry... it's just the rays of the sun. When they touch the snow on the peak of the mountain they cause it to hurl down into the valley. Then the rays warm the glacier, causing it to crack. It's not the end of the world, it's the dawn of a new day." In the latter part of the book I will also be talking about the end of the world, and the fate of the universe. But, like the Swiss guide, I'd like to assure you that there is nothing to worry about: barring something unforeseen, no serious astronomical catastrophe will take place for millions of years. Still, the final fate of the universe is something we would like to know about, and understand. What will eventually happen to it? The key, it seems, is the amount of matter it contains. And, as you will see, part of this matter is invisible, or is at least hidden from us in some strange form. Scientists refer to it as dark matter. In an earlier book (Creation) I described the birth and evolution of the universe up to the present. I like to think of the present book as the continuation of this story. The fate of the univ

6 vi PREFACE verse, however, depends on the amount of dark matter in it, and as a result, much of the book is directed to this topic. As you read it you will find that scientists are still unable to identify this dark matter. Many challenging problems remain. But, of course, that is what science is all about. In writing a popular science book about a technical subject it is difficult to avoid all scientific terms. I have had to use a few, and have defined them as they arose. For those unfamiliar with such terms I have included a glossary at the end of the book. Another difficulty for some may be the notation I use for very large and very small numbers. To write them out in detail would be cumbersome, so I have used scientific notation. In this notation a number such as 10,000 is written 104 (the index is the number of zeros after the one). You may also be unfamiliar with the temperature scale I use, namely the Kelvin scale (K). On this scale the lowest temperature in the universe is 0 K (this is -459 F on the Fahrenheit scale). I am particularly grateful to the scientists who assisted me. Interviews were conducted, in most cases by telephone or letter, with many of the people mentioned in the book. I would like to thank them both for the interviews, and in some cases for photographs and reprints. They are: David Schramm, Jim Peebles, Jeremiah Ostriker, Halton Arp, Jan Oort, Gerhard Borner, Julius Wess, Vera Rubin, Craig Hogan, James Applegate, Virginia Trimble, Michael Turner, Geoffrey Burbidge, Richard Price, Marc Davis, Simon White, Edwin Turner, Anthony Tyson, John Bahcall, Joseph Silk, Freeman Dyson, Don Page, Randall McKee, Scott Tremaine, C. S. Frenk. The sketches, cartoons, paintings, and some of the line drawings were done by Lori Scoffield. The remaining line drawings were done by Shawn Jensen. I thank them both for an excellent job. I would also like to thank Linda Greenspan Regan, Victoria Cherney, and the staff of Plenum for their assistance in bringing the book to its final form. And finally I would like to thank my wife for her support while the book was being written. Barry Parker

7 Contents CHAPTER 1 Introduction 1 CHAPTER 2 The Expanding Universe 15 Herschel and Company 19 Dawn of a New Era 23 Discovery of the Expansion 26 Controversy 32 CHAPTER 3 The Missing Mass Mystery Unfolds 43 CHAPTER 4 Dark Matter in Galaxies? 55 Instability 58 Rubin and Ford 63 CHAPTER 5 Dark Matter in the Universe? 77 Density Tests 82 Tests of Curvature 82 vii

8 viii CONTENTS Nucleosynthesis 87 The Flatness Problem 90 Other Problems 92 CHAPTER 6 Will the Candidates Please Stand 95 The Dwarfs: Red, Brown, Black, and White 97 Hydrogen 100 Stellar Corpses 104 The Radiations 105 Exotic Particles 107 The Mimics 109 Missing Mass of the Universe 110 Opinions 111 CHAPTER 7 Black Holes 113 The Discovery 113 Primordial and Evaporating Black Holes 127 Basic Properties and Candidates 130 Black Holes as Dark Matter 132 CHAPTER 8 Neutrinos with Mass 135 The Discovery 135 Complications 140 Does the Neutrino Have Mass? 142 Massive Neutrinos as Dark Matter 145 Magnetic Monopoles and Other Exotic Particles 147 CHAPTER 9 Magnetic Monopoles 147 Magnetic Monopoles as Dark Matter 157

9 CONTENTS ix Supersymmetric Particles 158 The Axion and Other Candidates 161 CHAPTER 10 Galaxy Formation and Dark Matter 163 Survey of the Universe 165 Models of Structure Formation 168 Computer Simulations 169 A Cold Dark Matter Universe 176 Biased Galaxy Formation 178 Explosive Galaxy Formation and Cosmic Strings 180 CHAPTER 11 Gravitational Lenses and Dark Matter 183 A Closer Look at the Gravitational Lens 186 Discovery of the First Gravitational Lens 188 Lens Surveys and Dark Matter 195 CHAPTER 12 A Consensus: To Be or Not To Be 201 The Candidates 207 The Search for Exotic Particles 209 Opinions from the Experts 212 A New Revolution? 215 CHAPTER 13 Fate of the Open Universe 219 Stage 1: The Death of Stars Stage 2: Stars Lose Planets Stage 3: Galaxies Lose Stars Stage 4: Proton Decay 229 Stage 5: Hawking Evaporation The Universe at Critical Density

10 x CONTENTS CHAPTER 14 Fate of the Closed Universe 237 Approaching the Singularity 242 Bounce 244 Quantum Cosmology 245 The Many-Universe Concept 247 The Anthropic Principle 249 CHAPTER 15 The Future of Civilization and Life 253 Fate of Earth 253 The Exodus to Near Space 256 Flight to the Stars 260 Other Civilizations 264 How Long Will Civilization and Life Survive into the Future? 268 CHAPTER 16 Epilogue 273 Glossary 275 Bibliography 283 Index 291