Where Is Everybody

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Stephen Webb



Copernicus Books in association with

Praxis Publishing Ltd.

An Imprint of Springer-Verlag

© Praxis Publishing Ltd, 2002.

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the publisher.

Published in the United States by Copernicus Books, an imprint of Springer-Verlag New York, Inc.

A member of BertelsmannSpringer Science+Business Media GmbH

Copernicus Books 37 East 7th Street New York, NY 10003 www.copernicusbooks.com

Library of Congress Cataloging-in-Publication Data Webb, Stephen.

If the universe is teeming with aliens . . . where is everybody? : fifty solutions to the Fermi paradox and the problem of extraterrestrial life / Stephen Webb. p. cm.

Includes bibliographical references and index. ISBN 0-387-95501-1 (acid-free paper)

1. Fermi paradox. 2. Life on other planets. 3. Fermi, Enrico, 1901-1945. I. Title. QB54.W384 2002 576.8'39—dc21 2002073910

Manufactured in the United States of America. Printed on acid-free paper.


ISBN 0-387-95501-1

SPIN 10879967

To Heike

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Preface ix

Figure Credits xi

Chapter 1 Where Is Everybody? 1

Chapter 2 Of Fermi and Paradox 7

Enrico Fermi 8

Paradox 12

The Fermi Paradox 17

Chapter 3 They Are Here 27

solution 1 They Are Here and They Call Themselves Hungarians 28

solution 2 They Are Here and Are Meddling in Human Affairs 29

solution 3 They Were Here and Left Evidence of Their Presence 33

solution 4 They Exist and They Are Us — We Are All Aliens! 44

solution 5 The Zoo Scenario 46

solution 6 The Interdict Scenario 49

solution 7 The Planetarium Hypothesis 51

solution 8 God Exists 55

Chapter 4 They Exist But Have Not Yet Communicated 61

solution 9 The Stars Are Far Away 62

solution 10 They Have Not Had Time to Reach Us 72

solution 11 A Percolation Theory Approach 74

solution 12 Bracewell-von Neumann Probes 79

solution 13 We Are Solar Chauvinists 84

solution 14 They Stay at Home ... 85

solution 15 ... and Surf the Net 86 solution 16 They Are Signaling But We Do Not Know How to Listen 88 solution 17 They Are Signaling But We Do Not Know at Which Frequency to Listen 94

solution 18 Our Search Strategy Is Wrong 102

solution 19 The Signal Is Already There in the Data 105

solution 20 We Have Not Listened Long Enough 106

solution 21 Everyone Is Listening, No One Is Transmitting 108

solution 22 Berserkers 111

solution 23 They Have No Desire to Communicate 113

solution 24 They Develop a Different Mathematics 116

solution 25 They Are Calling But We Do Not Recognize the Signal 118

solution 26 They Are Somewhere But the Universe Is Stranger

Than We Imagine 121

solution 27 A Choice of Catastrophes 122

solution 28 They Hit the Singularity 134

solution 29 Cloudy Skies Are Common 137

solution 30 Infinitely Many etcs Exist

But Only One Within Our Particle Horizon: Us 138

Chapter 5 They Do Not Exist 141

solution 31 The Universe Is Here for Us 143

solution 32 Life Can Have Emerged Only Recently 147

solution 33 Planetary Systems Are Rare 150

solution 34 We Are the First 153

solution 35 Rocky Planets Are Rare 156

solution 36 Continuously Habitable Zones Are Narrow 158

solution 37 Jupiters Are Rare 160

solution 38 Earth Has an Optimal "Pump of Evolution" 164

solution 39 The Galaxy Is a Dangerous Place 166

solution 40 A Planetary System Is a Dangerous Place 172

solution 41 Earth's System of Plate Tectonics Is Unique 180

solution 42 The Moon Is Unique 184

solution 43 Life's Genesis Is Rare 189

solution 44 The Prokaryote-Eukaryote Transition Is Rare 206

solution 45 Toolmaking Species Are Rare 211

solution 46 Technological Progress Is Not Inevitable 215

solution 47 Intelligence at the Human Level Is Rare 217

solution 48 Language Is Unique to Humans 223

solution 49 Science Is Not Inevitable 231

Chapter 6 Conclusion 233

solution 50 The Fermi Paradox Resolved . . . 234

Chapter 7 Notes and Further Reading 241

Chapter 8 References 275

Index 283


This book is about the Fermi paradox — the contradiction between the apparent absence of aliens, and the common expectation that we should see evidence of their existence. I was fascinated by the paradox when I first met it some 17 years ago, and it fascinates me still. Over those years, many authors (too many to mention here, though their names appear in the reference list at the back of this book) have enthralled me with their writing about the paradox. Their influence upon this work will be clear. I have also discussed the paradox with many friends and colleagues; although they are too numerous to mention individually, I am indebted to them all.

Several people have contributed directly to the writing of this book, and I would like to take this chance to thank them. Clive Horwood of Praxis Publishing, John Watson of Springer-Verlag and Paul Farrell of Copernicus Books have been very supportive of the project; the book would not have been completed had it not been for their advice and encouragement. (I would also like to thank John for sharing his favored resolution of the paradox over an enjoyable working lunch.) Stuart Clark provided many useful comments on an early draft of the manuscript; Bob Marriott and Timothy Yohn caught several errors and solecisms in a later draft (Bob also sent me a list of 101 resolutions of the paradox — 75 of which I agree with); and I am extremely grateful to Steve Gillett for putting me right on many scientific points. (I am, of course, responsible for those errors that remain.) Mareike Paessler was an exceptionally observant and helpful Production Editor. Her painstaking work with Assistant Editor Anna Painter improved the text enormously. Several authors and organizations kindly gave permission to reproduce figures; I am particularly grateful to thank Lora Gordon, Geoffrey Landis, Ian Wall, Susan Lendroth, Reinhard Rachel, Heather Lindsay and Merrideth Miller for help in obtaining suitable figures. Paul Bell gently corrected my misidentification of Feynman in Figure 28, and shared some interesting ideas on the paradox. I would like to thank David Glasper for sharing his recollections of a childhood incident that affected us both. Finally, of course, I would like to thank my family — Heike, Ron, Ronnie, Peter, Jackie, Emily and Abigail — for their patience. I spent time writing that I should instead have shared with them.

Stephen Webb Milton Keynes, July 2002

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I would like to acknowledge the following sources and copyright holders for granting permission to use their images.

Figures 1, 6, 7, 8, 10 and 28 are courtesy of the American Institute of Physics Emilio Segré Visual Archives. Figure 5 is © The New Yorker Collection 1950 Alan Dunn from cartoonbank.com. All Rights Reserved. Both Figures 9 and 29 are seti League photographs, used by permission. Figures 13, 15-19, 21, 22, 44-46, 48-52, 57-60 and 70 are courtesy of nasa. Figure 14 is courtesy of the Astronomical Society of the Pacific. Figure 20 is courtesy of Radford University and Lora Gordon. Figure 23 is courtesy of Michael Carroll and the Planetary Organisation. Figure 25 is courtesy of IoP and Miguel Alcubierre Moya. Figure 27 is courtesy of Geoffrey Landis. Figure 30 is courtesy of ligo. Figure 31 is courtesy of Antares - F. Montanet ccpm/in2p3/cnrs - Université Mediterranée. Figures 33 and 34 are both courtesy of the seti Institute, used by permission. Figure 40 is courtesy of Michael Daly, Uniformed Services University of the Health Sciences. Figure 41 is courtesy of cern. Figure 43 is © Frederik Ramm (see http://www.remote.org/frederik/culture/berlin/).

Figure 53 is courtesy of nasa/P. J. T. Leonard, and Figure 54 is courtesy of nasa/Don Davis. Figure 55 is courtesy of noaa; photographer Michael Van Woert. Figure 56 is courtesy of noaa. The four images in Figure 62 are courtesy of Prof. Dr. K. O. Stetter and Dr. R. Rachel, Universität Regensburg, Mikrobiologie; © University of Regensburg. Figure 64 is courtesy of the Wellcome Trust. Figure 67 is © US Department of Energy Human Genome Project. Figure 69 is © Arizona State University, photograph by Alan Riggs. Figure 71 is courtesy of Creswell Crags, © Creswell Heritage Trust.

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