A DIFFERENT APPROACH TO COSMOLOGY This is a different kind of book about cosmology, a ®eld of major interest to professional astronomers, physicists, and the general public. All research in cosmology adopts one model of the universe, the hot big-bang model. But Fred Hoyle, Geoffrey Burbidge and Jayant Narlikar take a different approach. Starting with the beginnings of modern cosmology, they then conduct a wide ranging and deep review of the observations made from 1945 to the present day. Here they challenge many conventional interpretations. The latter part of the book presents the authors' own account of the present status of observations and how they should be explained. The controversial theme is that the dependency on the hot big-bang model has led to an unwarranted rejection of alternative cosmological models. Writing from the heart, with passion and punch, these three cosmologists make a powerful case for viewing the universe in a different light. Sir Fred Hoyle held the Plumian Chair of Astronomy at the University of Cambridge 1958±72. Geoffrey Burbidge is at the Center for Astrophysics and Space Sciences, University of California, San Diego. He has held positions at the California Institute of Technology, the University of Chicago, and Harvard University and was Director of the Kitt Peak National Observatory 1978±84. Jayant Narlikar is with the Inter-University Centre for Astronomy and Astrophysics, Pune, India.

A DIFFERENT APPROACH TO COSMOLOGY From a static universe through the big bang towards reality F. HOYLE G. BURBIDGE Center for Astrophysics and Space Sciences, University of California, San Diego

AND J. V. NARLIKAR Inter-University Centre for Astronomy and Astrophysics, Pune

CAMBRIDGE UNIVERSITY PRESS Cambridge, New York, Melbourne, Madrid, Cape Town, Singapore, São Paulo Cambridge University Press The Edinburgh Building, Cambridge CB2 2RU, UK Published in the United States of America by Cambridge University Press, New York www.cambridge.org Information on this title: www.cambridge.org/9780521662239 © F. Hoyle, G. Burbidge and J.V. Narlikar 2000 This publication is in copyright. Subject to statutory exception and to the provisions of relevant collective licensing agreements, no reproduction of any part may take place without the written permission of Cambridge University Press. First published 2000 Reprinted 2000(twice), 2001 This digitally printed first paperback version 2005 A catalogue record for this publication is available from the British Library Library of Congress Cataloguing in Publication data Hoyle, Fred, Sir. A different approach to cosmology: from a static universe through the big bang towards reality / F. Hoyle, G. Burbidge and J.V. Narlikar. p. cm. Includes bibliographical references. ISBN 0 521 66223 0 1. Cosmology. I. Burbidge, Geoffrey, R. II. Narlikar, Jayant Vishnu, 1938– . III. Title. QB981.H754 2000 523.1–dc21 99-15821 CIP ISBN-13 978-0-521-66223-9 hardback ISBN-10 0-521-66223-0 hardback ISBN-13 978-0-521-01926-2 paperback ISBN-10 0-521-01926-5 paperback

Contents

Preface Acknowledgements Chapter Chapter Chapter Chapter

1 2 3 4

Chapter 5 Chapter 6 Chapter 7 Chapter 8 Chapter 9 Chapter 10 Chapter 11 Chapter 12 Chapter Chapter Chapter Chapter

13 14 15 16

page vii x

Introduction 1 Early relativistic cosmology 5 The observational revolution 17 The observational trail 1931±56, the determination of Ho and the age dilemma 27 Changing times, 1945±65: new techniques and new people 45 The extension of the redshift±apparent magnitude diagram to faint galaxies 1956±95 55 The classical steady-state cosmological model and its observational tests 65 The cosmic microwave background ± an historical account 79 The origin of the light elements 95 A new primordial calculation of Y and of D/H 107 The new observational evidence and its interpretation: (a) quasi-stellar objects and redshifts 117 The new observational evidence and its interpretation: (b) ejection phenomena and energetics 163 Modern Friedmann cosmology 169 Standard cosmology 175 New cosmological models 189 The observations explained in terms of the quasi-steady-state model 197 v

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Chapter 17 The intrinsic redshift problem Chapter 18 Creation centers and black holes Chapter 19 Modern observations of faint galaxies and related objects Chapter 20 The large-scale distribution of matter Chapter 21 A brief account of the radiation ®elds in the universe ± the observations and their interpretation Chapter 22 A summary of the material contained in the previous chapters Chapter 23 Some unsolved problems References Index

229 239 251 275

303 311 321 339 351

Preface

This is a different kind of book about cosmology. In the past 10 or 15 years, there has been a great spate of textbooks, monographs and popular books on this subject. There is no question but that cosmology has developed into a major topic of study for astronomers, physicists and laymen alike. The reasons for this are not hard to ®nd. We are all keenly interested in where we came from and where we are going, and cosmology, the study of the whole universe, is supposed to give us the answers to these basic questions. In this sense it has much the same attraction for many as does religion. Both have been dominated in the past by a small number of facts and large measures of belief. Some genuine progress in cosmology has come, however, mostly from advances in observational astronomy leading to new information being obtained at an increasing rate in the past 40 years. These advances have nearly all come from advances in technology at optical wavelengths, and investigations of the universe at radio, infrared, and ultraviolet frequencies, and at X-ray and -ray energies. Naturally this has led to a huge increase in the number of scientists in the ®eld, and to much larger sums of money being required. This is inevitable, but it has a downside. For example, physicists with no background in astronomy have moved into cosmology in large numbers. However, without knowledge of what has gone before, there is always a lack of perspective, and this shows up very strongly when any attempt is made to consider alternative explanations of what are often considered to be well-established facts. Also, astrophysics and cosmology is now big science, which requires large sums of money to support it. The major sources of funds are National Government Agencies, such as the National Science Foundation and the National Aeronautics and Space Administration in the USA. The agencies providing the money then make a considerable impact on the way we do science. For example, if you are funded by NASA, you are vii

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Preface

expected to engage in a great deal of publicity and media hype. A fact of life which is well known to the professionals, but which has probably not yet been digested by the world at large, is that the effort and propaganda required to get a major instrument funded ± say the Hubble Space Telescope, or the Cosmic Background Explorer Satellite (COBE) ± requires that before the instruments can be built, extravagant claims must be made about what we shall ®nd. Not surprisingly, when these instruments eventually work, we get a succession of even stronger claims to the effect that what was expected has indeed been found. Some of the claims are amazing even to those who work in the ®eld, e.g. about the microwave background radiation and its ¯uctuations: `They have found the Holy Grail of Cosmology', Dr Michael Turner, University of Chicago. `Well, if you are a religious person, it's like seeing the face of God', Dr George Smoot, University of California, Berkeley.

In an era when serious scientists can take such an approach, there is no room for the discovery of phenomena which are not already expected. Those few scientists who want to look for things that they may not be able to explain simply cannot get telescope time. The people who assign observing time on the telescopes using the so-called peer review system demand that you explain beforehand what you will ®nd. And those who do ®nd such phenomena by accident mostly can be relied on to be so conformist that they put them aside. And, of course, if you know little of the history of science, and particularly if you are a particle physicist, you are con®dent that there is nothing to learn from astronomy about fundamental physics. For many reasons, and these are only some of them, all the books on cosmology written in the present era focus on one model of the universe ± the currently popular hot big-bang model. While they may sometimes pay lip service to alternatives, anyone who reads any of these books can be left in no doubt as to the truth, as it is seen by the prestigious author. In this monograph, we use a different approach. We start at the true beginning of the modern era ± around 1914 ± and give an historical account of how the subject has progressed. In the middle chapters we discuss the sequence of events from about 1945 to about 1965, and the newer observational results and the developments of the past 30 years. Much of what has gone on has not simply been due to advances in observation and theory. It has clearly been affected by the attitudes, personalities, prejudices and beliefs of the scientists who made the advances. Since we have often been involved personally in these advances (and retreats) alongside many who are, or have

Preface

ix

been, personal friends, our account of the past 40 years or more of history will re¯ect our own beliefs and prejudices as well as those of our colleagues. In the latter part of the book we give a full account of our own ideas. Then we turn to a review of the present observational situation and then a summary of the current state of affairs. Since we believe that there are many fundamental questions which remain unanswered, in the last chapter we describe several of the major unsolved problems.

Acknowledgements

This book has been written by three authors who normally live on three different continents. Thus while much of the work has been done by telephone and fax, a good deal of travel has been involved. In England we wish to thank Barbara Hoyle and Nicola Hoyle who have helped in many ways in Bournemouth. We also wish to thank Alex Boksenberg and Jasper Wall for hospitality afforded to us at the Royal Greenwich Observatory in the summers of 1996 and 1997. In India we have been given much help by the staff at IUCAA. Also two of us have been given much hospitality at Pune when we have been able to visit on several occasions. In the USA we have received much assistance from several people in La Jolla. In particular, Betty Travell at the Center for Astrophysics and Space Science who typed the whole of the manuscript in several drafts in 1996 and 1997. Without her the book would never have been completed. We also want to thank Kathy Steffen at CASS who has drawn or redrawn the bulk of the diagrams and the ®gures, Del Hewitt who made many of them, and Kate Ericson who helped us extensively in 1998. Margaret Burbidge has contributed in many ways in the latter stage and has done much editing and proofreading. We also wish to thank many astronomers for providing us with illustrations and diagrams. In particular we wish to thank Chip Arp from the Max-Planck-Institut fuÈr Astrophysik in Munich for providing material and lots of enthusiasm. We thank John Bahcall, from the Institute for Advanced Study, John Huchra from the Harvard-Smithsonian Astrophysical Observatory, Nigel Sharp from Kitt Peak National Observatory, Allan Sandage and John Bedke from the Carnegie Observatories and Space Telescope Science Institute, Arthur Wolfe and Lisa Storrie-Lombardi from UCSD, and Charles Bennett from NASA/Goddard for providing us with many remarkable illustrations. xi

1 Introduction

Both Newton and Einstein thought that the universe must be static on the large scale and also homogeneous and isotropic. However, until early in the twentieth century there was no understanding of the scale of the universe nor any evidence that anything lay beyond the Milky Way. By the latter part of the nineteenth century, it was known that there were two kinds of nebulae ± spiral structure had ®rst been detected in one type in Messier 51, by Lord Rosse in 1855, and there was some speculation that such systems might be very distant Milky Way like objects. However by 1905, in her well-known popular book The System of the Stars, Agnes Clerke1, basing her remarks on the results and conclusions of professional astronomers, stated with some con®dence: The question whether nebulae are external galaxies hardly any longer needs discussion. It has been answered by the progress of research. No competent thinker, with the whole of the available evidence before him, can now, it is safe to say, maintain any single nebula to be a star system of co-ordinate rank with the Milky Way. A practical certainty has been attained that the entire contents, stellar and nebula, of the sphere belong to one mighty aggregation, and stand in ordered mutual relations within the limits of one all embracing scheme.

It would be as well, whenever cosmologists meet nowadays to discuss their certainty over the state of the universe, that they should recall these words of Agnes Clerke, who was widely regarded in her time as a gifted expositor of the views of the then-accepted trade union of competent thinkers. Ten years after Agnes Clerke's summary, in 1915, Einstein2 formulated his equations of gravitation and soon felt the need to apply them to the universe as a whole. Since the universe is the largest system of matter imaginable and also in reality, he considered that a theory of gravitation should say how this system would behave. Newton's attempts to solve a similar problem had 1

2

Introduction

failed: a model of a static universe in stable equilibrium had not been possible. In his pioneering paper on cosmology, Einstein devoted the initial part to the Newtonian problem. His requirements on a realistic model led him to postulate that the gravitational potential of matter should tend to a constant at spatial in®nity. This led him to a spherically symmetric distribution with the density tapering off at in®nity faster than the inverse square of distance from the centre of symmetry. By applying Boltzmann's law of gas distribution to his matter, Einstein was then able to argue that the density had to be zero everywhere, if it was to vanish at in®nity. He then showed that if he modi®ed the Newtonian force law with the addition of a cosmological term, adding a force of repulsion in proportion to distance, the above dif®culty disappeared. Taking his cue from the Newtonian problem he then went over to his theory of relativity and found that, and we quote again: The conclusion I shall arrive at is that the ®eld equations of gravitation which I have championed hitherto still need a slight modi®cation, so that on the basis of the general theory of relativity those fundamental dif®culties are avoided which have been set forth as confronting the Newtonian theory.

In other words, his basic considerations were entirely theoretical and not motivated by what the real universe might be like. When one inserts the cosmological term into the ®eld equations of general relativity, and uses the assumptions of homogeneity and isotropy in addition to the assumption of a static universe, the following conclusions emerge unequivocally. (i) To get a universe of constant positive density, the cosmological constant must be positive (i.e., it must correspond to a repulsive force). (ii) The universe must be closed and have a constant positive curvature.

Einstein admitted in his paper that in the actual universe `the curvature of space is variable in time and place, according to the distribution of matter, but we may roughly approximate to it by means of a spherical space'. The idea of a ®nite and closed universe in which the density of matter determines the radius of curvature of the spherical space was entirely in keeping with Einstein's expectations that the matter±energy distribution should determine the spacetime geometry. Being then under the in¯uence of Ernst Mach, he considered this a demonstration of Mach's ideas and hoped that his solution would turn out to provide a unique and hence an authentic picture of the universe. In concluding his paper Einstein underscored his priorities for a cosmological model:

References

3

. . . this view is logically consistent, and from the standpoint of the general theory of relativity lies nearest at hand. Whether, from the standpoint of present astronomical knowledge, it is tenable, will not be discussed here.

His reading of the astronomical knowledge of his time was that we live in a static universe. He seemed aware that he could get dynamical models with his equations without the cosmological term but concluded as follows: It is to be emphasized, however, that a positive curvature of space is given by our results, even if the supplementary term is not introduced. That term is necessary only for the purpose of making possible a quasi-static distribution of matter, as required by the fact of the small velocities of the stars.

Now we turn to the theory in some detail. References Chapter 1 1. Clerke, Agnes M. 1905, The System of the Stars (London, Adam & Charles Black), p. 349. 2. Einstein, A. 1915, Preuss. Akad. Wiss. Berlin, Sitzber, 844.