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  Cosmology: A Very Short Introduction

  ‘a fast track through the history of our endlessly fascinating Universe,

  from then to now’

  J. D. Barrow, Cambridge University

  ‘In a clear and elegant style, Coles succeeds in conveying the gist of some of the deepest concepts in Physics … that underlie our understanding of the cosmos. This concise, yet up-to-date, account of cosmic history makes for compelling reading for anyone who has ever wondered about how our universe works.’

  Carlos Frenk, University of Durham

  ‘presents a wonderfully broad range of concepts in a clear and readable way [and] gives a vivid picture of the confusion and excitement of research in progress.’

  P. J. E. Peebles, Princeton University

  ‘a pleasure to read’

  New Scientist

  * * *

  VERY SHORT INTRODUCTIONS are for anyone wanting a stimulating and accessible way in to a new subject. They are written by experts, and have been published in more than 25 languages worldwide.

  The series began in 1995, and now represents a wide variety of topics in history, philosophy, religion, science, and the humanities. Over the next few years it will grow to a library of around 200 volumes – a Very Short Introduction to everything from ancient Egypt and Indian philosophy to conceptual art and cosmology.

  * * *

  Very Short Introductions available now:

  ANCIENT PHILOSOPHY

  Julia Annas

  THE ANGLO-SAXON AGE

  John Blair

  ANIMAL RIGHTS David DeGrazia

  ARCHAEOLOGY Paul Bahn

  ARCHITECTURE

  Andrew Ballantyne

  ARISTOTLE Jonathan Barnes

  ART HISTORY Dana Arnold

  ART THEORY Cynthia Freeland

  THE HISTORY OF

  ASTRONOMY Michael Hoskin

  ATHEISM Julian Baggini

  AUGUSTINE Henry Chadwick

  BARTHES Jonathan Culler

  THE BIBLE John Riches

  BRITISH POLITICS

  Anthony Wright

  BUDDHA Michael Carrithers

  BUDDHISM Damien Keown

  CAPITALISM James Fulcher

  THE CELTS Barry Cunliffe

  CHOICE THEORY

  Michael Allingham

  CHRISTIAN ART Beth Williamson

  CLASSICS Mary Beard and

  John Henderson

  CLAUSEWITZ Michael Howard

  THE COLD WAR

  Robert McMahon

  CONTINENTAL PHILOSOPHY

  Simon Critchley

  COSMOLOGY Peter Coles

  CRYPTOGRAPHY

  Fred Piper and Sean Murphy

  DADA AND SURREALISM

  David Hopkins

  DARWIN Jonathan Howard

  DEMOCRACY Bernard Crick

  DESCARTES Tom Sorell

  DRUGS Leslie Iversen

  THE EARTH Martin Redfern

  EGYPTIAN MYTHOLOGY

  Geraldine Pinch

  EIGHTEENTH-CENTURY

  BRITAIN Paul Langford

  THE ELEMENTS Philip Ball

  EMOTION Dylan Evans

  EMPIRE Stephen Howe

  ENGELS Terrell Carver

  ETHICS Simon Blackburn

  THE EUROPEAN UNION

  John Pinder

  EVOLUTION

  Brian and Deborah Charlesworth

  FASCISM Kevin Passmore

  THE FRENCH REVOLUTION

  William Doyle

  FREUD Anthony Storr

  GALILEO Stillman Drake

  GANDHI Bhikhu Parekh

  GLOBALIZATION

  Manfred Steger

  HEGEL Peter Singer

  HEIDEGGER Michael Inwood

  HINDUISM Kim Knott

  HISTORY John H. Arnold

  HOBBES Richard Tuck

  HUME A. J. Ayer

  IDEOLOGY Michael Freeden

  INDIAN PHILOSOPHY

  Sue Hamilton

  INTELLIGENCE Ian J. Deary

  ISLAM Malise Ruthven

  JUDAISM Norman Solomon

  JUNG Anthony Stevens

  KANT Roger Scruton

  KIERKEGAARD Patrick Gardiner

  THE KORAN Michael Cook

  LINGUISTICS Peter Matthews

  LITERARY THEORY

  Jonathan Culler

  LOCKE John Dunn

  LOGIC Graham Priest

  MACHIAVELLI Quentin Skinner

  MARX Peter Singer

  MATHEMATICS Timothy Gowers

  MEDIEVAL BRITAIN

  John Gillingham and

  Ralph A. Griffiths

  MODERN IRELAND

  Senia Pašeta

  MOLECULES Philip Ball

  MUSIC Nicholas Cook

  NIETZSCHE Michael Tanner

  NINETEENTH-CENTURY

  BRITAIN Christopher Harvie and

  H. C. G. Matthew

  NORTHERN IRELAND

  Marc Mulholland

  PAUL E. P. Sanders

  PHILOSOPHY Edward Craig

  PHILOSOPHY OF SCIENCE

  Samir Okasha

  PLATO Julia Annas

  POLITICS Kenneth Minogue

  POLITICAL PHILOSOPHY

  David Miller

  POSTCOLONIALISM

  Robert Young

  POSTMODERNISM

  Christopher Butler

  POSTSTRUCTURALISM

  Catherine Belsey

  PREHISTORY Chris Gosden

  PRESOCRATIC PHILOSOPHY

  Catherine Osborne

  PSYCHOLOGY Gillian Butler and

  Freda McManus

  QUANTUM THEORY

  John Polkinghorne

  ROMAN BRITAIN Peter Salway

  ROUSSEAU Robert Wokler

  RUSSELL A. C. Grayling

  RUSSIAN LITERATURE

  Catriona Kelly

  THE RUSSIAN REVOLUTION

  S. A. Smith

  SCHIZOPHRENIA

  Chris Frith and Eve Johnstone

  SCHOPENHAUER

  Christopher Janaway

  SHAKESPEARE Germaine Greer

  SOCIAL AND CULTURAL

  ANTHROPOLOGY

  John Monaghan and Peter Just

  SOCIOLOGY Steve Bruce

  SOCRATES C. C. W. Taylor

  SPINOZA Roger Scruton

  STUART BRITAIN John Morrill

  TERRORISM Charles Townshend

  THEOLOGY David F. Ford

  THE TUDORS John Guy

  TWENTIETH-CENTURY

  BRITAIN Kenneth O. Morgan

  WITTGENSTEIN A. C. Grayling

  WORLD MUSIC Philip Bohlman

  Available soon:

  AFRICAN HISTORY

  John Parker and Richard Rathbone

  ANCIENT EGYPT Ian Shaw

  THE BRAIN Michael O’Shea

  BUDDHIST ETHICS

  Damien Keown

  CHAOS Leonard Smith

  CHRISTIANITY Linda Woodhead

  CITIZENSHIP Richard Bellamy

  CLASSICAL ARCHITECTURE

  Robert Tavernor

  CLONING Arlene Judith Klotzko

  CONTEMPORARY ART

  Julian Stallabrass

  THE CRUSADES

  Christopher Tyerman

  DERRIDA Simon Glendinning

  DESIGN John Heskett

  DINOSAURS David Norman

  DREAMING J. Allan Hobson

  ECONOMICS Partha Dasgupta

  THE END OF THE WORLD

  Bill McGuire

  EXISTENTIALISM Thomas Flynn

  THE FIRST WORLD WAR

  Michael Howard

  FREE WILL Thomas Pink

  FUNDAMENTALISM

  Malise Ruthven
/>   HABERMAS Gordon Finlayson

  HIEROGLYPHS

  Penelope Wilson

  HIROSHIMA B. R. Tomlinson

  HUMAN EVOLUTION

  Bernard Wood

  INTERNATIONAL RELATIONS

  Paul Wilkinson

  JAZZ Brian Morton

  MANDELA Tom Lodge

  MEDICAL ETHICS

  Tony Hope

  THE MIND Martin Davies

  MYTH Robert Segal

  NATIONALISM Steven Grosby

  PERCEPTION Richard Gregory

  PHILOSOPHY OF RELIGION

  Jack Copeland and Diane Proudfoot

  PHOTOGRAPHY

  Steve Edwards

  THE RAJ Denis Judd

  THE RENAISSANCE

  Jerry Brotton

  RENAISSANCE ART

  Geraldine Johnson

  SARTRE Christina Howells

  THE SPANISH CIVIL WAR

  Helen Graham

  TRAGEDY Adrian Poole

  THE TWENTIETH CENTURY

  Martin Conway

  For more information visit our web site

  www.oup.co.uk/vsi

  Peter Coles

  COSMOLOGY

  A Very Short Introduction

  Great Clarendon Street, Oxford OX2 6DP

  Oxford University Press is a department of the University of Oxford.

  It furthers the University’s objective of excellence in research, scholarship,

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  Oxford is a registered trade mark of Oxford University Press

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  Published in the United States

  by Oxford University Press Inc., New York

  © Peter Coles 2001

  The moral rights of the author have been asserted

  Database right Oxford University Press (maker)

  First published as an Oxford University Press paperback 2001

  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,

  without the prior permission in writing of Oxford University Press,

  or as expressly permitted by law, or under terms agreed with the appropriate

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  outside the scope of the above should be sent to the Rights Department,

  Oxford University Press, at the address above

  You must not circulate this book in any other binding or cover

  and you must impose this same condition on any acquirer

  British Library Cataloguing in Publication Data

  Data available

  Library of Congress Cataloging in Publication Data

  Data available

  ISBN 13: 978–0–19–285416–2

  ISBN 10: 0–19–285416–X

  5 7 9 10 8 6 4

  Typeset by RefineCatch Ltd, Bungay, Suffolk

  Printed in Great Britain by

  TJ International Ltd., Padstow, Cornwall

  Preface

  This book is an introduction to the ideas, methods, and results of scientific cosmology.

  The subject matter of cosmology is everything that exists. The entire system of things that is the Universe encompasses the very large and the very small, the astronomical scale of stars and galaxies and the microscopic world of elementary particles. Between these limits lies a complex hierarchy of structure and pattern that results from the interplay of forces and matter. And in the midst of all this we find ourselves.

  The aim of cosmology is to place all known physical phenomena within a single coherent framework. This is an ambitious goal, and significant gaps in our knowledge still remain. Nevertheless, there has been such rapid progress that many cosmologists regard this as something of a ‘Golden Age’. I have taken a roughly historical path through the subject to show how it has evolved, how it has drawn together many different conceptual strands along the way, and how new avenues for exploration have opened up with improvements in technology.

  It is a good time to write this kind of book. An emerging consensus about the form and distribution of matter and energy in the Universe suggests that a complete understanding of it all may be within reach. But interesting puzzles remain, and if history tells us anything it is that we should expect surprises!

  Contents

  List of illustrations

  1 A brief history

  2 Einstein and all that

  3 First principles

  4 The expanding Universe

  5 The Big Bang

  6 What’s the matter with the Universe?

  7 Cosmic structures

  8 A theory of everything?

  Epilogue

  Further reading

  Index

  List of illustrations

  1 The Babylonian God Marduk

  From The Mythology of All Races, ed. J. A. MacCulloch (Cooper Square, 1964); see Echoes of the Ancient Skies, E. C. Krupp, p. 68.

  2 Thought-experiment illustrating the equivalence principle

  From P. Coles, Einstein and the Birth of Big Science (Icon Books, 2000)

  3 The bending of light

  From P. Coles, Einstein and the Birth of Big Science (Icon Books, 2000)

  4 The curvature of space

  From P. Coles, Einstein and the Birth of Big Science (Icon Books, 2000)

  5 Open, flat, and closed spaces in two dimensions

  6 Hubble’s Law

  7 The Hubble diagram

  From Hubble (1929), Proceedings of Nat. Acad. Sci., 15, 168–173; see The Expanding Universe, R. C. Smith, p. 92

  8 Redshift

  9 The Hubble diagram updated

  10 The Hubble Space Telescope

  Space Telescope Science Institute

  11 Cepheids in M100

  Space Telescope Science Institute

  12 The age of the Universe

  13 The spectrum of the cosmic microwave background

  NASA and George Smoot

  14 Looking back in time

  15 Building blocks of matter

  Fermi National Accelerator Laboratory

  16 The Friedmann models

  17 The Coma cluster

  National Optical Astronomy Observatories

  18 Coma in X-rays

  High Energy Astrophysics Archive Research Center

  19 Gravitational lensing

  Space Telescope Science Institute

  20 The Andromeda Nebula

  Jason Ware

  21 The Lick Map

  Steve Maddox

  22 The 2dF galaxy redshift survey

  Steve Maddox and the 2dF Consortium

  23 The COBE ripples

  NASA and George Smoot

  24 The Hubble deep field

  The Virgo Consortium

  25 Simulation of structure formation

  Space Telescope Science Institute

  26 BOOMERANG

  The Boomerang Collaboration

  27 The flatness of space

  The Boomerang Collaboration

  28 A theory of everything

  29 Space–time foam

  From 300 Years of Gravity, ed. S. W. Hawking and W. Israel (Cambridge University Press, 1987), p. 625

  Chapter 1

  A brief history

  Cosmology is a relatively new branch of physical science. This is quite a paradoxical state of affairs, because among the questions cosmology asks are some of the most ancient that humanity has ever posed. Is the Universe infinite? Has it been around for ever? If not, how did it come into being? Will it ever come to an end? Since prehistoric times, humans have sought to build some kind of conceptual framewor
k for answering questions about the world and their relationship to it. The first such theories or models were myths that we nowadays regard as naive or meaningless. But these primitive speculations demonstrate the importance we as a species have always attached to thinking about the Universe. Today’s cosmologists use very different language and symbolism, but their motivation is largely the same as our distant ancestors. What I want to do in this chapter is briefly chart the historical development of cosmology ‘the subject’ and explain how some of the key ideas have evolved. I hope this will also provide a useful springboard into the other chapters in which I explore these key ideas in more detail.