The Book of The Universes by the same author Theories of Everything The Book of Universes The Left Hand of Creation (with Joseph Silk) L’Homme et le Cosmos (with Frank J. Tipler) John D. Barrow The Anthropic Cosmological Principle (with Frank J. Tipler) The Anthropic Cosmological Principle (with Frank J. Tipler) The World within the World The Artful Universe Pi in the Sky Perché il mondo è matematico? Impossibility The Origin of the Universe Between Inner Space and Outer Space The Universe that Discovered Itself The Book of Nothing The Constants of Nature: From Alpha to Omega The Infinite Book: A Short Guide to the Boundless, Timless and Endless New Theories of Everything Cosmic Imagery: Key Images in the History of Science 100 Essential Things You Didn’t Know THE BODLEY HEAD You Didn’t Know LONDON Published by The Bodley Head 2011 To Tilly 2 4 6 8 10 9 7 5 3 1 For whom there are many universes to come Copyright © John D. Barrow 2011 John D. Barrow has asserted his right under the Copyright, Designs and Patents Act 1988 to be identified as the author of this work This book is sold subject to the condition that it shall not, by way of trade or otherwise, be lent, resold, hired out, or otherwise circulated without the publisher’s prior consent in any form of binding or cover other than that in which it is published and without a similar condition, including this condition, being imposed on the subsequent purchaser. First published in Great Britain in 2010 by The Bodley Head Random House, 20 Vauxhall Bridge Road, London sw1v 2sa www.bodleyhead.co.uk www.rbooks.co.uk Addresses for companies within The Random House Group Limited can be found at: www.randomhouse.co.uk/offices.htm The Random House Group Limited Reg. 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Our paper procurement policy can be found at www.rbooks.co.uk/environment Typeset by Palimpsest Book Production Limited, Falkirk, Stirlingshire Printed and bound in Great Britain by Clays Ltd, St Ives PLC Contents Preface 00 1: Being in the Right Place at the Right Time 00 Two men walking 00 Funny things, universes 00 The importance of place 00 Aristotle’s spherical universe 00 Ptolemy’s ‘Heath Robinson’ universe 00 Copernican revolutions 00 2: The Earnestness of Being Important 00 Special times and special places 00 Democratic laws 00 The changing Universe 00 The nebular hypothesis 00 Life in an Edwardian universe 00 The decaying Universe 00 Karl Schwarzschild: the man who knew too much 00 3: Einstein’s Universes 00 Completing a Copernican vision 00 Einstein’s insight 00 A digression 00 The creation of Einstein’s universe of motionless matter 00 The creation of a second universe: de Sitter’s universe of matterless motion 00 viii The Book of Universes Contents i Friedmann’s universes of matter in motion 00 8: The Beginning for Beginners 00 Lemaître’s universes 00 Singular universes 00 The universe of Einstein and de Sitter 00 Which universes are singular? 00 Tolman’s oscillating universe 00 Cold and tepid universes 00 Lemaître and Tolman’s kinky universe 00 An unexpectedly simpler universe 00 Milne’s universe (and Newton’s universes) 00 And a unified way of thinking 00 4: Unexpected Universes: the Rococo Period 00 9: Brave New Worlds 00 Fractal universes 00 Asymmetric universes 00 Dr Kasner’s universe 00 Problem universes 00 Dirac’s universe – where gravity decays 00 Inflationary universes 00 Einstein and Rosen’s undulating universe 00 Chaotic inflationary universes 00 Eternal inflationary universes 00 5: Something Completely Different 00 Suddenly, the universe seems simpler again 00 A Swiss-cheese universe 00 The many universes run out of control 00 Perturbed universes 00 Schrödinger’s universe 00 10: Post-Modern Universes 00 Gödel’s spinning universe 00 Random universes 00 Probable universes 00 6: The Steady Statesmen Come and Go with a Bang 00 Anthropic universes 00 A universe that always was, is and is to come 00 Possible universes 00 A table-top universe 00 Home-made universes 00 The electric universe 00 Naturally selected universes 00 Hot universes 00 Fake universes 00 Universes where nothing is original 00 7: Universes, Warts and All 00 Boltzmann’s universe 00 Turbulent universes 00 11: Fringe Universes 00 Distorted universes: from one to nine 00 Smooth universes and a new observational window 00 Wrap-around universes 00 Chaotic universes 00 Quantum universes 00 Mixmaster universes 00 A self-creating universe 00 Magnetic universes 00 Colliding universes 00 The universes of Brans and Dicke 00 The dying of the light 00 Matter–antimatter universes 00 Hyperuniverses 00 12: The Runaway Universe 00 The best-buy universe 00 The preposterous universe 00 The puzzling universe 00 Preface (to come) Notes 000 Index 000 ii The Book of Universes Preface iii Preface to follow Preface to follow iv The Book of Universes Preface v Preface to follow Preface to follow vi The Book of Universes Preface to follow 1 Being in the Right Place at the Right Time I know it’s all in our minds, but a mind is a powerful thing. Colin Cotterill1 two men walking I am always surprised when a young man tells me he wants to work at cosmology; I think of cosmology as something that happens to one, not something one can choose. William H. McCrea2 The old gentleman walking down the street looked the same as ever – distinguished but slightly dishevelled, in a Bohemian style, a slow-walking European on an American main street, sad-faced, purposeful but not quite watching where he was going, always catching the attention of the locals as he made his way politely through the shoppers and the contra-flow of students late for lectures. Everyone seemed to know who he was but he avoided everyone’s gaze. Today, he had a new companion, very tall and stockily built, a little the worse for wear, untidy but in a different way to his companion. They were both deep in conversation as they made their way, walking and talking, oblivious of the shop windows beside them. The older man listened thoughtfully, sometimes frowning gently; his younger companion enthusiastically pressing his point, occasionally gesticulating wildly, talking incessantly. Neither spoke native English but their accents were quite different, revealing resonances with many places. Intent on crossing the street, they stopped, lingering at the kerbside as the traffic passed. The traffic lights changed and they 2 The Book of Universes The Book of Universes 3 continued quietly across the street, both momentarily concentrating on exists? When you draw up the list of all those things to include in ‘every- light, sound and relative motion. Suddenly, something happened. The thing’ you start to wonder about those ‘things’ that the physicists call taller man started to say something again, making a dart of his hand. the ‘laws of Nature’ and other intangibles like space and time. Although The traffic was moving again now but the old man had stopped, dead you can’t touch or see them, you can feel their effects, they seem pretty in his tracks, oblivious to the cars and the hurrying pedestrians. His important and they seem to exist – a bit like the rules of football – and companion’s words had consumed his thoughts entirely. The cars roared we had better throw them in as well. And what about the future and past on both sides leaving the two of them marooned in their midst like the past? Just focusing on what exists now seems a bit exclusive. And if a human traffic island. The old man was deep in thought, the younger we include everything that has ever existed as part of the universe, why one reiterating his point. Eventually, resuming contact with the moving not include the future as well? This seems to leave us with the definition world around them, but forgetful of where they had been going, the that the universe is everything that has existed, does exist and will ever older man led them silently towards the pavement – the one they had exist. stepped off a minute ago – and they walked and talked their way from If we were feeling really pedantic we might take an even grander whence they had come, lost in this new thought. view of the universe, which includes not only everything that can The two men had been talking about universes.3 The place was exist but also everything that could exist – and finally, even that which Princeton, New Jersey, and the time was during the Second World cannot exist. Some medieval philosophers5 were drawn to this sort of War. The younger man was George Gamow, or ‘Gee-Gee’ to his completeness, adding everything that has existed, does exist and will friends, a Russian émigré to the United States. The older man was not exist to the catalogue of what was, is and will be. This approach Albert Einstein. Einstein had spent the previous thirty years showing seems bent upon creating problems in an area where there are enough how we could understand the behaviour of whole universes with already. Yet recently it has re-emerged in modern studies of the simple maths. Gamow saw that those universes must have had a past universe, albeit in a slightly different guise.