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BLACK HOLES WO R M H O L E S & T
I M E
M
A C H I N E S
About the Author Jim Al-Khalili was born in 1962 and works as a theoretical physicist at the University of Surrey in Guildford. He is a pioneering popularizer of science and is dedicated to conveying the wonder of science and to demystifying its frontiers for the general public. He is an active member of the Public Awareness of Nuclear Science European committee. His current research is into the properties of new types of atomic nuclei containing neutron halos. He obtained his PhD in theoretical nuclear physics from Surrey in 1989 and, after two years at University College London, returned to Surrey as a Research Fellow before being appointed lecturer in 1992. He has since taught quantum physics, relativity theory, mathematics and nuclear physics to Surrey undergraduates. He is married with two young children and lives in Portsmouth in Hampshire.
BLACK HOLES WO R M H O L E S & T
I M E
M
A C H I N E S
JIM AL-KHALILI University of Surrey
Institute of Physics Publishing Bristol and Philadelphia
c IOP Publishing Ltd 1999 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 permission of the publisher. Multiple copying is permitted in accordance with the terms of licences issued by the Copyright Licensing Agency under the terms of its agreement with Universities UK (UUK). British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library. ISBN 0 7503 0560 6 Library of Congress Cataloging-in-Publication Data are available Reprinted with corrections 2000 Reprinted 2001 (twice), 2003
Production Editor: Al Troyano Production Control: Sarah Plenty and Jenny Troyano Commissioning Editor: Michael Taylor Editorial Assistant: Victoria Le Billon Cover Design: Kevin Lowry Marketing Executive: Laura Serratrice Published by Institute of Physics Publishing, wholly owned by The Institute of Physics, London Institute of Physics Publishing, Dirac House, Temple Back, Bristol BS1 6BE, UK US Office: Institute of Physics Publishing, Suite 929, The Public Ledger Building, 150 South Independence Mall West, Philadelphia, PA 19106, USA Typeset in TEX using the IOP Bookmaker Macros First printed in the UK by J W Arrowsmith Ltd, Bristol Reprinted in the UK by MPG Books Ltd, Bodmin, Cornwall
To Julie, David and Kate
CONTENTS
P R E FA C E
ix
ACKNOWLEDGMENTS INTRODUCTION
xiii xv
SPACE 1
THE 4TH DIMENSION
3
To do with shapes • What is space? • 2Dworld and 2D’ers • Curved space • Is there really a fourth dimension?
2
M A T T E R S O F S O M E G R AV I T Y
22
Apples and moons • Einstein’s gravity • Free fall • Rubber space • Twinkle, twinkle • Cooking the elements • Champagne supernovae in the sky
3
THE UNIVERSE
41
The night sky • How big is the Universe? • The expanding Universe • Hubble, bubble . . . • Space is stretching • Did the Big Bang really happen? • The edge of space • A closed universe • An open universe • What shape is the Universe then? • Invisible matter • 1998: a big year in cosmology • Is the Universe infinite? • Why is it dark at night? • Before the Big Bang? • Summary
4
BLACK HOLES
78
More to light than meets the eye! • Invisible stars • Beyond the horizon • A hole that can never be filled • Spinning black holes • Falling into a black hole • To see a black hole • Not so black after all • White holes
vii
BLACK HOLES, WORMHOLES & TIME MACHINES
TIME 5
TIMES ARE CHANGING