Black holes, wormholes & time machines

281 Pages·1999·1.03 MB·English

by  Jim Al-Khalili

B H
L A C K O L E S
W
O R M H O L E S
& T M
I M E A C H I N E S
J A -K
IM L HALILI
University of Surrey
Institute of Physics Publishing
Bristol and Philadelphia
B H
L A C K O L E S
W
O R M H O L E S
& T M
I M E 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.
(cid:1)c IOPPublishingLtd1999
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To Julie, David and Kate
C O N T E N T S
PREFACE ix
ACKNOWLEDGMENTS xiii
INTRODUCTION xv
SPACE
1 THE 4TH DIMENSION 3
Todowithshapes •Whatisspace? •2Dworldand2D’ers •
Curvedspace •Istherereallyafourthdimension?
2 MATTERS OF SOME GRAVITY 22
Apples and moons • Einstein’s gravity • Free fall • Rubber
space •Twinkle,twinkle •Cookingtheelements •Champagne
supernovaeinthesky
3 THE UNIVERSE 41
The night sky • How big is the Universe? • The expanding
Universe•Hubble,bubble...•Spaceisstretching•DidtheBig
Bangreallyhappen? •Theedgeofspace •Acloseduniverse •
Anopenuniverse•WhatshapeistheUniversethen? •Invisible
matter•1998:abigyearincosmology•IstheUniverseinfinite?
•Whyisitdarkatnight? •BeforetheBigBang? •Summary
4 BLACK HOLES 78
Moretolightthanmeetstheeye! •Invisiblestars •Beyondthe
horizon •Aholethatcanneverbefilled •Spinningblackholes
•Fallingintoablackhole •Toseeablackhole •Notsoblack
afterall •Whiteholes
vii
BLACK HOLES, WORMHOLES & TIME MACHINES
TIME
5 TIMES ARE CHANGING 111
Whatistime? •Whoinventedtime? •Thefirstmoment •
Doestimeflow? •Somethingcalledentropy •Arrowsoftime
•StephenHawkinggetsitwrong •Apossiblesolution
6 EINSTEIN’S TIME 139
Whatissospecialaboutspecialrelativity? •Thetwofacesof
light •Thoughtexperimentsandbrainteasers •Slowingdown
time •Shrinkingdistances •Light—theworldspeedrecord •
Whentimerunsbackwards •Littlegreenmen •Fastforwardto
thefuture •Spacetime—thefutureisoutthere •Gravitational
times
7 TIME TRAVEL PARADOXES 174
TheTerminatorparadox •Tryingtosavethedinosaurs •Mona
Lisa’ssister •Nowayout? •Paralleluniverses •Whereare
allthetimetravellers?
TIME MACHINES
8 WORMHOLES 195
Abridgetoanotherworld •Alicethroughthelookingglass •
Whensciencefactmetsciencefiction •Wormholes—keeping
thestargateopen •Visitingaparalleluniverse
9 HOW TO BUILD A TIME MACHINE 216
Time loops • The Tipler time machine • Cosmic string
time machines • A recipe for a wormhole time machine •
Insurmountableproblems?
10 WHAT DO WE KNOW? 240
Themotherofalltheories •Theendoftheoreticalphysics •
Astronomyversusastrology •Thefascinationofscience
BIBLIOGRAPHY 254
INDEX 259
viii