The Fabric of Reality: The Science of Parallel Universes and Its Implications

402 Pages·1997·9.106 MB·English

by  David Deutsch

PENGUIN BOOKS
THE FABRIC OF REALITY
Borni nH aifIas,r aDealv,i Dde utscwha se ducataetdC ambridge Univer­
sitayn dO xforUdn iversHiet iysa. m embeorf t heQ uantuCmo mputation
andC ryptograRpehsye arGcrho upa tt heC larendLoanb orat,oO rxyford
UniversHiitspy a.p erosn q uantucmo mputatliaointd h ef oundatifoonrs
·
thafite lda,n dh ei sa na uthorointt yh et heoroyfp aralulneilv erses.
The Fabric of Reality
Praise for
"Fulolfr efreshoibnlgilqypu reo,v ocaitnisvieg .h.t.Qs u antumme chanics,
Deutsch inmsuisstbt est ,a kenno tj usats a predicttiovoelb ,u ta sa ne x­
planatfioorhn o wt hew orlrde alwloyr ks."
-GeorgJeo hnsoTnh,e New York Times
"DaviDde utscihsa deeplkyn owledgeparbolfee ssipohnyasli cwihsoth as
not rucwki thmy sticfaall asnea logies[ he.h].a .sb ecomteh em oste lo­
quenstp okesmoafnt heM anyU niverisnetse rpretoafqt uiaonnt ubme hav­
io,ra nd[ The Fabric of Reality] makest hitsh eme cohewrietnhst o me
well-thougvhite-w.osofe u pti stemoloofbg iyo,l ogeivcoallu tainodno ,ft he
theoorfyc omputati-oRni.c"h aDradw kins
"Int hel ibraorfpy h ysifcosrl aypeoDpeluet,s cbho'osk i su niqu.Ce orrec­
tioint:i sm ultiveerxsiaslt,ii nin ngn umeraubnliev ertsheaDste utsachr gues
exiaslto ngstihde'e r eauln'i vetrhsaept e oplpee rceiEvxep.l aintihnagat n,d
persuadtihnerg e adoefri tssc ienttirfiuctm ha,k etsh iwso rku niqu.e. t.h e
confidenwciet whh icDhe utscphr esehnitvssi ewasn,d t hea bsenocfec on­
desceijsiinoh ni ss tylaec,c essneosn scienttiosh tisss eemingallyi en
world(s)." -ALA Book list
"DaviDde utscihso neo fB ritaimno'ssto rigitnhailn k.eI rnst himsa jor
workh ec onfrotnhteds e epeqsute stioofne sx istehnecaedo n,c hallenging
traditinoontailo onfsr ealiwtiyt ha neww orldvitehwa itn terweaves
physibciso,l o,cg oymputianngd,p hilosopIhh ya.v enb'ete ns oi nspired
sincI ree aDdo uglHaosf stadtGeorde'l,s E scher, Bach."
- PauDla vieasu,t hoorfA bout Time: Ei1;stei11's
U11fi11ished Revolutio11
"Deutspcrho vidaem so deolf r ealtihtayit sa sp rovocaatsii vtie sc ompl.e x
. .A n. i ntellecsttuiamlullya rteianfdgo rt hes cience-laintdem roattie\ 'ated
layper.s..on.T hea uthoerx hib.i.ta.st horoukgnho wledogfhe i ssu bject
matt.e.r. I.n a fi elwdh ersec ientiinfiqcu icrhya llenngoetos n loyu ri mag-
inatibountb asiacs sumptiaobnosuo tu rp hysicwaolr ldt,h ivso lumper o­
videtsh ee ssentiinaflo rmatnieoend efdo rf utudreeb ates."
-Publishers Weekly

The Fabric of Reality
The Science of Parallel Universes­
and Its Implications
DAVID DEUTSCH
PENGUIN BOOK�
PENGUIN BOOKS
Publisbhyet dh eP enguGirno up
PenguPiunt naImn c3.7,5 H udsoSnt reet,
New YorkN,e w York1 0014U,. S.A.
PenguBiono kLst d2,7 W righLtasn eL,o ndoWn8 5TZ,E ngland
PenguBiono kAsu straLltidaR, i ngwooVdi,c torAiuas,t ralia
PenguBiono kCsa nadLat d1,0 A lcorAnv enue,
TorontOon,t ariCoa,n adMa4 V 3B2
PenguBiono k(sN .ZL.t)d 1,8 2-19W0a iraRuo ad,
Auckla1n0d, N ew Zealand
PenguBiono kLst dR,e gisteOrfefidc es:
HarmondsworMtihd,d lesEenxg,l and
Firpsutb lisihneG dr eaBtr itabiyAn l leLna neT heP enguPirne ss,
PenguBiono kLst d1.9 97
Firpsutb lisihnet dh eU niteSdt atoefsA mericbayA lleLna neT heP enguPirne ss,
ani mprionftV ikinPge nguian m,e mbeorf P enguPiunt naImn c1.9,9 7
PublisihneP de nguBiono k1s9 98
5 7 9 10 8 6
Copyri©g hDtaviDde utsc1h9,9 7
Allr ighrtess erved
THE LIBRARY OF CONGRESS HAS CATALOGUI
THE AMERICAN HARDCOVER EDITION AS FOLL•
DeutscDha,v id.
Thef abroifcr ealIi Dtayv iDde utsch.
p. cm.
Includbeisb liograrpehfiecraelna cnedis n dex.
ISBN0 -7139-90(6h1e-.9)
ISBN0 140 2.754X1 ( pbk.)
1.R ealit2y..P hysics-Philos3o.Lp ihfye.4. . C osmologyI..T itle.
QC6.4.R42D4189 97
530'.01-dc219 7-6171
Printientd h eU niteSdt atoefsA merica
Seti nM onotypSea bon
Figurdersa wbny N igeAln drews
Excepitnt heU niteSdt atoefsA merictah,ib so oki ss olsdu bjetcott h e
condittihoanit ts halnolt b,y w ayo ft radoero therwibsele e,n rte,- sohlidr,e d
outo,r o therwciisrec ulwaittehdo tuhtep ublishperri'ocsro nseinnta nyf ormo f
bindionrgc oveort hetrh atnh aitn w hiciht i sp ublisahneddw ithoau sti milar
conditiinocnl udtihnicgso nditbieoinn igm poseodnt hes ubsequpeunrtc haser.
Dedicated to the memory of Karl Popper, Hugh Everett and
Alan Turing, and to Richard Dawkins. This book takes their
ideas seriously.

Contents
Preface ix
Acknowledgements x
1 The Theory of Everything 1
Shadows 32.
2.
3 Problem-solving 55
Criteria for Reality 73
4
5 Virtual Reality 98
6 Universality and the Limits of Computation 1z.3
7 A Conversation About Justification 141
8 The Significance of Life 167
9 Quantum Computers 194
10 The Nature of Mathematics
2.2.2.
11 Time: The First Quantum Concept z.58
12. Time Travel z.89
13 The Four Strands 3z.1
14 The Ends of the Universe 344
Bibliography 367
Index 371

Preface
If there is a single motivation for the world-view set out in this
book, it is that thanks largely to a succession of extraordinary
scientific discoveries, we now possess some extremely deep theories
about the structure of reality. If we are to understand the world
on more than a superficial level, it must be through those theories
and through reason, and not through our preconceptions, received
opinion or even common sense. Our best theories are not only truer
than common sense, they make far more sense than common sense
does. We must take them seriously, not merely as pragmatic founda­
tions for their respective fields but as explanations of the world. And
I believe that we can achieve the greatest understanding if we consider
them not singly but jointly, for they are inextricably related.
It may seem odd that this suggestion -that we should try to form
a rational and coherent world-view on the basis of our best, most
fundamental theories -should be at all novel or controversial. Yet
in practice it is. One reason is that each of these theories has, when it
is taken seriously, very counter-intuitive implications. Consequently,
all sorts of attempts have been made to avoid facing those implica­
tions, by making ad hoc modifications or reinterpretations of the
theories, or by arbitrarily narrowing their domain of applicability,
or simply by using them in practice but drawing no wider conclusions
from them. I shall criticize some of these attempts (none of which,
I
believe, has much merit), but only when this happens to be a con­
venient way of explaining the theories themselves. For this book is
not primarily a defence of these theories: it is an investigation of what
the fabric of reality would be like if they were true.
IX