Table Of ContentNew Theories of Everything
also by john d. barrow
TheLeftHandofCreation(withJosephSilk)
L’HommeetleCosmos(withFrankJ.Tipler)
TheAnthropicCosmologicalPrinciple(withFrankJ.Tipler)
TheWorldWithintheWorld
TheArtfulUniverse
PiintheSky
Perchèilmondoèmatematico?
Impossibility
TheOriginoftheUniverse
BetweenInnerSpaceandOuterSpace
TheUniversethatDiscoveredItself
TheBookofNothing
TheConstantsofNature:FromAlphatoOmega
TheInfiniteBook
TheArtfulUniverseExpanded
john d barrow
.
New Theories
of Everything
the quest for ultimate explanation
‘Iamveryinterestedin
theUniverse—Iamspecialising
intheUniverseandall
thatsurroundsit’
—peter cook
1
3
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to roger
Whostillbelievesthereshouldalwaysbe
somethingratherthannothing
Preface to the Second Edition
I was pleased to take the opportunity, provided by the Press, to prepare
a new edition of Theories of Everything. Interest in this subject has con-
tinuedunabatedsincemyfirstattemptstoexplaintheirscopeandlimitations,
and to place them in a broader cultural context than that of mathematical
physics. Many new possibilities have emerged in the pursuit of a final string
theory,andcosmologyhastakenanunexpectedpathintoarealmpopulated
by many other possible universes. Both developments have undermined the
naïve expectations of many, that a Theory of Everythngwould uniquely and
completely specify all the defining quantities of the Universe that make it a
possiblehomeforlife.Thereisalongwaytogobeforethephysicists’Theory
ofEverythingisformulatedanddecisivelytested.Inthemeantime,Ihopethat
thisextendedsurveyofthenewestdevelopmentswillhelppointreadersinthe
rightdirectionandilluminatetheway.
JohnD.Barrow
Cambridge,February2007
Preface to the First Edition
‘Everything’isabigsubject.Yetmodernscientistsbelievetheyhavestumbled
uponakeywhichunlocksthemathematicalsecretattheheartoftheUniverse:
a discovery that points them towards a monumental ‘Theory of Everything’
whichwilluniteallthelawsofNatureintoasinglestatementthatrevealsthe
inevitability of everything that was, is, and is to come in the physical world.
Suchdreamsarenotnew;Einsteinwastedthelatterpartofhislifeinafruitless
andisolatedquestforjustthisTheoryofEverything.Buttodaysuchschemes
arenottobefoundonlyonthedesksofafewmaverickthinkersanduncon-
strainedspeculators;theyhaveenteredthemainstreamoftheoreticalphysics
andareworkeduponbyagrowingpopulationoftheworld’sbrightestyoung
thinkers.Thisturnofeventsraisesmanydeepquestions.Cantheirquestreally
succeed? Can our understanding of the logic underlying physical reality be
completed? Do we forsee a day when fundamental physics will be complete,
leavingonlythecomplexdetailslatentwithinthoselawstobeunravelled?Is
thistrulythenewfrontierofabstractthought?
This book is an attempt to describe what the challenge facing Theories of
Everythingreallyis;topickoutthoseaspectsofthingswhichmustbeunder-
stoodbeforewecanhaveanyrighttoclaimthatweunderstandthem.Weshall
try to show that while Theories of Everything, as currently conceived, may
wellprovenecessaryifwearetounderstandtheUniversearoundandwithin
us, they are far from sufficient. We shall introduce the reader to those extra
ingredientswhichweneedtocompleteourunderstandingofwhatis,andin
sodoingweaimtodisplaymanynewideasandspeculationswhichtranscend
traditionalthinkingaboutthescopeandstructureofscientificinquiry.
Numerouspeoplehavehelpedthisbookcometocompletion.TheSenatus
of the University of Glasgow invited the author to deliver a series of Gifford
Lectures at the University of Glasgow in January of 1988 and this book elab-
oratesuponthecontentofsomeofthoselectures.Iamparticularlyindebted
to Neil Spurway for his gracious help with everything associated with those
lectures.Foradvertentorinadvertentcommentsanddiscussionswhichhave
helped in the writing of this book I am grateful to David Bailin, Margaret
Boden, Danko Bosanac, Gregory Chaitin, Paul Davies, Bernard d’Espagnat,
viii preface to the first edition
Jeffrey Friedman, Michael Green, Chris Isham, John Manger, Bill McCrea,
Leon Mestel, John Polkinghorne, Aaron Sloman, John Maynard Smith, Neil
Spurway, Euan Squires, René Thom, Frank Tipler, John Wheeler, Denys
Wilkinson,PeterWilliams,andTomWillmore.
Writing a book can be a miserable business, not only for the author, but
forallthoseinhisimmediateorbit.Themostperceptivereflectionuponthis
situation was one made by the late Sir Peter Medawar. It applies not only to
theactivitiesofauthors,buttoobsessivesofmanysorts:‘... itisaproceeding
thatmakesoneratherinhuman,selfishlyguardingeverysecondofone’stime
andbecominginattentiveaboutpersonalrelationships;onesoonformedthe
opinionthatanyonewhousedthreewordswheretwowouldhavedonewasa
boreofinsufferableprolixitywhosecompanymustatalltimesbeshunned.A
dangersignthatfellow-obsessionalswillatoncerecognizeisthetendencyto
regardthehappiestmomentsofyourlifeas thosethatoccurwhensomeone
whohasanappointmenttoseeyouispreventedfromcoming.’Becauseofthe
danger of such distortions, family members require special thanks for their
patience and forbearance in the face of frequent neglect. Elizabeth has sup-
pliedherconstantsupportininnumerableways;withoutitthisworkwould
neverhavebegun.Finally,ourchildren,David,Roger,andLouise,haveshown
akeenandunnervinginterestintheprogressofthemanuscriptwithoutwhich
thebookwouldundoubtedlyhavebeenfinishedinhalfthetime.
J.D.B.
Brighton,September1990
acknowledgements
Figure 7.3 is reprinted by permission of the publishers from Mind Children
by Hans Moravec, Cambridge, Mass.: Harvard University Press, Copyright
© 1988 by the President and Fellows of Harvard College. Figs 7.2 and 7.4 are
adaptedfromthesamesource.Figure7.6iscopyright©R.V.Solé,reproduced
bypermissionoftheartist.
Contents
1
Ultimateexplanation 1
Aneightfoldway 1
Myths 4
Creationmyths 8
Algorithmiccompressibility 10
2
Laws 14
Thelegacyoflaw 14
Thequestforunity 17
RogerBoscovich 19
Symmetries 22
Infinities—tobeornottobe? 26
Fromstringsto‘M’ 32
Aflightofrationalisticfancy 36
Goodbyetoallthat 43
3
Initialconditions 44
Attheedgeofthings 44
Axioms 45
MathematicalJujitsu 51
Initialconditionsandtimesymmetry 61
Timewithouttime 62
Cosmologicaltime 66
Theproblemoftime 76
Absolutespaceandtime 78
Howfarisfarenough? 83
Thequantummysteryoftime 85
Quantuminitialconditions 88
Thegreatdivide 90
4
Forcesandparticles 93
ThestuffoftheUniverse 93
Thecopy-catprinciple 95
Elementarity 100
