The Pursuit of Quantum Gravity: Memoirs of Bryce DeWitt from 1946 to 2004

160 Pages·2011·3.618 MB·English

by  Cécile DeWitt-Morette (auth.)

The Pursuit of Quantum Gravity

Cécile DeWitt-Morette
The Pursuit of Quantum
Gravity
Memoirs of Bryce DeWitt from 1946 to 2004
123
CécileDeWitt-Morette
DepartmentofPhysics
CenterforRelativity
UniversityofTexasatAustin
AustinTexas
USA
[email protected]
ISBN978-3-642-14269-7 e-ISBN978-3-642-14270-3
DOI10.1007/978-3-642-14270-3
SpringerHeidelbergDordrechtLondonNewYork
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Dedicatedtoourdaughters, Nicolette,Jan,
Christiane,Abigail

Preface
Thisbookiswrittenforthecuriousreader.Ihopeitwillalsobeagoodread
fortheprofessionalphysicist.Itdevelopsandsupplementsthebiographical
memoir(16pages)preparedbyStevenWeinbergfortheNationalAcademy
of Sciences.1 It is also a companion to Bryce DeWitt’s last book [BD 103]2
The Global Approach toQuantum Field Theory (1042pages, firstpublished
in 2003, reprinted with corrections in 2004). Bryce’s book is an excellent
physicist’srecordofhispursuitofquantumgravity.
As an introduction to the theme of the book, two pieces from Bryce
DeWittarereproducedinextenso:
(cid:2) “Why Physics?” consists of a few hand-written pages addressed to his
grandson,and
(cid:2) Aposthumouslypublishedarticle“QuantumGravity:YesterdayandTo-
day”addressingthequestions:“WhyQuantumGravity?”and“WhyLink
QuantumGravityandBryceDeWitt’sMemoirs?”
Thestructuresofquantumphysicsandgravitationphysicsdonotconstitute
a single logical system. Digging deeper into their respective structures may
revealacommonroot.Thereforethepursuitofquantumgravityrequiresa
profoundunderstandingof both quantumphysicsandgravitation physics.
AsG.A.Vilkoviskywrotetome,“QuantumGravityisacombinationoftwo
words, and one should know both. Bryce understood this as nobody else,
andthiswisdomiscompletelyunknowntomanyauthorsofthefluxofpa-
persthatweseenowadays.”3
SectionsIandIIdealwiththestatusofquantumphysicsandgravitation
physicsinthelateforties.Acoupleofmajortopicsarethenselectedineach
1 Steven Weinberg, “Bryce Seligman DeWitt, 1923–2004: A Biographical Memoir”,
National Academy of Sciences (2008). This memoir incorporates materials given to
WeinbergbyDeWittbeforehisdeathandisreproducedinSect.V.1.
2ReferencestoDeWitt’sownlistofpublicationsareindicatedinthetextinsquarebrack-
etsprependedBD.
3E-mailcorrespondencedatedDec.28,2007.
vii
fieldbecausetheywereofspecialinteresttoBryce.Quantumgravityitselfis
thefocusofSect.III.ItcapturesBryce’sworkfrom1946to2004andplaces
itinitsscientific,historical,andhumancontext.
I have been blessed and burdened by an enormous amount of mate-
rial for the preparation of this book; in addition to, I believe, a complete
set ofpublished material,Ihavemost ofBryce’sreportstoinstitutions and
refereereportstojournals,lettersofrecommendation,correspondence,re-
searchproposals,unpublished documents, andmymemories(lessouvenirs
quelamémoireinvente!4).
IhaveincludedextensivequotesfromBryce.Theyareprintedinblue.
Bryce’s writings were carefully crafted, and he could not stand any editing
(except by his fourth daughter Abigail, who edited his last writing “God’s
Rays”). Therefore I could not summarize his quotes, paraphrase them, or
select briefquotesoutofcontext. Ihaveaddedintroductions, motivations,
andhistoricalcommentsthatplacehistechnicalprogressinalargercontext
andmake his research paperseasier to read.5 I haveincluded a few techni-
cal notes when necessary to justify some statements. The reader not inter-
ested in technical details can gloss over them without losing the thread of
the topic. The material in blue (Bryce’s quotes) and the material in black
(Cécile’scontributionsandothers’)aremeaningfulbythemselves;together
they make a whole. Including extensive quotes occasionally creates a few
duplications,buttheyarenotverbatimduplications;alaterquoteshowsthe
maturationofanearlierone.
MytaskhasbeenmademanageablethankstothehelpofBrandonDiN-
unno, John Stachel, andLawrence Shepley, andtotheofferfromThe Uni-
versityofTexasCenterforAmericanHistorytobetherepositoryofBryce’s
documents.6
ThesupportthatTheUniversityofTexasprovidestoitsProfessorsEmer-
itiisgratefullyacknowledged.Withoutanoffice,andallthefacilitiesofthe
PhysicsDepartment,I couldnothavecompleted thistask in atimely fash-
ion.Inaddition,myofficeisclosetoAustinGleeson’sandwheneverIneeded
something,Ionlyhadtopokemyheadinhisalwaysopendoor.
Ihaveenjoyedmanyvisits totheInstitutdesHautesEtudes Scientifiques
at Bures-sur-Yvette, France, an oasis in the fast moving, crowded schedule
ofmoderntimes–anoasiswhereonefindsthepeacenecessaryforconcen-
trationandthestimulationofothertravellersfollowingtheirownpursuits.
4Recollectionsthatmemoryinvents.
5Forinstance,inBryce’scondensednotation,anindexmayrefertocoordinatesbothin
thedomainandintherangeofthefunction.Occasionallyheusedmathematicalterms
heuristically;Ihaveoftenbeenfrustratedbyhisuseoftheword“measure”infunctional
integrals.Likemanyphysicistshetalksofgaugefieldsasconnections.Inrealitygauge
potentialsarepull-backsofconnectionsonaprincipalbundle.
6seeSect.V.4.
viii
Thesepagesarememoirsaroundthetheme“QuantumGravity”.7 Once
aneglectedprobleminthebackwatersoftheflowofphysicsresearch,quan-
tumgravityhasnowbecomeamajorchallengeinfundamentalphysics.8
Thepursuitofquantumgravitygoeson.Thisbookbeganasascrapbook
of its beginnings and matured into its present form, though it is not, and
wasnotmeanttobe,ascholarlypieceofScienceHistoryinthestrictsense.
Some colleagues havesuggested pertinent additions, in particularThibault
Damour,JürgFröhlich,PhillipMorrison,andLarrySmarr,butIhavekept
in mind the size of the book and its scientific level – and hope to have
achievedanicelyreadablebalance.
Therearesomewhoseemtoquestiontherôleofpublishersintheageof
the internet; but a great publisher eliminates the gangue from the mineral
orebyadditionorbysubtraction.Mymanuscripthasbeenmadeintoabook
thankstothecareandexpertiseofDr.ChristianCaron,ExecutivePublishing
Editor at Springer-Verlag, Theodor C.H. Cole, Copy and Language Editor,
andBirgitMünch,DeskEditor.
CécileMorette,épouseDeWitt9
7Forabalancednon-technicalreviewonthedevelopmentofthefieldasawhole,seee.g.
C.Rovelli,Notesforabriefhistoryofquantumgravity,arXiv:gr-qc/0006061v3(23Jan
2001).
8 It is also mentioned outsidephysics. For instance, when Alan Sokal wanted to play
ahoax onaculturalstudiesjournal,hesentaparodyofpostmodernacademic prose
titled“TransgressingtheBoundariesTowardsaTransformativeHermeneuticsofQuan-
tumGravity”toSocialText.Thearticlewaspublishedin1996,andthehoaxbecamean
often-quotedanecdote(AlanD.Sokal,“TransgressingtheBoundariesTowardsaTrans-
formativeHermeneuticsofQuantumGravity”,SocialText46/47,217–252(1996)).
9 IusemyFrenchlegal name to indicate that mywork as aphysicistand as a spouse
areindependentofeachother.Theconceptofaperson,oranobject,assumingdifferent
functions in different contexts is not unusual. In mathematics an operator is defined
onlytogetherwiththespaceonwhichitoperates.Thesameistrueinhumanrelation-
ships.Asamotherandasawifeaperson’sbehaviormaybedifferent.Thelabel“spouse”
was inappropriatelyattached to my qualifications as physicist, and antinepotism reg-
ulationswere invokedtodenymeapositioninthesamedepartmentasmyhusband.
Theconcept“conflictofinterest”issometimesusedinappropriately.MyFrenchname,
as recorded on my birth certificate is “Cécile, Andrée, Paulette Morette-Payen, veuve
DeWitt”Iprefer“épouse”to“veuve”.Frenchbirthcertificatesareupdatedtoreflectan
individual’sÉtatCivil.
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