Approaches to Quantum Gravity: Toward a New Understanding of Space, Time and Matter

605 Pages·2009·4.903 MB·English

by  Daniele Oriti

Approaches to
Quantum Gravity
By
Daniele Oriti
This page intentionally left blank
APPROACHES TO QUANTUM GRAVITY
TowardaNewUnderstandingofSpace,TimeandMatter
The theory of quantum gravity promises a revolutionary new understanding
of gravity and spacetime, valid from microscopic to cosmological distances.
Researchinthisfieldinvolvesanexcitingblendofrigorousmathematicsandbold
speculations,foundationalquestionsandtechnicalissues.
Containing contributions from leading researchers in this field, this book
presentsthefundamentalissuesinvolvedintheconstructionofaquantumtheoryof
gravityandbuildingupaquantumpictureofspaceandtime.Itintroducesthemost
current approaches to this problem, and reviews their main achievements. Each
part ends in questions and answers, in which the contributors explore the merits
andproblemsofthevariousapproaches.Thisbookprovidesacompleteoverview
ofthisfieldfromthefrontiersoftheoreticalphysicsresearchforgraduatestudents
andresearchers.
DANIELE ORITI is a Researcher at the Max Planck Institute for Gravitational
Physics, Potsdam, Germany, working on non-perturbative quantum gravity. He
has previously worked at the Perimeter Institute for Theoretical Physics, Canada;
the Institute for Theoretical Physics at Utrecht University, The Netherlands; and
the Department of Applied Mathematics and Theoretical Physics, University of
Cambridge, UK. He is well known for his results on spin foam models, and is
among the leading researchers in the group field theory approach to quantum
gravity.

APPROACHES TO QUANTUM GRAVITY
Toward a New Understanding of Space,
Time and Matter
Editedby
DANIELE ORITI
MaxPlanckInstituteforGravitationalPhysics,
Potsdam,Germany
CAMBRIDGE UNIVERSITY PRESS
Cambridge, New York, Melbourne, Madrid, Cape Town, Singapore, São Paulo
Cambridge University Press
The Edinburgh Building, Cambridge CB2 8RU, UK
Published in the United States of America by Cambridge University Press, New York
www.cambridge.org
Information on this title: www.cambridge.org/9780521860451
© Cambridge University Press 2009
This publication is in copyright. Subject to statutory exception and to the
provision of relevant collective licensing agreements, no reproduction of any part
may take place without the written permission of Cambridge University Press.
First published in print format 2009
ISBN-13 978-0-511-51640-5 eBook (EBL)
ISBN-13 978-0-521-86045-1 hardback
Cambridge University Press has no responsibility for the persistence or accuracy
of urls for external or third-party internet websites referred to in this publication,
and does not guarantee that any content on such websites is, or will remain,
accurate or appropriate.
ASandra

Contents
Listofcontributors pagex
Preface xv
PartI Fundamentalideasandgeneralformalisms 1
1 Unfinishedrevolution 3
C.Rovelli
2 Thefundamentalnatureofspaceandtime 13
G.’tHooft
3 Doeslocalityfailatintermediatelengthscales? 26
R.D.Sorkin
4 ProlegomenatoanyfutureQuantumGravity 44
J.Stachel
5 Spacetimesymmetriesinhistoriescanonicalgravity 68
N.Savvidou
6 Categoricalgeometryandthemathematical
foundationsofQuantumGravity 84
L.Crane
7 Emergentrelativity 99
O.Dreyer
8 Asymptoticsafety 111
R.Percacci
9 NewdirectionsinbackgroundindependentQuantumGravity 129
F.Markopoulou
Questionsandanswers 150
PartII String/M-theory 167
10 Gauge/gravityduality 169
G.HorowitzandJ.Polchinski
vii
viii Contents
11 Stringtheory,holographyandQuantumGravity 187
T.Banks
12 Stringfieldtheory 210
W.Taylor
Questionsandanswers 229
PartIII Loopquantumgravityandspinfoammodels 233
13 Loopquantumgravity 235
T.Thiemann
14 Covariantloopquantumgravity? 253
E.Livine
15 Thespinfoamrepresentationofloopquantumgravity 272
A.Perez
16 Three-dimensionalspinfoamQuantumGravity 290
L.Freidel
17 ThegroupfieldtheoryapproachtoQuantumGravity 310
D.Oriti
Questionsandanswers 332
PartIV DiscreteQuantumGravity 339
18 QuantumGravity:theartofbuildingspacetime 341
J.Ambjørn,J.JurkiewiczandR.Loll
19 QuantumReggecalculus 360
R.Williams
20 ConsistentdiscretizationsasaroadtoQuantumGravity 378
R.GambiniandJ.Pullin
21 ThecausalsetapproachtoQuantumGravity 393
J.Henson
Questionsandanswers 414
PartV EffectivemodelsandQuantumGravityphenomenology 425
22 QuantumGravityphenomenology 427
G.Amelino-Camelia
23 QuantumGravityandprecisiontests 450
C.Burgess
24 AlgebraicapproachtoQuantumGravityII:noncommutative
spacetime 466
S.Majid