Foreword, by Chris Isham page xvii
         Preface xix
         Notation and conventions xxiii
         Introduction: Defining quantum gravity 1
         Why quantum gravity in the twenty-first century? 1
         The role of background independence 8
         Approaches to quantum gravity 11
         Motivation for canonical quantum general relativity 23
         Outline of the book 25
         I CLASSICAL FOUNDATIONS, INTERPRETATION AND THE
         CANONICAL QUANTISATION PROGRAMME
         1 Classical Hamiltonian formulation of General Relativity 39
         1.1 The ADM action 39
         1.2 Legendre transform and Dirac analysis of constraints 46
         1.3 Geometrical interpretation of the gauge transformations 50
         1.4 Relation between the four-dimensional diffeomorphism group and
         the transformations generated by the constraints 56
         1.5 Boundary conditions, gauge transformations and symmetries 60
         1.5.1 Boundary conditions 60
         1.5.2 Symmetries and gauge transformations 65
         2 The problem of time, locality and the interpretation of
         quantum mechanics 74
         2.1 The classical problem of time: Dirac observables 75
         2.2 Partial and complete observables for general constrained systems 81
         2.2.1 Partial and weak complete observables 82
         2.2.2 Poisson algebra of Dirac observables 85
         2.2.3 Evolving constants 89
         2.2.4 Reduced phase space quantisation of the algebra of Dirac
         observables and unitary implementation of the
         multi-fingered time evolution 90
         2.3 Recovery of locality in General Relativity 93
         2.4 Quantum problem of time: physical inner product and
         interpretation of quantum mechanics 95
         2.4.1 Physical inner product 95
         2.4.2 Interpretation of quantum mechanics 98
         3 The programme of canonical quantisation 107
         3.1 The programme 108
         4 The new canonical variables of Ashtekar for
         General Relativity 118
         4.1 Historical overview 118
         4.2 Derivation of Ashtekar’s variables 123
         4.2.1 Extension of the ADM phase space 123
         4.2.2 Canonical transformation on the extended phase space 126
         II FOUNDATIONS OF MODERN CANONICAL QUANTUM
         GENERAL RELATIVITY
         5 Introduction 141
         5.1 Outline and historical overview 141
         6 Step I: the holonomy–flux algebra P 157
         6.1 Motivation for the choice of P 157
         6.2 Definition of P: (1) Paths, connections, holonomies and
         cylindrical functions 162
         6.2.1 Semianalytic paths and holonomies 162
         6.2.2 A natural topology on the space of generalised connections 168
         6.2.3 Gauge invariance: distributional gauge transformations 175
         6.2.4 The C∗ algebraic viewpoint and cylindrical functions 183
         6.3 Definition of P: (2) surfaces, electric fields, fluxes and vector fields 191
         6.4 Definition of P: (3) regularisation of the holonomy–flux
         Poisson algebra 194
         6.5 Definition of P: (4) Lie algebra of cylindrical functions and
         flux vector fields 202
         7 Step II: quantum ∗-algebra A 206
         7.1 Definition of A 206
         7.2 (Generalised) bundle automorphisms of A 209
         8 Step III: representation theory of A 212
         8.1 General considerations 212
         8.2 Uniqueness proof: (1) existence 219
         8.2.1 Regular Borel measures on the projective limit:
         the uniform measure 220
         8.2.2 Functional calculus on a projective limit 226
         8.2.3 + Density and support properties of A,A/G with respect
         to A,A/G 233
         8.2.4 Spin-network functions and loop representation 237
         8.2.5 Gauge and diffeomorphism invariance of μ0 242
         8.2.6 + Ergodicity of μ0 with respect to spatial diffeomorphisms 245
         8.2.7 Essential self-adjointness of electric flux momentum
         operators 246
         8.3 Uniqueness proof: (2) uniqueness 247
         8.4 Uniqueness proof: (3) irreducibility 252
         9 Step IV: (1) implementation and solution of the
         kinematical constraints 264
         9.1 Implementation of the Gauß constraint 264
         9.1.1 Derivation of the Gauß constraint operator 264
         9.1.2 Complete solution of the Gauß constraint 266
         9.2 Implementation of the spatial diffeomorphism constraint 269
         9.2.1 Derivation of the spatial diffeomorphism constraint
         operator 269
         9.2.2 General solution of the spatial diffeomorphism constraint 271
         10 Step IV: (2) implementation and solution of the
         Hamiltonian constraint 279
         10.1 Outline of the construction 279
         10.2 Heuristic explanation for UV finiteness due to background
         independence 282
         10.3 Derivation of the Hamiltonian constraint operator 286
         10.4 Mathematical definition of the Hamiltonian constraint operator 291
         10.4.1 Concrete implementation 291
         10.4.2 Operator limits 296
         10.4.3 Commutator algebra 300
         10.4.4 The quantum Dirac algebra 309
         10.5 The kernel of the Wheeler–DeWitt constraint operator 311
         10.6 The Master Constraint Programme 317
         10.6.1 Motivation for the Master Constraint Programme in
         General Relativity 317
         10.6.2 Definition of the Master Constraint 320
         10.6.3 Physical inner product and Dirac observables 326
         10.6.4 Extended Master Constraint 329
         10.6.5 Algebraic Quantum Gravity (AQG) 331
         10.7 + Further related results 334
         10.7.1 The Wick transform 334
         10.7.2 Testing the new regularisation technique by models of
         quantum gravity 340
         10.7.3 Quantum Poincar´e algebra 341
         10.7.4 Vasiliev invariants and discrete quantum gravity 344
         11 Step V: semiclassical analysis 345
         11.1 + Weaves 349
         11.2 Coherent states 353
         11.2.1 Semiclassical states and coherent states 354
         11.2.2 Construction principle: the complexifier method 356
         11.2.3 Complexifier coherent states for diffeomorphism-invariant
         theories of connections 362
         11.2.4 Concrete example of complexifier 367
         11.2.5 Semiclassical limit of loop quantum gravity: graph-changing
         operators, shadows and diffeomorphism-invariant
         coherent states 376
         11.2.6 + The infinite tensor product extension 385
         11.3 Graviton and photon Fock states from L2(A, dμ0) 390
         III PHYSICAL APPLICATIONS
         12 Extension to standard matter 399
         12.1 The classical standard model coupled to gravity 400
         12.1.1 Fermionic and Einstein contribution 401
         12.1.2 Yang–Mills and Higgs contribution 405
         12.2 Kinematical Hilbert spaces for diffeomorphism-invariant theories
         of fermion and Higgs fields 406
         12.2.1 Fermionic sector 406
         12.2.2 Higgs sector 411
         12.2.3 Gauge and diffeomorphism-invariant subspace 417
         12.3 Quantisation of matter Hamiltonian constraints 418
         12.3.1 Quantisation of Einstein–Yang–Mills theory 419
         12.3.2 Fermionic sector 422
         12.3.3 Higgs sector 425
         12.3.4 A general quantisation scheme 429
         13 Kinematical geometrical operators 431
         13.1 Derivation of the area operator 432
         13.2 Properties of the area operator 434
         13.3 Derivation of the volume operator 438
         13.4 Properties of the volume operator 447
         13.4.1 Cylindrical consistency 447
         13.4.2 Symmetry, positivity and self-adjointness 448
         13.4.3 Discreteness and anomaly-freeness 448
         13.4.4 Matrix elements 449
         13.5 Uniqueness of the volume operator, consistency with the flux
         operator and pseudo-two-forms 453
         13.6 Spatially diffeomorphism-invariant volume operator 455
         14 Spin foam models 458
         14.1 Heuristic motivation from the canonical framework 458
         14.2 Spin foam models from BF theory 462
         14.3 The Barrett–Crane model 466
         14.3.1 Plebanski action and simplicity constraints 466
         14.3.2 Discretisation theory 472
         14.3.3 Discretisation and quantisation of BF theory 476
         14.3.4 Imposing the simplicity constraints 482
         14.3.5 Summary of the status of the Barrett–Crane model 494
         14.4 Triangulation dependence and group field theory 495
         14.5 Discussion 502
         15 Quantum black hole physics 511
         15.1 Classical preparations 514
         15.1.1 Null geodesic congruences 514
         15.1.2 Event horizons, trapped surfaces and apparent horizons 517
         15.1.3 Trapping, dynamical, non-expanding and (weakly) isolated
         horizons 519
         15.1.4 Spherically symmetric isolated horizons 526
         15.1.5 Boundary symplectic structure for SSIHs 535
         15.2 Quantisation of the surface degrees of freedom 540
         15.2.1 Quantum U(1) Chern–Simons theory with punctures 541
         15.3 Implementing the quantum boundary condition 546
         15.4 Implementation of the quantum constraints 548
         15.4.1 Remaining U(1) gauge transformations 549
         15.4.2 Remaining surface diffeomorphism transformations 550
         15.4.3 Final physical Hilbert space 550
         15.5 Entropy counting 550
         15.6 Discussion 557
         16 Applications to particle physics and quantum cosmology 562
         16.1 Quantum gauge fixing 562
         16.2 Loop Quantum Cosmology 563
         17 Loop Quantum Gravity phenomenology 572
         IV MATHEMATICAL TOOLS AND THEIR CONNECTION
         TO PHYSICS
         18 Tools from general topology 577
         18.1 Generalities 577
         18.2 Specific results 581
         19 Differential, Riemannian, symplectic and complex
         geometry 585
         19.1 Differential geometry 585
         19.1.1 Manifolds 585
         19.1.2 Passive and active diffeomorphisms 587
         19.1.3 Differential calculus 590
         19.2 Riemannian geometry 606
         19.3 Symplectic manifolds 614
         19.3.1 Symplectic geometry 614
         19.3.2 Symplectic reduction 616
         19.3.3 Symplectic group actions 621
         19.4 Complex, Hermitian and K¨ahler manifolds 623
         20 Semianalytic category 627
         20.1 Semianalytic structures on Rn 627
         20.2 Semianalytic manifolds and submanifolds 631
         21 Elements of fibre bundle theory 634
         21.1 General fibre bundles and principal fibre bundles 634
         21.2 Connections on principal fibre bundles 636
         22 Holonomies on non-trivial fibre bundles 644
         22.1 The groupoid of equivariant maps 644
         22.2 Holonomies and transition functions 647
         23 Geometric quantisation 652
         23.1 Prequantisation 652
         23.2 Polarisation 662
         23.3 Quantisation 668
         24 The Dirac algorithm for field theories with constraints 671
         24.1 The Dirac algorithm 671
         24.2 First- and second-class constraints and the Dirac bracket 674
         25 Tools from measure theory 680
         25.1 Generalities and the Riesz–Markov theorem 680
         25.2 Measure theory and ergodicity 687
         26 Key results from functional analysis 689
         26.1 Metric spaces and normed spaces 689
         26.2 Hilbert spaces 691
         26.3 Banach spaces 693
         26.4 Topological spaces 694
         26.5 Locally convex spaces 694
         26.6 Bounded operators 695
         26.7 Unbounded operators 697
         26.8 Quadratic forms 699
         27 Elementary introduction to Gel’fand theory for
         Abelian C∗-algebras 701
         27.1 Banach algebras and their spectra 701
         27.2 The Gel’fand transform and the Gel’fand isomorphism 709
         28 Bohr compactification of the real line 713
         28.1 Definition and properties 713
         28.2 Analogy with loop quantum gravity 715
         29 Operator ∗-algebras and spectral theorem 719
         29.1 Operator ∗-algebras, representations and GNS construction 719
         29.2 Spectral theorem, spectral measures, projection valued measures,
         functional calculus 723
         30 Refined algebraic quantisation (RAQ) and direct integral
         decomposition (DID) 729
         30.1 RAQ 729
         30.2 Master Constraint Programme (MCP) and DID 735
         31 Basics of harmonic analysis on compact Lie groups 746
         31.1 Representations and Haar measures 746
         31.2 The Peter and Weyl theorem 752
         32 Spin-network functions for SU(2) 755
         32.1 Basics of the representation theory of SU(2) 755
         32.2 Spin-network functions and recoupling theory 757
         32.3 Action of holonomy operators on spin-network functions 762
         32.4 Examples of coherent state calculations 765
         33 + Functional analytic description of classical connection
         dynamics 770
         33.1 Infinite-dimensional (symplectic) manifolds 770
         References 775
         Index 809
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