Modern Classical Physics Modern Classical Physics Optics, Fluids, Plasmas, Elasticity, Relativity, and Statistical Physics KIPS.THORNE and ROGERD.BLANDFORD PRINCETONUNIVERSITYPRESS PrincetonandOxford Copyright©2017byPrincetonUniversityPress PublishedbyPrincetonUniversityPress,41WilliamStreet,Princeton,NewJersey08540 IntheUnitedKingdom:PrincetonUniversityPress,6OxfordStreet,Woodstock,OxfordshireOX201TR press.princeton.edu AllRightsReserved LibraryofCongressCataloging-in-PublicationData Names:Thorne,KipS.,author.|Blandford,RogerD.,author. Title:Modernclassicalphysics:optics,fluids,plasmas,elasticity, relativity,andstatisticalphysics/KipS.ThorneandRogerD.Blandford. Description:Princeton:PrincetonUniversityPress,2017.|Includes bibliographicalreferencesandindex. Identifiers:LCCN2014028150|ISBN9780691159027(hardcover:alk.paper)| ISBN0691159025(hardcover:alk.paper) Subjects:LCSH:Physics. Classification:LCCQC21.3.T462015|DDC530—dc23 LCrecordavailableathttps://lccn.loc.gov/2014028150 BritishLibraryCataloging-in-PublicationDataisavailable ThisbookhasbeencomposedinMinionPro,Whitney,andRatioModernusingZzTEXbyWindfall Software,Carlisle,Massachusetts Printedonacid-freepaper. PrintedinChina 10 9 8 7 6 5 4 3 2 1 To Carolee and Liz CONTENTS ListofBoxes xxvii Preface xxxi Acknowledgments xxxix PARTI FOUNDATIONS 1 1 NewtonianPhysics:GeometricViewpoint 5 1.1 Introduction 5 1.1.1 TheGeometricViewpointontheLawsofPhysics 5 1.1.2 PurposesofThisChapter 7 1.1.3 OverviewofThisChapter 7 1.2 FoundationalConcepts 8 1.3 TensorAlgebrawithoutaCoordinateSystem 10 1.4 ParticleKineticsandLorentzForceinGeometricLanguage 13 1.5 ComponentRepresentationofTensorAlgebra 16 1.5.1 Slot-NamingIndexNotation 17 1.5.2 ParticleKineticsinIndexNotation 19 1.6 OrthogonalTransformationsofBases 20 1.7 DifferentiationofScalars,Vectors,andTensors;CrossProductandCurl 22 1.8 Volumes,Integration,andIntegralConservationLaws 26 1.8.1 Gauss’sandStokes’Theorems 27 1.9 TheStressTensorandMomentumConservation 29 1.9.1 Examples:ElectromagneticFieldandPerfectFluid 30 1.9.2 ConservationofMomentum 31 1.10 GeometrizedUnitsandRelativisticParticlesforNewtonianReaders 33 1.10.1 GeometrizedUnits 33 1.10.2 EnergyandMomentumofaMovingParticle 34 BibliographicNote 35 TrackTwo;seepagexxxiv Nonrelativistic(Newtonian)kinetictheory;seepage96 Relativistictheory;seepage96 vii 2 SpecialRelativity:GeometricViewpoint 37 2.1 Overview 37 2.2 FoundationalConcepts 38 2.2.1 InertialFrames,InertialCoordinates,Events,Vectors,andSpacetimeDiagrams 38 2.2.2 ThePrincipleofRelativityandConstancyofLightSpeed 42 2.2.3 TheIntervalandItsInvariance 45 2.3 TensorAlgebrawithoutaCoordinateSystem 48 2.4 ParticleKineticsandLorentzForcewithoutaReferenceFrame 49 2.4.1 RelativisticParticleKinetics:WorldLines,4-Velocity,4-Momentumand ItsConservation,4-Force 49 2.4.2 GeometricDerivationoftheLorentzForceLaw 52 2.5 ComponentRepresentationofTensorAlgebra 54 2.5.1 LorentzCoordinates 54 2.5.2 IndexGymnastics 54 2.5.3 Slot-NamingNotation 56 2.6 ParticleKineticsinIndexNotationandinaLorentzFrame 57 2.7 LorentzTransformations 63 2.8 SpacetimeDiagramsforBoosts 65 2.9 TimeTravel 67 2.9.1 MeasurementofTime;TwinsParadox 67 2.9.2 Wormholes 68 2.9.3 WormholeasTimeMachine 69 2.10 DirectionalDerivatives,Gradients,andtheLevi-CivitaTensor 70 2.11 NatureofElectricandMagneticFields;Maxwell’sEquations 71 2.12 Volumes,Integration,andConservationLaws 75 2.12.1 SpacetimeVolumesandIntegration 75 2.12.2 ConservationofChargeinSpacetime 78 2.12.3 ConservationofParticles,BaryonNumber,andRestMass 79 2.13 Stress-EnergyTensorandConservationof4-Momentum 82 2.13.1 Stress-EnergyTensor 82 2.13.2 4-MomentumConservation 84 2.13.3 Stress-EnergyTensorsforPerfectFluidsandElectromagneticFields 85 BibliographicNote 88 PARTII STATISTICALPHYSICS 91 3 KineticTheory 95 3.1 Overview 95 3.2 PhaseSpaceandDistributionFunction 97 3.2.1 NewtonianNumberDensityinPhaseSpace,N 97 3.2.2 RelativisticNumberDensityinPhaseSpace,N 99 viii Contents 3.2.3 DistributionFunctionf(x,v,t)forParticlesinaPlasma 105 3.2.4 DistributionFunctionI /ν3forPhotons 106 ν 3.2.5 MeanOccupationNumberη 108 3.3 Thermal-EquilibriumDistributionFunctions 111 3.4 MacroscopicPropertiesofMatterasIntegralsoverMomentumSpace 117 3.4.1 ParticleDensityn,FluxS,andStressTensorT 117 (cid:2) 3.4.2 RelativisticNumber-Flux4-VectorSandStress-EnergyTensorTTT 118 3.5 IsotropicDistributionFunctionsandEquationsofState 120 3.5.1 NewtonianDensity,Pressure,EnergyDensity,andEquationofState 120 3.5.2 EquationsofStateforaNonrelativisticHydrogenGas 122 3.5.3 RelativisticDensity,Pressure,EnergyDensity,andEquationofState 125 3.5.4 EquationofStateforaRelativisticDegenerateHydrogenGas 126 3.5.5 EquationofStateforRadiation 128 3.6 EvolutionoftheDistributionFunction:Liouville’sTheorem,theCollisionless BoltzmannEquation,andtheBoltzmannTransportEquation 132 3.7 TransportCoefficients 139 3.7.1 DiffusiveHeatConductioninsideaStar 142 3.7.2 Order-of-MagnitudeAnalysis 143 3.7.3 AnalysisUsingtheBoltzmannTransportEquation 144 BibliographicNote 153 4 StatisticalMechanics 155 4.1 Overview 155 4.2 Systems,Ensembles,andDistributionFunctions 157 4.2.1 Systems 157 4.2.2 Ensembles 160 4.2.3 DistributionFunction 161 4.3 Liouville’sTheoremandtheEvolutionoftheDistributionFunction 166 4.4 StatisticalEquilibrium 168 4.4.1 CanonicalEnsembleandDistribution 169 4.4.2 GeneralEquilibriumEnsembleandDistribution;GibbsEnsemble; GrandCanonicalEnsemble 172 4.4.3 Fermi-DiracandBose-EinsteinDistributions 174 4.4.4 EquipartitionTheoremforQuadratic,ClassicalDegreesofFreedom 177 4.5 TheMicrocanonicalEnsemble 178 4.6 TheErgodicHypothesis 180 4.7 EntropyandEvolutiontowardStatisticalEquilibrium 181 4.7.1 EntropyandtheSecondLawofThermodynamics 181 4.7.2 WhatCausestheEntropytoIncrease? 183 4.8 EntropyperParticle 191 4.9 Bose-EinsteinCondensate 193 Contents ix