Chance in Physics Foundations and Perspectives

TheconferenceChanceinPhysics:FoundationsandPerspectiveswasheldfrom 29thNovemberto3rdDecember1999inIschia,Italy. Itwassponsoredbythe IstitutoItalianoPerGliStudiFiloso?ciinNaples,bytheDeutscheForschun- gemeinschaft(DFG),andbytheSociet`aItalianaDiFondamentiDellaFisica. SponsoringbytheInternationalSchoolforAdvancedStudies(ISAS)ofTrieste, Italy,madethecompilationofthisvolumepossible;thefundingbytheIs- tutoItalianoPerGliStudiFiloso?ciwascrucialfortheconferenceandisvery gratefullyacknowledged. TheIstitutomanagedtoprovideauniqueatmosphere foraninterdisciplinarymeeting,andtheseproceedingsre?ectindeedthevery friendlybutneverthelessintenseandneverendingdiscussionsononeofthemost debatedissuesofscience:probability,andinparticularprobabilityinphysics. Wegratefullyacknowlegdetheorganisationalworkaswellastheeditorialwork donebyoursecretaryofthemeetingPhDstudentRoderichTumulka. Themeetingwasintendedtostimulaterenewedre?ectiononthefundam- talandpracticalaspectsofprobabilityinphysics,inparticularthefoundations ofstatisticalsechanics,theprobabilityinthefoundationsofquantummech- ics,thealgebraicviewofprobabilityandthephilosophyofprobabilityinits interrelationwithphysics. Questionslikewhatprobabilityis,orwhatitisabout,orhowprobability entersphysicsareofasubtlekind. Theyaredi?cultinvariousways,often mixedupwiththeenormouscomplexityandtheinescapablelackofmat- maticalrigorinthephysicalapplication,orwiththefoundationalproblemsof quantummechanics,wheretheprobabilisticignoranceconcerningthevaluesof certainphysicalquantitieshasevenbeenelevatedtoamatterofprinciple. At present,theunderstandingofprobabilityinphysicsisalmostaspersonalasthe understandingofquantumtheory. Theaimoftheconferencewasthustofocusonideasaboutprobabilityin physics,itsmeaninganditsphilosophicalimplications,byreviewingthedi?erent facetsofprobabilityinphysicsinitsmodernsettingsandbytakingintoaccount modernquantumtheorieswithoutobservers,wheretheoriginofprobabilityis notmysti?edbydogmatism. Thereviewsweregiveninone-hourtalks,andthediscussionswereheldin theformofroundtables,whereshortercontributionswerealsogiven. Thespeakerswereaskednottodilutethemainthemesoftheconference withtechnicalitiesandtofocussharplyontheissueofprobability. Thiswas VI Preface takentoheartbyallspeakersandthemeetingthusprovedverysuccessful. The contributionsinthisvolumeconsequentlyfocusonconceptualissues,andthey makeworthwhilereadingforspecialistsinthe?eldoffoundationsaswellasfor nonspecialists,becauseextensivetechnicalpriorknowledgeisnotrequired. The contributionshavebeenleftintheordertheywerediscussedinthemeeting, whichprovedtobeaverynaturalone: 1. ClassicalStatisticalMechanics,whereBoltzmann’sunderstandingofstat- ticalmechnanicsasarisingfromkineticgastheoryisreviewedandputinto modernperspectives,withanoutlookonrelativisticstatisticalmechanics. Therelativelackofemphasisonthee?ectofchaoticbehaviouronthefo- dationsofprobabilityisnoteworthy. 2. QuantumMechanics,wherewereviewthoseontologicalquantumtheories, thathavebeenmostseriouslydiscussedintherecentyears. Amongthese areadeterministictheory(Bohmianmechanics)andboththeintrinsically randomtheoriesofwavepacketreductionandtheoperator-basedconsistent (decoherent)histories. Itstartswiththe“orthodox”view,againwith- phasisontheprobabilisticaspectsofthesetheories. 3. Chaoticsystems,wherethedynamicalaspectsforthefoundationsofpro- bilityinphysicsareadressed. 4. PhilosophyofProbability,wheretheissuesoftheearliersectionsarefurther scrutinizedonphilosophicalgrounds. Thesecontributionshavenoabstracts. Thebookstartswithanintroductorypaper,inwhichalmostallthetopics whicharediscussedbythelatercontributionsarecriticallypresented. M ̈unchen, J. Bricmont,D. Durr, ̈ M. C. Galavotti, January2001 G. C. Ghirardi,F. Petruccione,N. Zangh`? TableofContents PartI Introduction Bayes,BoltzmannandBohm:ProbabilitiesinPhysics JeanBricmont. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 PartII ClassicalStatisticalMechanics TheRiseofStatisticalMechanics CarloCercignani. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Boltzmann’sApproachtoStatisticalMechanics SheldonGoldstein. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 MicroscopicTimeReversibilityandtheBoltzmannEquation HerbertSpohn. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 TheDirectionofTime OliverPenrose. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 HowtoImplementBoltzmann’sProbabilisticIdeas inaRelativisticWorld? MichaelK. -H. Kiessling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 PartIII QuantumMechanics ProbabilityinOrthodoxQuantumMechanics: ProbabilityasaPostulate VersusProbabilityasanEmergentPhenomenon StephenL. Adler. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 BohmianMechanics DetlefDurr ̈ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115 ChanceofReductionasChanceofSpontaneousLocalisation AlbertoRimini. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 VIII TableofContents Probabilities,DecoheringHistories, andtheInterpretationofQuantumMechanics RolandOmn`es. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149 SpaceTimeandProbability SimonW. Saunders. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157 HiddenVariables,StatisticalMechanicsandtheEarlyUniverse AntonyValentini. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165 PerspectivesoftheDynamicalReductionProgram GianCarloGhirardi. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183 RelativisticTheoryofContinuousMeasurements Heinz–PeterBreuer,FrancescoPetruccione. . . . . . . . . . . . . . . . . . . . . . . . . . . 195 ProbabilisticResultsforSixDetectors inaThree-ParticleGHZExperiment Jos ́eAcaciodeBarros,PatrickSuppes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213 ClassicalVersusQuantumProbabilities EnricoG. Beltrametti. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225 PartIV ChaoticSystems DoesQuantumChaosExist? AndreasKnauf. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235 Time-ScalesfortheApproachtoThermalEquilibrium StefanoRu?o. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243 Einstein’sNonconventionalConceptionofthePhoton andtheModernTheoryofDynamicalSystems AndreaCarati,LuigiGalgani. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253 PartV PhilosophyofProbability WhatInterpretationforProbabilityinPhysics? MariaCarlaGalavotti. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265 StatisticalMechanics andthePropensityInterpretationofProbability PeterJ. Clark. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271 InterpretingProbabilities: What’sInterferenceGottoDowithIt? TimMaudlin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283 ListofParticipants Adami,Riccardo,Roma,Italy Booss-Bavnbek,Bernhelm,Roskilde, adami@mat. uniroma1. it Denmark booss@mmf. ruc. dk Adams,Stefan,Munc ̈ hen,Germany adams@rz. mathematik. Breuer,Heinz-Peter,Freiburg,Germany uni-muenchen. de breuer@physik. uni-freiburg. de Adler,Stephen,IASPrinceton,USA Bricmont,Jean,Louvain-la-Neuve, adler@sns. ias. edu Belgium bricmont@fyma. ucl. ac. be Agnese,Angelo,Genova,Italy agnese@ge. infn. it Butter?eld,JeremyN. ,Cambridge,UK jb56@cus. cam. ac. uk Albert,DavidZ. ,NewYork,USA da5@columbia. edu Casati,Giulio,Como,Italy casati@fis. unico. it Allori,Valia,Genova,Italy, allori@mi. infn. it Castellani,Elena,Firenze,Italy castella@philos. unifi. it Arntzenius,Frank,NewBrunswick,USA arntzeni@rci. rutgers.