The Emergent Multiverse: Quantum Theory according to the Everett Interpretation

547 Pages·2012·1.93 MB·English

by  David Wallace

The Emergent Multiverse
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The Emergent
Multiverse
Quantum Theory according to the
Everett Interpretation
David Wallace
1
3
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To Hannah
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Wehave,then,atheorywhichisobjectivelycausalandcontinuous,whileatthe
sametimesubjectivelyprobabilisticanddiscontinuous.Itcanlayclaimtoacertain
completeness,sinceitappliestoallsystems,ofwhateversize,andisstillcapableof
explainingtheappearenceofthemacroscopicworld.Theprice,however,isthe
abandonmentoftheconceptoftheuniquenessoftheobserver,withitssomewhat
disconcertingphilosophicalimplications.
(HughEverettIII,draftPh.D.thesis;cutfromsubmittedversionatJ.A.Wheeler’s
request)
What would it have looked like if it had looked like the Earth went round the
Sun?
(AttributedtoLudwigWittgenstein)
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Contents
ListofFiguresandBoxes xiv
Acknowledgements xvi
Introduction 1
Part I. The Plurality of Worlds
1. TheParadoxofMeasurement 11
1.1. Thegoalsofscience 11
1.2. Quantummechanics:thebareformalism 14
1.3. Quantummechanics:interpretationandmeasurement 16
1.4. ‘Measurement’cannotberepresentedphysically? 22
1.5. Themeasurementproblemandtheinstrumentalistresponse 24
1.6. Beyondinstrumentalism:vestigesofreality? 28
1.7. Solvingthemeasurementproblem:alternativetheories 31
1.8. Everett’sinsight 35
1.9. ThechallengesfortheEverettinterpretation 39
2. TheEmergenceofMultiplicity 46
2.1. Worldsasemergententities 46
2.2. Emergenceinpractice 48
2.3. Instantiationandtherelationbetweentheories 53
2.4. Thesituationinquantummechanics 59
3. Chaos,Decoherence,andBranching 64
3.1. Introduction:emergentclassicality 64
3.2. Emergentquasi-classicalityinsimpleisolatedsystems 65
3.3. Dynamicalpropertiesofisolatedquantumsystems 69
3.4. Theneedfordecoherence 74
3.5. Environment-induceddecoherence:asimplemodel 77
3.6. Environment-induceddecoherence:furtherdetails 81
3.7. Decoherenthistories 84
3.8. Analysingbranchingstructure 87
3.9. Thedecoherent-historiesframework 91
3.10. Decoherence,records,andconsistency 94
3.11. Howmanyworlds? 99
FirstInterlude 103