The Scientist As Philosopher

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The Scientist as Philosopher 3 Berlin Heidelberg New York Hong Kong London Milan Paris Tokyo Friedel Weinert The Scientist as Philosopher Philosophical Consequences of Great Scientiﬁc Discoveries

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13 Dr. Friedel Weinert University of Bradford Department of Social Sciences and Humanities Bradford BD7 1DP Great Britain e-mail: [email protected]

CoverﬁguresreproducedfromFaraday,M.:ACourseof6LecturesontheVariousForcesofMatter and Their Relation to Each Other. Ed. by W. Crookes (Grifﬁn, London, Glasgow 1860)

Library of Congress Cataloging-in-Publication Data. Weinert, Friedel, 1950– . The scientist as philosopher: philosophical consequences of great scientiﬁc discoveries Friedel Weinert. p.cm. Includes bibliographical references and index. ISBN 3-540-20580-2 (acid-free paper) 1. Discoveries in science. 2. Science–Philosophy. 3. Philosophy and science. I. Title Q180.55.D57W45 2004 501–dc22 2003064922

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Science has always had (...) a metaphoric function – that is, it generates an importantpartofaculture’ssymbolicvocabularyandprovidessomeofthe metaphysical bases and philosophical orientations of our ideology. As a consequence the methods of argument of science, its conceptions and its models, have permeated ﬁrst the intellectual life of the time, then the tenets and usages of everday life. All philosophies share with science the need to work with concepts such as space, time, quantity, matter, order, law, causality, veriﬁcation, reality. G. Holton, Einstein, History and Other Passions (2000), 43 Preface

This is not a philosophy of physics book. It is a book about how philosophy inspires physics and how physics influences philosophy. One section touches on biology. The reader will find in the following pages a study of the interaction between science and philosophy, with particular emphasis on physics. Philosophy offers science very general notions or presuppositions. Through scientific discoveries, these notions often become questionable and may undergo revision. Scientific discoveries therefore have consequences for philosophical thought. The great scientists are often aware of these lines of influence. This explains my title and subtitle. The In- troduction elaborates that the interaction concerns the notions of Nature, Physical Understanding, Time, Causation and Determinism. This volume was written in the reverse order from the way it is presented now. This was an accident of discovery. I first became aware of the scientists’ involvement with philosophy in discussions regarding the understanding of quantum physics. During the time of the composition of this book I have benefited from the un- wavering support of my colleagues and friends Anthony O’Hear and Roger Fellows. Peter Galison invited me to the Department of the History of Science at Harvard University as a research fellow. Lawrence Sklar received me for a research visit at the University of Michigan. Both offered encouragement and general advice on the manuscript, for which I am very grateful. Gerald Holton at Harvard read part of the manuscript and made some useful suggestions. I was the recipient of a generous grant for my research stay in the United States. I would like to thank the Leverhulme Trust for supporting me with a Leverhulme Study Abroad Fellowship. Thank you to Peter Galison, Lawrence Sklar and Nancy Cartwright for acting as referees. Steven French of Leeds University and Brigitte Falkenburg of the University of Dortmund read the whole manuscript. They offered valuable advice, which I acknowledge here. I would like to thank them for their constructive criticism and generosity. As usual any remaining errors will have to be my responsibility. Finally, my editor at Springer-Verlag, Angela Lahee, has been very helpful and supportive. I hope the reader will enjoy reading this study as much as I enjoyed writing it.

Bradford, January 2004 Friedel Weinert Contents

1Introduction...... 1

Part I The Philosopher Scientist

2TheConceptofNature...... 9 2.1 Introduction...... 9 2.2 FromtheOrganismictotheMechanisticUniverse...... 10 2.3 FromNaturestoNature...... 13 2.3.1 A Nominalist Critique of Scholastic Natures – RobertBoyle...... 13 2.3.2 CorpuscularPhilosophy...... 20 2.4 TheEmergenceofNatureasanInterrelatedSystem...... 22 2.4.1 Immanuel Kant ...... 24 2.4.2 Alexander von Humboldt ...... 27 2.5 The End of Philosophical Speculations About Nature as a System . . 29 2.5.1 CharlesDarwin...... 30 2.5.2 TheDiscoveryofAtomicStructure...... 32 2.5.3 Thermodynamics...... 33 InterludeA.Causation,DeterminismandTime...... 36 2.5.4 PhysicalFields...... 42 Interlude B. Models and Physical Understanding ...... 45 2.6 Fields, Structure Laws and the Decline oftheMechanicalWorldview ...... 47 2.6.1 Four-DimensionalReality...... 50 2.6.2 MetaphysicalAspectsofRelativity ...... 52 2.7 TheDemiseofthePointParticle:TheWave-ParticleDuality...... 56 Interlude C. The Concept of Nature and the Fundamental Notions . 61 2.8 InvarianceandReality...... 62 XContents

3 Physical Understanding ...... 75 3.1 Understanding and Fundamental Concepts ...... 75 3.2 Models...... 84 3.3 Einstein’sProblem,Bohr’sChallengeandtheFeedbackThesis..... 94

Part II The Scientist Philosopher

4TheBlockUniverse...... 105 4.1 Introduction...... 105 4.1.1 ModelsofTime...... 106 4.1.2 NaturalandConventionalUnitsofTime...... 108 4.1.3 Galileo’sPhysicalTime ...... 110 4.1.4 Newton’sAbsoluteandUniversalTime ...... 112 4.1.5 TheRelationalViewofTime ...... 117 4.2 The Special Theory of Relativity andtheIdeaoftheBlockUniverse...... 120 4.2.1 The Special Theory of Relativity (1905) – Some Results .... 120 4.2.2 TheSpecialTheoryofRelativityandModelsofTime...... 125 4.2.3 The Special Theory of Relativity – Some Early Reactions . . . 125 4.2.4 The First Step: Einstein and the Idea of the Block Universe . 128 4.2.5 The Second Step: Idealism and Determinism – New Models of Physical Understanding ...... 138 4.3 IdealistViewsofTime...... 147 4.3.1 SaintAugustine...... 147 4.3.2 Immanuel Kant ...... 151 4.3.3 Transience:OnthePassageofTime...... 155 4.4 MinkowskiSpace-Time ...... 160 4.4.1 Philosophical Consequences I: The Philosophy of Being . . . 171 4.4.2 Philosophical Consequences II: The Philosophy of Becoming181 4.4.3 TheEmergenceofTime...... 188

5 Causation and Determinism ...... 193 5.1 LaplaceandtheClassicalWorld...... 193 5.1.1 RisingShadows...... 193 5.1.2 Laplace’sGripontheClassicalWorld...... 195 5.1.3 TheFunctionalModelofCausation...... 202 5.1.4 Keeping Causation and Determinism Apart – Classical Style 208 5.2 NewDiscoveries–NewIdeas...... 212 5.2.1 Planck’sConstant...... 212 5.2.2 RadioactiveDecay...... 216 5.2.3 SpontaneousEmissions...... 217 5.2.4 Awakening Doubts and the Rutherford-Bohr Model oftheAtom...... 219 Contents XI

5.3 ScientistsDrawPhilosophicalConsequences...... 221 5.3.1 ConservativeResponse...... 224 5.3.2 TheRadicalResponse...... 230 Interlude D. Entanglement and the States of a Quantum System . . . 238 5.3.3 PhilosophicalResponse...... 248 5.3.4 SomeCausalStoriesinQuantumMechanics ...... 252 TheParticlePicture...... 253 TheWavePicture...... 256 5.3.5 TheConditionalModelofCausation...... 259 5.3.6 CausalExplanations...... 267 Interlude E. The Programme of Decoherence ...... 272 5.3.7 CausationWithoutDeterminism...... 275

6 Conclusion ...... 277

Bibliography ...... 283

List of Figure Sources ...... 319

Name Index ...... 321

Subject Index ...... 325