(cid:1) (cid:1) (cid:1) (cid:1) Once Upon Einstein (cid:1) (cid:1) (cid:1) (cid:1) (cid:1) (cid:1) (cid:1) (cid:1) Once Upon Einstein Thibault Damour translated by Eric Novak AKPeters,Ltd. Wellesley,Massachusetts (cid:1) (cid:1) (cid:1) (cid:1) (cid:1) (cid:1) (cid:1) (cid:1) Editorial,Sales,andCustomerServiceOffice AKPeters,Ltd. 888WorcesterStreet,Suite230 Wellesley,MA02482 www.akpeters.com Copyright(cid:1)c 2006byAKPeters,Ltd. Allrightsreserved. Nopartofthematerialprotectedbythiscopyrightnoticemaybe reproducedorutilizedinanyform,electronicormechanical,includingphotocopy- ing, recording, or by any information storageand retrieval system, without written permissionfromthecopyrightowner. OriginallypublishedinFrench. SiEinsteinm’´etaitcont´e,copyright(cid:1)c LeChercheMidiEditeur,2005. EnglishtranslationbyEricNovak. LibraryofCongressCataloging-in-PublicationData Damour,Thibault. [SiEinsteinm’e´taitconte´.English] Onceuponeinstein/ThibaultDamour;translatedbyEricNovak. p.cm. Includesbibliographicalreferences. ISBN13:978-1-56881-289-2(alk.paper) ISBN10:1-56881-289-2(alk.paper) 1.Einstein,Albert,1879-1955.2.Physicists--Germany--History--20th century--Biography.3.Physicists--UnitedStates--History--20thcentury--Biography.4. Physics--History--20thcentury.I.Title. QC16.E5D358132006 530’.092--dc22 [B] 2005056604 Coverphotograph:AlbertEinsteinca.1930.CreditRuedesArchives/TAL. PrintedintheUnitedStatesofAmerica 1009080706 10987654321 (cid:1) (cid:1) (cid:1) (cid:1) (cid:1) (cid:1) (cid:1) (cid:1) ToThierry,whoshowedmethepath, toHe´le`ne,whosharedthepath, toFaxandUlysses,whowalkedwithmealongthepath. (cid:1) (cid:1) (cid:1) (cid:1) (cid:1) (cid:1) (cid:1) (cid:1) Contents OnceUponaTime... xi Acknowledgments xiii 1 TheQuestionofTime 1 TheEagleandtheSparrow . . . . . . . . . . . . . . . . . . . . . 1 SpaceandTimebeforeEinstein . . . . . . . . . . . . . . . . . . 6 Ether: TheMaterializationofAbsoluteSpace . . . . . . . . . . . 10 ButterfliesinaShip’sCabin . . . . . . . . . . . . . . . . . . . . 12 “TheStep” . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 TimeDeregulated . . . . . . . . . . . . . . . . . . . . . . . . . 18 TemporalRefrigerators . . . . . . . . . . . . . . . . . . . . . . . 21 AnInfiniteMultiplicityofDesynchronizedTimes . . . . . . . . . 24 2 TheWorld’sCheckerboard 27 “TimeDoesNotExist!” . . . . . . . . . . . . . . . . . . . . . . 27 BergsonandEinstein . . . . . . . . . . . . . . . . . . . . . . . . 29 ThePrincessedeGuermantesListenstoEinstein . . . . . . . . . 33 ANew“World”: Space-Time . . . . . . . . . . . . . . . . . . . 35 MethodologicalInterludeontheNotionof“Real” . . . . . . . . . 39 TheSpace-TimeBlock . . . . . . . . . . . . . . . . . . . . . . . 40 TheWorld’sCheckerboard . . . . . . . . . . . . . . . . . . . . . 42 ATenaciousIllusion . . . . . . . . . . . . . . . . . . . . . . . . 47 Lorentz,Poincare´,Einstein,Minkowski,andSpecialRelativity . . 48 EphemeralMatter . . . . . . . . . . . . . . . . . . . . . . . . . 52 AProfoundSimplificationoftheBasicCategoriesofReality . . . . 55 3 ElasticSpace-Time 57 NewtonUnthroned . . . . . . . . . . . . . . . . . . . . . . . . 57 SuddenlyFamous . . . . . . . . . . . . . . . . . . . . . . . . . 60 “TheHappiestThoughtofMyLife” . . . . . . . . . . . . . . . . 61 vii (cid:1) (cid:1) (cid:1) (cid:1) (cid:1) (cid:1) (cid:1) viii Contents Einstein’sElevator . . . . . . . . . . . . . . . . . . . . . . . . . 63 TowardsaGeneralizedRelativity . . . . . . . . . . . . . . . . . . 65 Einstein’sTheoryinaPhraseandanImage . . . . . . . . . . . . 66 Space-TimeDeformed . . . . . . . . . . . . . . . . . . . . . . . 68 Einstein’sLawofSpace-TimeElasticity . . . . . . . . . . . . . . 73 TheStrengthofSpace-TimeElasticity . . . . . . . . . . . . . . . 82 4 Einstein’sWorld-Game 85 MercuryAdvances,theSphinxSpeaks . . . . . . . . . . . . . . . 85 VibrationalWavesintheSpace-TimeGelatin . . . . . . . . . . . 88 ThinkingoftheWhole . . . . . . . . . . . . . . . . . . . . . . 92 LargeSpace-TimeDeformations: NeutronStarsandBlackHoles . 96 5 LightandEnergyinGrains 103 “AnElementVaryingbyJumps” . . . . . . . . . . . . . . . . . . 103 A“VeryRevolutionary”Idea . . . . . . . . . . . . . . . . . . . . 107 TheWaveNatureofLight . . . . . . . . . . . . . . . . . . . . . 109 TheWormwithintheFruit . . . . . . . . . . . . . . . . . . . . 109 TheBlackandtheRed . . . . . . . . . . . . . . . . . . . . . . . 111 DisorderandCountingtheConfigurationsofFleas . . . . . . . . 113 EntropyandDisorder . . . . . . . . . . . . . . . . . . . . . . . 115 TheNeglectedEquation: E=hf . . . . . . . . . . . . . . . . . . 116 FirstConsequencesoftheNeglectedEquation . . . . . . . . . . . 117 MatterandQuanta . . . . . . . . . . . . . . . . . . . . . . . . 119 TheIcyDiamond . . . . . . . . . . . . . . . . . . . . . . . . . 120 TheIdeabehindtheLaser . . . . . . . . . . . . . . . . . . . . . 122 LightandMatter . . . . . . . . . . . . . . . . . . . . . . . . . . 125 6 ConfrontingtheSphinx 129 ACrucialConversation . . . . . . . . . . . . . . . . . . . . . . 129 “WavesoverHere,QuantaoverThere!” . . . . . . . . . . . . . . 132 Einstein’sGhostField,Born’sProbabilityAmplitude,and Heisenberg’sUncertaintyRelations . . . . . . . . . . . . . 134 AWatershedMoment . . . . . . . . . . . . . . . . . . . . . . . 137 “TheMarbleSmileofImplacableNature” . . . . . . . . . . . . . 139 AdventurersinEntangledReality . . . . . . . . . . . . . . . . . 141 (cid:1) (cid:1) (cid:1) (cid:1) (cid:1) (cid:1) (cid:1) (cid:1) Contents ix 7 Einstein’sLegacy 147 TheMouseandtheUniverse . . . . . . . . . . . . . . . . . . . . 147 TheMultipleWorld . . . . . . . . . . . . . . . . . . . . . . . . 151 TheKantianQuantum . . . . . . . . . . . . . . . . . . . . . . 156 TheGrandIllusions . . . . . . . . . . . . . . . . . . . . . . . . 158 DreamsofUnification . . . . . . . . . . . . . . . . . . . . . . . 160 NotaDaywithoutEinstein . . . . . . . . . . . . . . . . . . . . 162 OfBearsandMen . . . . . . . . . . . . . . . . . . . . . . . . . 165 Notes 167 SelectBibliography 183 (cid:1) (cid:1) (cid:1) (cid:1) (cid:1) (cid:1) (cid:1) (cid:1) Once Upon a Time . . . Once upon a time, there was a five-year-old boy, lying ill in bed. To help him pass the time, his father brought him a compass. The child was struck by the strangeness of the magnetic needle. In place of what he had come to expect, the usual behavior of mundane objects, the needle always pointed in the same direction, however he might rotate the casing. How could some- thingsoextraordinarybepossible? Whatwasthehiddencauseofthisstrange behavior? The boy’s name was Albert Einstein. For his entire life, he remembered the profound astonishment brought to him by the compass. This event was the first manifestation of what would guide him throughout his career: an insatiable curiosity, a desire to grasp the hidden order beneath the surface ap- pearanceofthings. Ashestatedit: IknowperfectlywellthatImyselfhavenospecialtalents. Itwascuriosity, obsession,andsheerperseverancethatbroughtmetomyideas. It has been 100 years since the “miraculous year,” 1905, during which Einsteinlaidthefoundationsoftwoofthecrowningscientifictheoriesofthe twentiethcentury: specialrelativityandquantummechanics. Ithasbeen90 years since he completed the theory of general relativity, and 50 years since his death. Still the name Albert Einstein continues to fascinate the scientist as well as the man on the street. His life was rich and complex, but it was guided by this single, simple desire: to understand the hidden order of the universe. Hissuccessinthisquestwasextraordinary. Evenifthesecondpart of his life brought fewer concrete results than the first, the great ambition of his curiosity can be measured today by the fact that the questions which he posedthenhaveonlyrecentlybeguntobeanswered. This book is not a biography of Einstein. We shall hardly speak of Ein- stein the husband, the father, the musician, the pacifist, or the Zionist. We shall not discuss his youth in Munich, his studies in Zurich, his difficulty in finding a job, his university career, his social life in the vibrant Berlin of xi (cid:1) (cid:1) (cid:1) (cid:1)