The age of entanglement : when quantum physics was reborn

413 Pages·2008·3.45 MB·English

by  Gilder

CONTENTS
Title Page
Dedication
Epigraph
List of Illustrations
A Note to the Reader
Introduction: Entanglement
1:The Socks1978 and 1981
The Arguments 1909–1935
2:Quantized LightSeptember 1909–June 1913
3:The Quantized AtomNovember 1913
4:The Unpicturable Quantum WorldSummer 1921
5:On the StreetcarSummer 1923
6:Light Waves and Matter WavesNovember 1923–December 1924
7:Pauli and Heisenberg at the MoviesJanuary 8, 1925
8:Heisenberg in HelgolandJune 1925
9:Schrödinger in ArosaChristmas and New Year’s Day 1925–1926
10:What You Can ObserveApril 28 and Summer 1926
11:This Damned Quantum JumpingOctober 1926
12:UncertaintyWinter 1926–1927
13:Solvay1927
14:The Spinning World1927–1929
15:Solvay1930
INTERLUDE:Things Fall Apart1931–1933
16:The Quantum-Mechanical Description of Reality1934–1935
The Search and the Indictment 1940–1952
17:PrincetonApril–June 10, 1949
18:Berkeley1941–1945
19:Quantum Theoryat Princeton1946–1948 192
20:PrincetonJune 15–December 194
21: Quantum Theory 1951
22:Hidden Variables and Hiding Out1951–1952
23:Brazil1952
24:Letters from the World1952
25:Standing Up to Oppenheimer1952–1957
26:Letters from Einstein1952–1954
Epilogue to the Story of Bohm1954
The Discovery 1952–1979
27:Things Change1952
28:What Is Proved by Impossibility Proofs1963–1964
29:A Little Imagination1969
30:Nothing Simple About Experimental Physics1971–1975
31:In Which the Settings Are Changed1975–1982
Entanglement Comes of Age 1981–2005
32:Schrödinger’s Centennial1987
33:Counting to Three1985–1988
34:“Against ‘Measurement’”1989–1990
35:Are You Telling Me This Could Be Practical?1989–1991
36:The Turn of the Millennium1997–2002
37:A Mystery, Perhaps1981–2006
Epilogue: Back in Vienna 2005
Glossary
Longer Summaries
Notes
Bibliography
Acknowledgments
Permissions
About the Author
Copyright
For my father
If people do not believe that mathematics is simple, it is only because they do not
realize how complicated life is.
—John von Neumann
LIST OF ILLUSTRATIONS
ALL BY THE AUTHOR UNLESS NOTED
John Stewart Bell
Reinhold Bertlmann
Fig.1:Bertlmann’ssocksandthenatureofreality,1980(JohnBell,courtesyofJournaldephysique
C2, Tome 42, 1981)
AlbertEinsteinandPaulEhrenfest,ca.1920(OriginalwatercolorbyMarykeKammerlinghOnnes,
courtesy AIP Emilio Segre Visual Archives)
Niels Bohr
Werner Heisenberg
Wolfgang Pauli, 1930(Gregor Rabinovitch)
Erwin Schrödinger
Max Born
P.A.M. Dirac in The Copenhagen Faust, 1932 (George Gamow, reproduced in Thirty Years That
Shook Physics,1985, courtesy of Dover Publications, Inc.)
David Bohm
John F. Clauser with his machine inspired by John S. Bell(Courtesy of LBL Graphic Arts, 1976)
Abner Shimony
John Clauser, Stuart J. Freedman, and their machine
Inside Freedman and Clauser’s Bell-machine
Richard Holt
Alain Aspect
Anton Zeilinger, Daniel Greenberger, and Michael Horne’s hat
John Bell’s self-portrait (Courtesy of Reinhold Bertlmann)
Michael Horne
Artur Ekert
Nicolas Gisin
A NOTE TO THE READER
WernerHeisenberg,thepioneerwhofirstlaiddownthelawsofthefundamentalbehaviorofmatter
and light, was an old man when he sat down to write about his life. The book he wrote is not an
autobiography of the man but an autobiography of his intellect, entirely a series of reconstructed
conversations. His two most famous papers are solo affairs—one introducing quantum mechanics
(thelawsofthefundamentalbehaviorofmatterandlight)andtheotherontheuncertaintyprinciple
(which declares that at any given time, the more specific a particle’s position, the more vague its
speedanddirection,andviceversa).Buttherootsofeachsolitarypaperreachdeepintomonthsof
heated and careful conversation with most of the great names of quantum physics. “Science rests
on experiments,” wrote Heisenberg, but “science is rooted in conversations.”
Nothingcouldbefurtherfromtheimpressionphysicstextbooksgivetostudents.There,physics
seems to be a perfect sculpture sitting in a vacuum-sealed case, as if brains, only tenuously con-
nectedtobodies,hadgivenbirthtoinsightsfullyformed.TheseAthena-liketheoriesandZeus-like
theoristsseemshiny,glassy,smooth—sometimes,ifthelightisright,youcanseethroughtheminto
themysteriesandbeautiesofthephysicaluniverse;butthereishardlyatraceofhumanity,orany
sense of questions still to be answered.
Physics, in actuality, is a never-ending search made by human beings. Gods and angels do not
comebearingperfectlyformedtheoriestodisembodiedprophetswhoinstantlywritetextbooks.The
schoolbooksimplificationsobscurethecrooked,strange,andfascinatingpathsthatstretchoutfrom
eachidea,notonlybackintothepastbutalsoonwardintothefuture.Whileweaspiretouniversal-
ity and perfection, we are lying if we write as if we have achieved it.
Conversations are essential to science. But the off-the-cuff nature of conversation poses a dif-
ficulty. It is rare, even in these digital times, to have a complete transcript of every word spoken
betweentwopeopleonagivenday,evenifthatconversationsomedayleadstoanewunderstanding
oftheworld.Theresultisthathistorybooksrarelyhavemuchoftheto-and-froofhumaninterac-
tion. Heisenberg’s statement suggests that something is therefore lost.
WhenIfirststartedporingthroughthememoirsandbiographiesofthequantumphysicistsofthe
twentiethcentury,IfeltasifIwerewatchingamovie—thecastofcharacterswassovividandthe
plottwistssounexpected.Whilethestrengthofscienceisitsabilitytosloughoffthecontingencies
ofhistoryandreachtowardpureknowledge,thisknowledgeisbuilt,onepuzzlepieceatatime,by
peoplelivingtheirlivesinspecifictimesandplaceswithspecificpassions.Scienceunfoldsinsome
directionsratherthaninothersbecauseofcircumstances.Characters(notdisembodiedbrains)and
plot twists (not the relentless forward march of truth) almost guarantee that this is true.
AsTomWolfewroteatthebeginningofTheElectricKool-AidAcidTest:“Ihavetriednotonly
to tell what the Pranksters did but to re-create the mental atmosphere or subjective reality of it. I