The age of entanglement

www.pdfgrip.com CONTENTS Title Page Dedication Epigraph List of Illustrations A Note to the Reader Introduction: Entanglement 1: The Socks 1978 and 1981 The Arguments 1909–1935 2: Quantized Light September 1909–June 1913 3: The Quantized Atom November 1913 4: The Unpicturable Quantum World Summer 1921 5: On the Streetcar Summer 1923 6: Light Waves and Matter Waves November 1923–December 1924 7: Pauli and Heisenberg at the Movies January 8, 1925 8: Heisenberg in Helgoland June 1925 9: Schrödinger in Arosa Christmas and New Year’s Day 1925–1926 10: What You Can Observe April 28 and Summer 1926 11: This Damned Quantum Jumping October 1926 12: Uncertainty Winter 1926–1927 13: Solvay 1927 www.pdfgrip.com 14: The Spinning World 1927–1929 15: Solvay 1930 INTERLUDE: Things Fall Apart 1931–1933 16: The Quantum-Mechanical Description of Reality 1934–1935 The Search and the Indictment 1940–1952 17: Princeton April–June 10, 1949 18: Berkeley 1941–1945 19:Quantum Theory at Princeton 1946–1948 192 20: Princeton June 15–December 194 21: Quantum Theory 1951 22: Hidden Variables and Hiding Out 1951–1952 23: Brazil 1952 24: Letters from the World 1952 25: Standing Up to Oppenheimer 1952–1957 26: Letters from Einstein 1952–1954 Epilogue to the Story of Bohm 1954 The Discovery 1952–1979 27: Things Change 1952 28: What Is Proved by Impossibility Proofs 1963–1964 29: A Little Imagination 1969 30: Nothing Simple About Experimental Physics 1971–1975 31: In Which the Settings Are Changed 1975–1982 Entanglement Comes of Age 1981–2005 www.pdfgrip.com 32: Schrödinger’s Centennial 1987 33: Counting to Three 1985–1988 34: “Against ‘Measurement’” 1989–1990 35: Are You Telling Me This Could Be Practical? 1989–1991 36: The Turn of the Millennium 1997–2002 37: A Mystery, Perhaps 1981–2006 Epilogue: Back in Vienna 2005 Glossary Longer Summaries Notes Bibliography Acknowledgments Permissions About the Author Copyright www.pdfgrip.com For my father www.pdfgrip.com If people not believe that mathematics is simple, it is only because they not realize how complicated life is —John von Neumann www.pdfgrip.com LIST OF ILLUSTRATIONS ALL BY THE AUTHOR UNLESS NOTED John Stewart Bell Reinhold Bertlmann Fig 1: Bertlmann’s socks and the nature of reality, 1980 (John Bell, courtesy of Journal de physique C2, Tome 42, 1981) Albert Einstein and Paul Ehrenfest, ca 1920 (Original watercolor by Maryke Kammerlingh Onnes, 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 www.pdfgrip.com John Bell’s self-portrait (Courtesy of Reinhold Bertlmann) Michael Horne Artur Ekert Nicolas Gisin www.pdfgrip.com A NOTE TO THE READER Werner Heisenberg, the pioneer who first laid down the laws of the fundamental behavior of matter 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 (the laws of the fundamental behavior of matter and light) and the other on the uncertainty principle (which declares that at any given time, the more specific a particle’s position, the more vague its speed and direction, and vice versa) But the roots of each solitary paper reach deep into months of 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.” Nothing could be further from the impression physics textbooks give to students There, physics seems to be a perfect sculpture sitting in a vacuum-sealed case, as if brains, only tenuously connected to bodies, had given birth to insights fully formed These Athena-like theories and Zeus-like theorists seem shiny, glassy, smooth—sometimes, if the light is right, you can see through them into the mysteries and beauties of the physical universe; but there is hardly a trace of humanity, or any sense of questions still to be answered Physics, in actuality, is a never-ending search made by human beings Gods and angels not come bearing perfectly formed theories to disembodied prophets who instantly write textbooks The schoolbook simplifications obscure the crooked, strange, and fascinating paths that stretch out from each idea, not only back into the past but also onward into the future While we aspire to universality 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 difficulty It is rare, even in these digital times, to have a complete transcript of every word spoken between two people on a given day, even if that conversation someday leads to a new understanding of the world The result is that history books rarely have much of the to-and-fro of human interaction Heisenberg’s statement suggests that something is therefore lost When I first started poring through the memoirs and biographies of the quantum physicists of the twentieth century, I felt as if I were watching a movie—the cast of characters was so vivid and the plot twists so unexpected While the strength of science is its ability to slough off the contingencies of history and reach toward pure knowledge, this knowledge is built, one puzzle piece at a time, by people living their lives in specific times and places with specific passions Science unfolds in some directions rather than in others because of circumstances Characters (not disembodied brains) and plot twists (not the relentless forward march of truth) almost guarantee that this is true As Tom Wolfe wrote at the beginning of The Electric Kool-Aid Acid Test: “I have tried not only to tell what the Pranksters did but to re-create the mental atmosphere or subjective reality of it I www.pdfgrip.com Age Cambridge, England: Cambridge University Press, 1990 ——— “Is the Moon There When Nobody Looks?” in Richard Boyd, Philip Gasper, and J D Trout, eds., The Philosophy of Science Cambridge, MA: M.I.T Press, 1993 ——— “What’s Wrong with These Elements of Reality?,” Physics Today, June 1990, 9–11 Michelmore, Peter Einstein, Profile of the Man New York: Dodd, Mead, 1962 Miller, A I., ed Sixty-two Years of Uncertainty New York: Plenum Press, 1990 An amazing conference proceedings, including John Bell, “Against ‘Measurement’” Michael Horne, Abner Shimony, and Anton Zeilinger, “Introduction to Two-Particle Interferometry” Don Howard, “Nicht Sein Kann Was Nicht Sein Darf, or, The Prehistory of EPR, 1909–1935: Einstein’s Early Worries About the Quantum Mechanics of Composite Systems” Arthur I Miller, “Imagery, Probability, and the Roots of the Uncertainty Principle.” Moore, Walter Schrödinger: Life and Thought Cambridge, England: Cambridge University Press, 1990 Nasar, Sylvia A Beautiful Mind New York: Touchstone, 1998 Nolte, David Mind at Light Speed New York: Free Press, 2001 In the Matter of J Robert Oppenheimer: Transcript of Hearing before Personnel Security Board April 12–May 6, 1954 Cambridge, MA: M.I.T Press, 1970 Pais, Abraham Einstein Lived Here (the companion volume to ‘Subtle Is the Lord…’) Oxford: Oxford University Press, 1994 ——— Inward Bound: Of Matter and Forces in the Physical World Oxford: Oxford University Press, 1986 ——— Niels Bohr’s Times in Physics, Philosophy, and Polity Oxford: Oxford University Press, 1991 ——— ‘Subtle Is the Lord…’: The Science and the Life of Albert Einstein Oxford: Oxford University Press, 1982 Pauli, Wolfgang Writings on Physics and Philosophy Charles P Enz and Karl von Meyenn, eds Robert Schlapp, trans Berlin: Springer-Verlag, 1994 Pauli, Wolfgang, and C G Jung Atom and Archetype: The Pauli-Jung Letters 1932–1958 C A Meier, ed Princeton, NJ: Princeton University Press, 2001 Peat, F David Infinite Potential: The Life and Times of David Bohm Reading, MA: Addison-Wesley, 1997 www.pdfgrip.com Peierls, Rudolf Bird of Passage Princeton, NJ: Princeton University Press, 1985 ——— Surprises in Theoretical Physics Princeton, NJ: Princeton University Press, 1979 Penrose, Roger The Emperor’s New Mind: Concerning Computers, Minds, and the Laws of Physics Oxford: Oxford University Press, 2002 Przibram, K., ed Letters on Wave Mechanics: Schrödinger-Planck-Einstein-Lorentz New York: Philosophical Library, 1967 Rabi, I I., Robert Serber, Victor Weisskopf, Abraham Pais, and Glenn Seaborg Oppenheimer New York: Charles Scribner’s Sons, 1969 Rajaraman, Ramamurti “Fractional Charge,” invited lecture at the international conference “Quantum (Un)speakables” in honor of John S Bell, Vienna, November 10–14, 2000 ——— “John Stewart Bell: The Man and His Physics,” unpublished paper Raman, V V., and Paul Forman “Why Was It Schrödinger Who Developed de Broglie’s Ideas?” Historical Studies in the Physical Sciences, Vol I, 1969, 294–96 Regis, Ed Who Got Einstein’s Office? Eccentricity and Genius at the Institute for Advanced Study Reading, MA: Addison-Wesley, 1988 Rozental, S., ed Niels Bohr: His Life and Work as Seen by His Friends and Colleagues Amsterdam: North Holland Pub Co., 1967 Satinover, Jeffrey “Jung and Pauli,” unpublished paper Saunders, Thomas J Hollywood in Berlin Berkeley: University of California Press, 1994 Schlipp, P A., ed Albert Einstein: Philosopher-Scientist New York: MJF Books, 1970 Schrödinger, Erwin “Discussion of Probability Relations between Separated Systems,” Proceedings of the Cambridge Philosophical Society 31, 555–63 (1935) ——— The Interpretation of Quantum Mechanics Michel Bitbol, ed., Woodbridge, CT: Ox Bow Press, 1995 ——— What Is Life? And Other Scientific Essays New York: Doubleday Anchor Books, 1956 Schweber, S S In the Shadow of the Bomb Princeton, NJ: Princeton University Press, 2000 Segrè, Gino Faust in Copenhagen New York: Viking, 2007 www.pdfgrip.com Shimony, Abner “Metaphysical Problems in the Foundations of Quantum Mechanics,” in The Philosophy of Science Richard Boyd, Philip Gasper, and J D Trout, eds Cambridge, MA: M.I.T Press, 1993 ——— The Search for a Naturalistic Worldview, Vol Cambridge, MA: Cambridge University Press, 1993 Shimony, Abner, M A Horne, and J F Clauser, “Comment on the Theory of Local Beables” Shimony, “Reply to Bell,” Dialectica 39, No 2, 97–110 (1985) Shimony, Abner, Valentine Telegdi, and Martinus Veltman Obituary: “John S Bell,” Physics Today 82 (Aug 1991) Smith, Alice Kimball, and Charles Weiner, eds Robert Oppenheimer Letters and Recollections Stanford, CA: Stanford University Press, 1980 Stachel, John, ed Einstein’s Miraculous Year: Papers That Changed the Face of Physics Princeton, NJ: Princeton University Press, 1998 Teller, Edward, Memoirs: A Twentieth-Century Journey in Science and Politics Cambridge, MA: Perseus Publishing, 2001 Tomonaga, Sinitiro The Story of Spin Takeshi Oka, trans Chicago: University of Chicago Press, 1997 Townes, Charles How the Laser Happened Oxford: Oxford University Press, 1999 Uhlenbeck, George E “Reminiscences of Professor Paul Ehrenfest,” American Journal of Physics 24, 431–33 (1956) Uhlenbeck, George E., and Samuel A Goudsmit “Spinning Electrons and the Structure of Spectra,” Nature 117, 264–65 (1926) Wang, Hao Reflections on Kurt Gödel Cambridge, MA: M.I.T Press, 1987 Weaver, Jefferson Hane The World of Physics: A Small Library of the Literature of Physics from Antiquity to the Present (Vol II: The Einstein Universe and the Bohr Atom) New York: Simon & Schuster, 1987 Weinberg, Steven The Discovery of Subatomic Particles New York: Scientific American Books, 1983 Weisskopf, Victor F Physics in the Twentieth Century: Selected Essays Cambridge, MA: M.I.T Press, 1972 www.pdfgrip.com Wheeler, J A., and W H Zurek, eds Quantum Theory and Measurement Princeton, NJ: Princeton University Press, 1983 Whitaker, Andrew Einstein, Bohr, and the Quantum Dilemma Cambridge, England: Cambridge University Press, 1996 ——— “John Bell and the Most Profound Discovery of Science,” Physics World, December 1998, 29–34 Wick, David The Infamous Boundary: Seven Decades of Heresy in Quantum Physics New York: Copernicus, Springer, 1995 Woolf, Harry, ed Some Strangeness in the Proportion: A Centennial Symposium to Celebrate the Achievements of Albert Einstein Reading, MA: Addison-Wesley, 1980 THREE WEB SITES THAT WERE EXTREMELY HELPFUL The Nobel Prize Web site: www.nobel.se/physics/laureates This amazing site contains a short biography or autobiography for each laureate, and gives the texts of all the Nobel lectures J J O’Connor and E F Robertson’s “MacTutor” Web site: biographies of mathematicians (and many physicists): www-groups.dcs.st-and.ac.uk/~history/ This is a well-researched encyclopedia of well-written short biographies The arXiv: http://arXiv.org The “quant-ph” section of this Web site these days is the first publication site of many of the most important and interesting quantum information theory papers ARTICLES ON QUANTUM COMPUTING AND CRYPTOGRAPHY The Quantum Information issue of Physics World 11, No 3, 35–57 (March 1998) Fitzgerald, Richard “What Really Gives a Quantum Computer Its Power?,” Physics Today, 20–22 (January 2000) Gisin, Nicolas, Grégoire Ribordy, Wolfgang Tittel, and Hugo Zbinden, “Quantum Cryptography,” Reviews of Modern Physics 74, 145ff (January 2002) Grover, Lov “Quantum Computing,” The Sciences, 24–30 (July 1999) Lloyd, Seth “A Potentially Realizable Quantum Computer,” Science, 261 (1993) ——— “Quantum Mechanical Computers,” Scientific American, 140–45 (October 1995) Naik, D S., C G Peterson, A G White, A J Berglund, and P G Kwiat “Entangled State Quantum Cryptography: Eavesdropping on the Ekert Protocol,” Phys Rev Letters 84, 4733 (2000) www.pdfgrip.com Nielsen, Michael A “Rules for a Complex Quantum World,” Scientific American, 66–75 (November 2002) HELPFUL GLOSSARIES/ENCYCLOPEDIAS FOR THE GENERAL READER Q Is for Quantum: An Encyclopedia of Particle Physics, by John Gribbin (Mary Gribbin, ed.; Jonathan Gribbin, illus.; Benjamin Gribbin, time lines) New York: The Free Press, 1998 Oxford Dictionary of Physics Alan Isaacs, ed Oxford: Oxford University Press, 2003 THE MOST ENJOYABLE INTRODUCTION TO THE QUANTUM THEORY IS The Einstein Paradox and Other Science Mysteries Solved by SHERLOCK HOLMES, by Colin Bruce Reading, MA: Helix Books, 1997 www.pdfgrip.com ACKNOWLEDGMENTS George Gamow’s Thirty Years That Shook Physics and David Mermin’s essay “Quantum Mysteries for Anyone” inspired this book, and it would not have been possible without Abraham Pais’s incredible trilogy, “Subtle Is the Lord,” Niels Bohr’s Times, and Inward Bound There are four people the thought of whom makes me glad I wrote this book, just because it led me to them: to Reinhold and Renate Bertlmann, George Johnson, and Miriam Yevick, I am endlessly grateful Many, many thanks to everyone I sought out for memories or explanations It was a privilege to meet so many wonderful, fascinating people In particular, thanks to Abner Shimony and Roman Jackiw, who were the first, and crucially guided my thinking and writing Thanks to Alain Aspect, Mary Bell, Andy Berglund, John Clauser, Eugene Commins, Artur Ekert, Ed Fry, Ken Ford, Stuart Freedman, John Hart, Dick Holt, Mike Horne, Danny Greenberger, George Greenstein (and his wonderful book with Arthur Zajonc), Nicolas Gisin, Lars Becker Larsen, Seth Lloyd, David Mermin, Robert Podolsky, Dave Rehder, Terry Rudolph, Ramamurti Rajaraman, Jack Steinberger, Jeff Satinover, David Sutherland, and Miriam and George Yevick Thanks also to Steve Weinstein, who gave me The Shaky Game; and especially to Andrew Whitaker, for writing the beautiful Einstein, Bohr, and the Quantum Dilemma, and to Chris Fuchs for his wonderful samizdat, Notes on a Paulian Idea—these two books sat on my desk rather than on the shelf Many thanks to the people who read and commented on part or all of the book: Matt Babineau (whose perceptive comments on the text in 2002 were still guiding me years later), George, Mellie, and Josh Gilder, Donny Fraits, Anne Palmer, Sorina Higgins, Reinhold and Renate Bertlmann, Abner Shimony, Miriam Yevick, Dick Holt, Nicolas Gisin, John Hart, Jeff Satinover, Miles Blencowe, Herschel Snodgrass and his fall 2006 quantum mechanics class at Lewis & Clark, and Patty Karlin, who introduced me to Herschel Thanks to Henning Makholm for his description of the Copenhagen main railway station and to Barbara Palmer for descriptions of Munich and its movie theaters Thanks to Miles Blencowe, who took on a physics minor in an independent study of entanglement with clarity and good humor Thanks to Carver Mead for his kindness and his vision of quantum mechanical coherency Thanks to Sue Godsell and to Birk-beck College for access to and help with the Bohm archives Thanks to Matyas Koniorczyk, friend and guide during my first conference in Vienna in 2000, and to the late Fred Balderston, who made Berkeley a welcoming place Thanks to Alexander Stibor for a wonderful day in Vienna in 2005 and for insisting that I encounter both the Summer Palace and Terry Rudolph; and to Lee Smolin and Herb Bernstein for a beautiful dinner www.pdfgrip.com Thanks to Louis, America, and Isabella von Harnier, who took me on a magical trip to the Walchensee, where we found Heisenberg’s house; and to my cousins Stefan and Helena, Damien, Cheka, and Thèresè von Gatterberg, for the white asparagus and the two-hour Black Forest motorcycle ride to the church where Born met Schweitzer; and to Constantin and Gundi von Gatterburg, who fed me a magnificent meal and drove me to the airport, all at the last minute Thanks to Doug Hagen, who taught me to be a projectionist, which made supporting myself while writing a lot more fun Thanks to Dakota Reiss, who provided moral and feline support; and to my cousin Jeremy Gordinier, who stayed up all night turning my drawings into digital copies on a computer completely unfit for the task Thanks to Bruce Chapman, who helped me at an hour of need with kindness and financial support, and to Katy Young, for last-minute, long-distance library assistance Thanks to my agent and cousin-by-marriage, Nina Ryan, for all her work and sympathetic encouragement Thanks to Avelina Truchero, for the homemade fudge! And huge thanks to Roxanne Urrey, without whose kindness and self-sacrificial help in a time of need I would have been lost Thanks to Natalia Davis, who gave me space to write for a year and a half in the Oakland hills and several times provided critical moral support Thanks to Shona Campbell and Brandon Guenther of the Valley Ford Hotel (the best kitchen-saloon-inn in Sonoma County), who provided beautiful work space and terrific locally grown food at various critical moments in the endgame Thanks to everyone at Knopf who has worked on those endless stacks of manuscript pages, including Kate Norris for her careful and sensitive copyediting, Meghan Wilson for her calm and indispensable help, and especially thanks to my editor, Jonathan Segal, whose guidance tightened the shaggy, rambling manuscript until it became a united book, and his awesome assistants, Kyle McCarthy and Joey McGarvey Finally, thanks to all my friends and family for their support and good humor Particularly, so many thanks to my mom, Cornelia Brooke Gilder, who wrote two books during the eight years of this book’s gestation; for several years we worked side by side in the “Temple” above the garage, and the companionship, accountability, occasional gardening, and lunches on the porch were my best writing experiences; to my sister Mellie for much caffeinated work-companionship, most notably the simultaneous all nighter on opposite coasts; and to my dad, George Gilder, who was my mainstay as constant critical reader and running companion, and who always saw the big picture And thanks to Donny Fraits for accompanying me on the piano as I wrote www.pdfgrip.com PERMISSIONS Grateful acknowledgment is made to the following for permission to reprint previously published material: American Institute of Physics: Excerpt from “What’s Wrong with These Elements of Reality” by David Mermin (Physics Today, vol 43, no 6, 1990), copyright © 1990 by American Institute of Physics Reprinted by permission of American Institute of Physics Dover Publications, Inc.: Excerpt from Thirty Years That Shook Physics by George Gamow Reprinted by permission of Dover Publications, Inc International Commission on Physics Education: Excerpts from “Bohr and Heisenberg” by Carl Friedrich von Weizsäcker from Niels Bohr: A Centenary Volume, edited and translated by A.P French and P.J Kennedy (Cambridge: Harvard University Press, 1985) Reprinted by permission of International Commission on Physics Education The MIT Press: Excerpt from The Character of Physical Law by Richard Feynman Reprinted by permission of The MIT Press Michael Nauenberg: Excerpt from “The Moral Aspect of Quantum Mechanics” by John S Bell and Michael Nauenberg from Preludes in Theoretical Physics, edited by A De Shalit, H Feshbach, and L Van Hove (Amsterdam: North-Hollans Physics Publishing, 1966) Reprinted by per mission of Michael Nauenberg Physics World: Excerpt from “Against Measurement” by John S Bell (Physics World, August 1990) Reprinted by permission of Physics World www.pdfgrip.com Springer Science and Business Media: Excerpt from “Simulating Physics with Computers” by Richard Feynman ( International Journal of Theoretical Physics, vol 21, nos 6/7, 1982) Reprinted by permission of Springer Science and Business Media University of California Press: Excerpt from Galgenlieder (The Gallows Song) by Christian Morgenstern, edited and translated by Max E Knight, copyright © 1963 by Max E Knight Reprinted by permission of the University of California Press www.pdfgrip.com A NOTE ABOUT THE AUTHOR Louisa Gilder was born in Tyringham, Western Massachusetts She lives in Bodega, Northern California This is her first book www.pdfgrip.com FOOTNOTES *1 A paper is considered famous if it has been cited in more than a hundred subsequent papers; Einstein’s monumental papers on special relativity (1905) and the quantum theory (1917) have each been cited more than seven hundred times; his 1905 Ph.D dissertation on the size of an atom, more than fifteen hundred times By contrast, twenty-five hundred papers in physics journals have cited Bell’s 1964 paper on entanglement; the same as for the 1935 Einstein-Podolsky-Rosen paper that inspired him Return to text *2 The words of both Hamlet and John Bell Return to text †3 Electricity-carrying subatomic particles that are a crucial component of all matter Return to text *4 In their paper “On a New Alkali Metal,” Bunsen and Kirchhoff explained that the name came from the Latin word caesius, which “the ancients used to designate the blue of the upper part of the firmament.” Return to text *5 A decade down the road, as a guest lecturer at the University of Tokyo, he would become fluent in Japanese, winning a prize for a haiku, and as a sideline to physics, he would specialize in the botany of cacti Return to text *6 A technical footnote: Sommerfeld was wrong only because neither he nor anyone else yet knew about spin He based his calculation on the atom’s quantized angular momentum, which indeed is a factor But silver, like hydrogen, has a single unpaired electron in its outermost (valence) energy level That electron’s spin (up or down) is what causes the binary response to the magnetic field If Stern and Gerlach had done the experiment with, for example, magnesium (which has a pair of electrons in its valence energy level), Sommerfeld would have been perfectly correct: the beam would have split into three Magnesium’s valence pair of electrons (one spins up, and one spins down) cancel out each other’s influence, so that spin is no longer an issue, and the three quantized valences of angular momentum create the three piles Return to text *7 It seems that the prize was deferred, at least in part, because of a stalemate resulting from the Academy’s skepticism over relativity, on one hand, and the growing pressure from theoretical physicists for Einstein to receive the prize, on the other Return to text *8 The periodic table, first laid out in the 1860s and 1870s by the visionary Dimitri Mendeleev, is a way of organizing the elements into rows (roughly) from lightest to heaviest: each column holds a group of elements with similar properties Bohr’s solar-system atomic model explained these propwww.pdfgrip.com erties internally—for instance, through the number of electrons in an atom’s outermost orbit For example, neon (with ten electrons) is totally inert, while sodium (with eleven) is extremely reactive Ten electrons completely fill neon’s two atomic orbits, giving the atom a “smooth” outer surface—a full orbit leaves nothing for another atom to grab It is the opposite case with sodium; its eleventh electron is alone in the atom’s otherwise empty third orbital ring Return to text *9 Diffraction gratings bend light so that it interferes with itself in classic wave form Return to text †10 Photocells (short for photoelectric cells) make up solar panels, which work by the photoelectric effect Einstein’s Noble was for his explanation of this effect by light quanta Return to text *11 In classical mythology, Scylla was a monster (later a perilous rock) standing across a narrow boating channel from the whirlpool Charybdis Return to text *12 “Mechanical” meaning “separable parts obeying causal laws.” A characteristic footnote elsewhere in the book reads, “The term ‘quantum mechanics’ is very much a misnomer It should, perhaps, be called ‘quantum non-mechanics.’” Return to text *13 When a paper is submitted to a science journal such as this one, the journal’s editor sends it out to specialists who work in the relevant field These “referees” read the article and make (anonymous) editorial recommendations (Thus the full-time editor of a journal does not have to be an expert in the thorny and often changing arcana of every field the journal covers.) Return to text *14 Because the explosion in the number of physicists after World War II resulted in a parallel explosion of physics papers, in 1958 Physical Review began publishing Physical Review Letters, an alternate venue for the “letters”—i.e., short, significant papers Return to text *15 “Analyzer” is a general name for the two pieces of experimental apparatus at either end of an EPR experiment In the versions of both Bohm and Bell, atoms with a spin of 1/2 were analyzed by Stern-Gerlach magnets, which measure whether that spin is up or down Kocher and Commins’s version did not use spin-1/2 particles, so they needed analyzers of a different nature, but the principle is the same Return to text †16 In fact, spin and polarization can, cautiously, be described as two ways of talking about the same fundamental physical situation; e.g., “spin up” in the photon’s direction of motion is the particle description of right-hand-circular polarization in a light wave (Circular polarization is the result of a complicated addition of vertical and horizontal components.) Return to text www.pdfgrip.com *17 Tantalum is a refractory metal, which means you can run it up to a very high temperature, because it’s very hard to evaporate Return to text *18 An angstrom unit (Å) is a tenth of a nanometer (a ten-billionth of a meter) Return to text *19 Capacitors are a basic component of electrical circuitry that store electric charge Return to text *20 I.e., the one that counted the longer-wavelength photon, which in this case was actually green Return to text *21 This experiment (published in Physical Review Letters for Christmas 1982) was so difficult to carry out that Aspect and his student, Jean Dalibard, listed the machinist, Gérard Roger, as an author Return to text *22 The same discovery was made simultaneously in Maryland by Yanhua Shih, in his Ph.D dissertation under Carroll Alley Return to text *23 Part of the reason for this is “the three-body problem”: a physicist can predict the path of any two “bodies” in orbit—e.g., the earth and the sun—but if he also considers a third body, like the moon, the paths are no longer perfectly predictable Return to text *24 Later published as The Character of Physical Law Return to text *25 A technical footnote: Among Dirac’s “second-class difficulties” were the infinities of quantum electrodynamics Return to text *26 But recall that “standing still” actually means moving pretty quickly as the earth rolls around the sun Return to text *27 The beam splitters send the entangled photons in opposite directions (in this case, one to Bernex and one to Bellevue) Return to text *28 Matter and antimatter emerging from the energy of a collision Return to text www.pdfgrip.com *29 “This minority view is as old as quantum mechanics itself, so the new theory may be a long time coming… We emphasize not only that our view is that of a minority, but also that current interest in such questions is small The typical physicist feels that they have long been answered, and that he will fully understand just how if ever he can spare 20 minutes to think about it.” (This is Bell’s footnote.) Return to text *30 “Who ordered that?” said I I Rabi Return to text *31 The word state is so vague that many of the founding fathers, particularly Schrödinger, complained about its use For clarity, Kramers used the term physical situation instead of state Return to text www.pdfgrip.com THIS IS A BORZOI BOOK PUBLISHED BY ALFRED A KNOPF Copyright © 2008 by Louisa Gilder All rights reserved Published in the United States by Alfred A Knopf, a division of Random House, Inc., New York, and in Canada by Random House of Canada Limited, Toronto www.aaknopf.com Knopf, Borzoi Books, and the colophon are registered trademarks of Random House, Inc Owing to limitations of space, all acknowledgments to reprint previously published material can be found on Back Matter: Permissions Library of Congress Cataloging-in-Publication Data Gilder, Louisa The age of entanglement: when quantum physics was reborn / Louisa Gilder p cm Includes bibliographical references Quantum theory I Title QC174.12.G528 2008 530.12—dc22 2008011796 eISBN: 978-0-307-27036-8 v3.0 www.pdfgrip.com ... tell the story of entanglement is to tell much of the story of quantum physics itself The story of entanglement begins near the start of the century with a suspicion of the spookiness of the quantum. .. tautology!—that quantum theory violates Instead, in quantum theory, the whole seems to be greater than the sum of its parts The recoil of one ram from the head-butt of another; the lamb trotting up to the. .. spring day The speed of the diffusion of the telltale smell of the coyote is slower and more arbitrary And, even more than the ewe’s call, the diffusion of this musk is at the mercy of the air: