Einstein's Unfinished Revolution

by Lee Smolin

  Shortly after receiving my PhD, I met Julian Barbour, who introduced me to Leibniz and Mach, and has been my mentor and guide to relational philosophy since. My philosophical education has continued through conversations with David Albert, Harvey Brown, Jim Brown, Jeremy Butterfield, Jenann Ismael, and Steve Weinstein, among many. Henrique Gomes, Simon Saunders, Roderich Tumulka, Antony Valentini, and David Wallace have been especially helpful reading and commenting on drafts and patiently explaining what I got wrong. All errors that remain are, however, my responsibility.

  Then I want very much to thank those who have become friends through our shared work on foundational problems: Stephon Alexander, Giovanni Amelino-Camelia, Abhay Ashtekar, Eli Cohen, Marina Cortês, Louis Crane, John Dell, Avshalom Elitzur, Laurent Freidel, Sabine Hossenfelder, Ted Jacobson, Stuart Kauffman, Jurek Kowalski-Glikman, Andrew Liddle, Renate Loll, João Magueijo, Roberto Mangabeira Unger, Fotini Markopoulou, and Carlo Rovelli.

  The book has been very much improved by feedback from Krista Blake, Saint Clair Cemin, Dina Graser, Jaron Lanier, and Donna Moylan. I also want to thank Kaća Bradonjić for the illustrations and for many wise and helpful suggestions on the text.

  For helpful conversations and correspondence on specific points, I must thank Jim Baggott, Julian Barbour, Freeman Dyson, Olival Freire, Stuart Kauffman, Michael Nielsen, Philip Pearle, Bill Poirier, Carlo Rovelli, and John Stachel. Alexander Blum and Jürgen Renn helped me tell a true story of the history of quantum mechanics.

  I am extremely grateful to be part of a vibrant community at the Perimeter Institute for Theoretical Physics focused on foundational physics, which gives me a home and a context for my work. In addition to those already named, I’ve learned immeasurably over the years from Gemma De las Cuevas, Bianca Dittrich, Fay Dowker, Chris Fuchs, Lucien Hardy, Adrian Kent, Rafael Sorkin, Rob Spekkens, and many others. I wish to thank Mike Lazaridis, Howard Burton, and Neil Turok for including me in this adventure of a lifetime, and also give a shout-out to Michael Duschenes and the whole PI staff for their intelligent and dedicated work.

  I am grateful to several classes of students, going back to “Nature Loves to Hide” at Hampshire College, who have taken various versions of a quantum physics for poets class, during which I tested the pedagogical strategies I use here. Most recently, Camilla Singh allowed herself to be a test case in an experiment to teach quantum mechanics to artists.

  John Brockman, Katinka Matson, and Max Brockman have been my literary agents and friends for the many years I have been writing books. Scott Moyers, Christopher Richards, and Thomas Penn have been great editors, and I am especially grateful to them for insisting that I could write a better book than I knew. I am proud to be among the many writers who have benefited from the critical eye of Louise Dennys.

  Finally, I owe everything to Dina Graser and Kai Smolin, who have supported me throughout all the ups and downs of this project.

  NOTES

  Preface

  1. J. S. Bell, “On the Einstein Podolsky Rosen Paradox,” Physics 1, no. 3 (November 1964): 195–200.

  Chapter 1: Nature Loves to Hide

  Epigraph Albert Einstein, “A Reply to Criticisms,” Albert Einstein: Philosopher-Scientist, ed. P. A. Schillp, 3rd ed. (Peru, IL: Open Court Publishing, 1988).

  1. Einstein to Max Born, December 4, 1926, in The Born-Einstein Letters: The Correspondence Between Albert Einstein and Max and Hedwig Born, 1916–1955, with Commentaries by Max Born, trans. Irene Born (New York: Walker and Co., 1971) 88.

  Chapter 2: Quanta

  1. Tom Stoppard, Arcadia: A Play, first performance, Royal National Theatre, London, April 13, 1993; act 1, scene 1 (New York: Farrar, Straus and Giroux, 2008), 9.

  Chapter 4: How Quanta Share

  Epigraph John Archibald Wheeler, Quantum Theory and Measurement, ed. J. A. Wheeler and W. H. Zurek (Princeton: Princeton University Press, 1983): 194.

  1. Albert Einstein, Boris Podolsky, and Nathan Rosen, “Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?,” Physical Review 47, no. 10 (May 15, 1935): 777–80.

  2. Alain Aspect, Philippe Grangier, and Gérard Roger, “Experimental Tests of Realistic Local Theories via Bell’s Theorem,” Physical Review Letters 47, no. 7 (August 1981): 460–63; Alain Aspect, Jean Dalibard, and Gérard Roger, “Experimental Test of Bell’s Inequalities Using Time-Varying Analyzers,” Physical Review Letters 49, no. 25 (December 1982): 1804–7.

  3. Niels Bohr, “Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?,” Physical Review 48, no. 8 (October 1935): 696–702.

  4. Simon Kochen and E. P. Specker, “The Problem of Hidden Variables in Quantum Mechanics,” Journal of Mathematics and Mechanics 17, no. 1 (July 1967): 59–87; John S. Bell, “On the Problem of Hidden Variables in Quantum Mechanics,” Reviews of Modern Physics 38, no. 3 (July 1966): 447–52.

  Chapter 6: The Triumph of Anti-Realism

  Epigraph Christopher A. Fuchs and Asher Peres, “Quantum Theory Needs No ‘Interpretation,’” Physics Today 53, no. 3 (March 2000): 70–71, https://doi.org/10.1063/1.883004.

  1. J. J. O’Connor and E. F. Robertson, “Louis Victor Pierre Raymond duc de Broglie,” http://www-history.mcs.st-andrews.ac.uk/Biographies/Broglie.html.

  2. Louis de Broglie, interview by Thomas S. Kuhn, Andre George, and Theo Kahan, January 7, 1963, transcript, Niels Bohr Library & Archives, American Institute of Physics, College Park, MD, https://repository.aip.org/islandora/object/nbla:272502.

  3. Werner Heisenberg, The Physicist’s Conception of Nature, trans. Arnold J. Pomerans (New York: Harcourt Brace, 1958), 15, 29.

  4. Niels Bohr (1934), quoted in Max Jammer, The Philosophy of Quantum Mechanics: The Interpretations of Quantum Mechanics in Historical Perspective (New York: John Wiley and Sons, 1974), 102.

  Chapter 7: The Challenge of Realism: de Broglie and Einstein

  1. Guido Bacciagaluppi and Antony Valentini, Quantum Theory at the Crossroads: Reconsidering the 1927 Solvay Conference (Cambridge, UK: Cambridge University Press, 2009), 235.

  2. Bacciagaluppi and Valentini, 487.

  3. Grete Hermann, “Die naturphilosophischen Grundlagen der Quantenmechanik,” Die Naturwissenschaften 23, no. 42 (October 1935), 718–21, doi:10.1007/BF01491142; Grete Hermann, “The Foundations of Quantum Mechanics in the Philosophy of Nature,” trans. with an introduction by Dirk Lumma, The Harvard Review of Philosophy 7, no. 1 (1999): 35–44.

  4. John Bell, “Interview: John Bell,” interview by Charles Mann and Robert Crease, Omni 10, no. 8 (May 1988): 88.

  5. N. David Mermin, “Hidden Variables and the Two Theorems of John Bell,” Reviews of Modern Physics 65, no. 3 (July 1993): 805–6.

  Chapter 8: Bohm: Realism Tries Again

  Epigraph Roderich Tumulka, “On Bohmian Mechanics, Particle Creation, and Relativistic Space-Time: Happy 100th Birthday, David Bohm!,” Entropy 20, no. 6 (June 2018): 462, arXiv:1804.08853v3.

  1. David Bohm, “A Suggested Interpretation of Quantum Theory in Terms of ‘Hidden’ Variables, 1,” Physical Review 85, no. 2 (January 1952): 166–79.

  2. Albert Einstein, quoted in Wayne Myrvold, “On Some Early Objections to Bohm’s Theory,” International Studies in the Philosophy of Science 17, no. 1 (March 2003): 7–24.

  3. Albert Einstein, quoted in E. David Peat, Infinite Potential: The Life and Times of David Bohm (New York: Basic Books, 1997), 132.

  4. Albert Einstein, “Elementäre Überlegungen zur Interpretation der Grundlagen der Quanten-Mechanik,” in Scientific Papers Presented to Max Born (New York: Hafner, 1953), 33–40; quoted in Myrvold.

  5. Benyamin Cohen, “4 Things Einstein Said to Cheer Up His Sad Friend,” From the Grapevine, June 13, 2017, https://www.fromthegrapevine.com/lifestyle/einstein-bohm-letters-winner-auction-israel.

  6. Werner Heisenberg, quoted in Myrvold, “On Some Early Objections,” 12.

 
7. Olival Freire Jr., “Science and Exile: David Bohm, the Hot Times of the Cold War, and His Struggle for a New Interpretation of Quantum Mechanics,” Historical Studies on the Physical and Biological Sciences 36, no. 1 (September 2005): 1–34, https://arxiv.org/pdf/physics/0508184.pdf.

  8. J. Robert Oppenheimer remarks to Max Dresden, in Max Dresden, H. A. Kramers: Between Tradition and Revolution (New York: Springer-Verlag, 1987), 133. Also quoted in F. David Peat’s Infinite Potential: The Life and Times of David Bohm (Reading, MA: Addison-Wesley, 1996), where he attributes them to Dresden’s “remarks from the floor at the American Physical Society Meeting, Washington, May, 1989. Dresden confirmed this version in an interview with the author [Peat] immediately following that session and in a letter to the author.” (Quote, p. 133; note, p. 334.)

  9. Peat, Infinite Potential, 133.

  10. John Nash to J. Robert Oppenheimer, July 10, 1957, Institute for Advanced Study, Shelby White and Leon Levy Archives Center, https://www.ias.edu/ideas/2015/john-forbes-nash-jr.

  11. Léon Rosenfeld to David Bohm, May 30, 1952, quoted in Louisa Gilder, The Age of Entanglement: When Quantum Physics Was Reborn (New York: Alfred A. Knopf, 2008), 216–17.

  12. Antony Valentini, “Signal-Locality, Uncertainty, and the Sub-Quantum H-Theorem, 1,” Physics Letters A 156, nos. 1–2 (June 1991): 5–11; “2,” Physics Letters A 158, nos. 1–2 (August 1991): 1–8.

  13. Antony Valentini and Hans Westman, “Dynamical Origin of Quantum Probabilities,” Proceedings of the Royal Society of London A 461, no. 2053 (January 2005): 253–72, arXiv:quant-ph/0403034; Eitan Abraham, Samuel Colin, and Antony Valentini, “Long-Time Relaxation in Pilot-Wave Theory,” Journal of Physics A: Mathematical and Theoretical 47, no. 39 (September 2014): 5306, arXiv:1310.1899.

  14. Antony Valentini, “Signal-Locality in Hidden-Variables Theories,” Physics Letters A 297, nos. 5–6 (May 2002): 273–78.

  15. Nicolas G. Underwood and Antony Valentini, “Anomalous Spectral Lines and Relic Quantum Nonequilibrium” (2016), arXiv:1609.04576; Samuel Colin and Antony Valentini, “Robust Predictions for the Large-Scale Cosmological Power Deficit from Primordial Quantum Nonequilibrium,” International Journal of Modern Physics D25, no. 6 (April 2016): 1650068, arXiv:1510.03508.

  Chapter 9: The Collapse of the Quantum State

  1. David Bohm and Jeffrey Bub, “A Proposed Solution of the Measurement Problem in Quantum Mechanics by a Hidden Variable Theory,” Reviews of Modern Physics 38, no. 3 (July 1966): 453–69.

  2. Philip Pearle, “Reduction of the State Vector by a Nonlinear Schrödinger Equation,” Physical Review D 13, no. 4 (February 1976): 857–68.

  3. Giancarlo Ghirardi, Alberto Rimini, and Tullio Weber, “Unified Dynamics for Microscopic and Macroscopic Systems,” Physical Review D 34, no. 2 (July 1986): 470–91.

  4. Roderich Tumulka, “A Relativistic Version of the Ghirardi-Rimini-Weber Model,” Journal of Statistical Physics 125, no. 4 (November 2006): 821–40.

  5. Roger Penrose, “Gravitational Collapse and Space-Time Singularities,” Physical Review Letters 14, no. 3 (January 1965): 57–59.

  6. Stephen W. Hawking and Roger Penrose, “The Singularities of Gravitational Collapse and Cosmology,” Proceedings of the Royal Society A 314, no. 1519 (January 1970): 529–48.

  7. R. Penrose, “Time-Asymmetry and Quantum Gravity,” in Quantum Gravity 2: A Second Oxford Symposium, eds. C. J. Isham, R. Penrose, and D. W. Sciama (Oxford: Clarendon Press, 1981), 244; R. Penrose, “Gravity and State Vector Reduction,” in Quantum Concepts in Space and Time, eds. R. Penrose and C. J. Isham (Oxford: Clarendon Press, 1986), 129; R. Penrose, “Non-locality and Objectivity in Quantum State Reduction,” in Quantum Coherence and Reality: In Celebration of the 60th Birthday of Yakir Aharonov, eds. J. S. Anandan and J. L. Safko (Singapore: World Scientific, 1995), 238; R. Penrose, Shadows of the Mind: A Search for the Missing Science of Consciousness (Oxford: Oxford University Press, 1994); R. Penrose, “On Gravity’s Role in Quantum State Reduction,” General Relativity and Gravitation 28, no. 5 (May 1996): 581–600; I. Fuentes and R. Penrose, “Quantum State Reduction via Gravity, and Possible Tests Using Bose-Einstein Condensates,” in Collapse of the Wave Function: Models, Ontology, Origin, and Implications, ed. S. Gao (Cambridge, UK: Cambridge University Press, 2018), 187.

  8. L. Diósi, “Models for Universal Reduction of Macroscopic Quantum Fluctuations,” Physical Review A 40, no. 3 (August 1989): 1165–74; F. Károlyházy, “Gravitation and Quantum Mechanics of Macroscopic Bodies,” Il Nuovo Cimento A 42, no. 2 (March 1966): 390–402; F. Károlyházy, A. Frenkel, and B. Lukács, “On the Possible Role of Gravity in the Reduction of the Wave Function,” in Quantum Concepts in Space and Time, 109–28.

  9. S. Bose, A. Mazumdar, G. W. Morley, H. Ulbricht, M. Toros, M. Paternostro, A. A. Geraci, P. F. Barker, M. S. Kim, and G. Milburn, “Spin Entanglement Witness for Quantum Gravity,” Physical Review Letters 119, no. 24 (December 2017): 240401, arXiv:1707.06050; C. Marletto and V. Vedral, “Gravitationally Induced Entanglement between Two Massive Particles Is Sufficient Evidence of Quantum Effects in Gravity,” Physical Review Letters 119, no. 24 (December 2017): 240402, arXiv:1804.11315.

  10. Philip Pearle, “A Relativistic Dynamical Collapse Model,” Physical Review D 91, no. 10 (May 2015): 105012, arXiv:1412.6723.

  11. Rodolfo Gambini and Jorge Pullin, “The Montevideo Interpretation of Quantum Mechanics: A Short Review,” Entropy 20, no. 6 (February 2015): 413, arXiv:1502.03410.

  12. Stephen L. Adler, “Gravitation and the Noise Needed in Objective Reduction Modes,” in Quantum Nonlocality and Reality: 50 Years of Bell’s Theorem, eds. Mary Bell and Shan Gao (Cambridge, UK: Cambridge University Press, 2016), 390–99.

  Chapter 10: Magical Realism

  Epigraph Bryce S. DeWitt, “Quantum Mechanics and Reality: Could the Solution to the Dilemma of Indeterminism Be a Universe in Which All Possible Outcomes of an Experiment Actually Occur?” Physics Today 23, no. 9 (September 1970): 155–65.

  1. Hugh Everett III, “‘Relative State’ Formulation of Quantum Mechanics,” Reviews of Modern Physics 29, no. 3 (July 1957): 454–62.

  Chapter 11: Critical Realism

  1. David Deutsch, “Quantum Theory of Probability and Decisions,” Proceedings of the Royal Society A 455, no. 1988 (August 1999): 3129–37, arXiv:quant-ph/9906015.

  2. David Wallace, “Quantum Probability and Decision Theory, Revisited” (2002), arXiv:quant-ph/0211104; Wallace, “Everettian Rationality: Defending Deutsch’s Approach to Probability in the Everett Interpretation,” Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics 34, no. 3 (September 2003): 415–39, arXiv:quant-ph/0303050; Wallace, “Quantum Probability from Subjective Likelihood: Improving on Deutsch’s Proof of the Probability Rule,” Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics 38, no. 2 (June 2007): 311–32, arXiv:quant-ph/0312157; Wallace, “A Formal Proof of the Born Rule from Decision-Theoretic Assumptions” (2009), arXiv:quant-ph/0906.2718; Simon Saunders, “Derivation of the Born Rule from Operational Assumptions,” Proceedings of the Royal Society A 460, no. 2046 (June 2004): 1771–88, arXiv:quant-ph/0211138.

  3. Lawrence S. Schulman, “Note on the Quantum Recurrence Theorem,” Physical Review A 18, no. 5 (November 1978): 2379–80, doi:10.1103/PhysRevA.18.2379.

  4. Steven Weinberg, “The Trouble with Quantum Mechanics,” The New York Review of Books, January 19, 2017, https://www.nybooks.com/articles/2017/01/19/trouble-with-quantum-mechanics/.

  Chapter 12: Alternatives to Revolution

  Epigraph Lucien Hardy, “Reformulating and Reconstructing Quantum Theory” (2011), arXiv:1104.2066.

  1. Richard Feynman, “Simulating Physics with Computers,” keynote address delivered at the MIT Physics of Computation Conference, 1981. Published in International Journal of Theoretical Physics 21, nos. 6–7 (June 1982):
467–88.

  2. David Deutsch, “Quantum Theory, the Church-Turing Principle and the Universal Quantum Computer,” Proceedings of the Royal Society A 400, no. 1818 (July 1985): 97–117.

  3. John Archibald Wheeler, “Information, Physics, Quantum: The Search for Links,” in Proceedings of the 3rd International Symposium: Foundations of Quantum Mechanics in the Light of New Technology, Tokyo, 1989, eds. Shunichi Kobayashi et al. (Tokyo: Physical Society of Japan, 1990), 354–58.

  4. John Archibald Wheeler, quoted in Paul Davies, The Goldilocks Enigma, also titled Cosmic Jackpot (Boston and New York: Houghton Mifflin, 2006), 281.

  5. Christopher A. Fuchs and Blake C. Stacey, “QBism: Quantum Theory as a Hero’s Handbook” (2016), arXiv:1612.07308.

  6. Louis Crane, “Clock and Category: Is Quantum Gravity Algebraic?,” Journal of Mathematical Physics 36, no. 11 (May 1995): 6180–93, arXiv:gr-qc/9504038; Carlo Rovelli, “Relational Quantum Mechanics,” International Journal of Theoretical Physics 35, no. 8 (August 1996): 1637–78, arXiv:quant-ph/9609002; Lee Smolin, “The Bekenstein Bound, Topological Quantum Field Theory and Pluralistic Quantum Cosmology” (1995), arXiv:gr-qc/9508064.

  7. Ruth E. Kastner, Stuart Kauffman, and Michael Epperson, “Taking Heisenberg’s Potentia Seriously” (2017), arXiv:1709.03595.

  8. Julian Barbour, The End of Time: The Next Revolution in Physics (Oxford: Oxford University Press, 1999).

  9. Henrique de A. Gomes, “Back to Parmenides” (2016, 2018), arXiv:1603.01574.

  Chapter 13: Lessons

  1. I am grateful to Avshalom Elitzur and Eli Cohen for many discussions on these kinds of cases.

  2. For a recent review, see Roderich Tumulka, “Bohmian Mechanics,” in The Routledge Companion to the Philosophy of Physics, eds. Eleanor Knox and Alastair Wilson (New York: Routledge, 2018), arXiv:/1704.08017.