by Jim Baggott
5. Karl Popper, Conjectures and Refutations: The Growth of Scientific Knowledge (Routledge & Kegan Paul, London, 1963), p. 49.
6. Lee Smolin, Time Reborn: From the Crisis in Physics to the Future of the Universe (Penguin Books, London, 2013), p. 38.
7. Albert Einstein, letter to Paul Ehrenfest, 17 January 1916, quoted in Robert E. Kennedy, A Student’s Guide to Einstein’s Major Papers (Oxford University Press, Oxford, 2012). The quote appears on p. 214.
8. Paul Feyerabend, Against Method, 3rd edition (Verso, London, 1993), pp. 52–3.
9. Larry Laudan, ‘The Demise of the Demarcation Problem’, in R. S. Cohen and L. Laudan (eds), Physics, Philosophy and Psychoanalysis (D. Riedel, Dordrecht, 1983), p. 125.
10. Massimo Pigliucci, in Massimo Pigliucci and Maarten Boudry (eds), The Philosophy of Pseudoscience: Reconsidering the Demarcation Problem (University of Chicago Press, Chicago, 2013), p. 26.
11. Popper, Conjectures and Refutations, p. 346. The italics are mine.
12. Albert Einstein, ‘On the Generalised Theory of Gravitation’, Scientific American, April 1950, p. 13.
13. Don Ross, James Ladyman, and David Spurrett, ‘In Defence of Scientism’, in Ladyman and Ross, Every Thing Must Go, pp. 33–8.
14. See, for example, Lee Smolin, The Trouble with Physics: The Rise of String Theory, the Fall of a Science, and What Comes Next (Penguin Books, London, 2008), and Jim Baggott, Farewell to Reality: How Fairy-tale Physics Betrays the Search for Scientific Truth (Constable, London, 2013).
15. Gottfried Wilhelm Leibniz, from his correspondence with Samuel Clarke (1715–16), Collected Writings, edited by G. H. R. Parkinson (J. M. Dent & Sons, London, 1973), p. 226.
16. Isaac Newton, Mathematical Principles of Natural Philosophy, first American edition, translated by Andrew Motte (Daniel Adee, New York, 1845), p. 73.
17. Ernst Mach, The Science of Mechanics: A Critical and Historical Account of Its Development, 4th edition, translated by Thomas J. McCormack (Open Court Publishing, Chicago, 1919), p. 194.
18. Albert Einstein, ‘Does the Inertia of a Body Depend on its Energy Content?’, Annalen der Physik, 18 (1905), 639–41. This paper is translated and reproduced in John Stachel (ed.), Einstein’s Miraculous Year: Five Papers That Changed the Face of Physics, centenary edition (Princeton University Press, Princeton, NJ, 2005). The quote appears on p. 164.
19. See my book Mass: The Quest to Understand Matter from Greek Atoms to Quantum Fields (Oxford University Press, Oxford, 2017).
20. See, for example, Richard Boyd, ‘On the Current Status of Scientific Realism’, Erkenntnis 19 (1983), 45–90. Reproduced in Richard Boyd, Philip Gaspar, and J. D. Trout (eds), The Philosophy of Science (MIT Press, Cambridge, MA, 1991), see especially p. 195.
21. Hilary Putnam, Mathematics, Matter and Method (Cambridge University Press, Cambridge, UK, 1975), p. 73. Quoted in James Ladyman, ‘Structural Realism’, Stanford Encyclopedia of Philosophy, Winter 2016, p. 6.
22. Ian Hacking, Representing and Intervening: Introductory Topics in the Philosophy of Natural Science (Cambridge University Press, Cambridge, UK, 1983), p. 31. The italics are mine.
Chapter 4: When Einstein Came Down to Breakfast
1. Niels Bohr, quoted by Aage Petersen, ‘The Philosophy of Niels Bohr’, Bulletin of the Atomic Scientists, 19 (1963), 12.
2. A careful analysis of Bohr’s philosophical influences and writings suggests that he was closer to the tradition known as pragmatism than to positivism. Pragmatism, founded by Charles Sanders Pierce, has many of the characteristics of positivism in that they both roundly reject metaphysics. There are differences, however. We can think of the positivist doctrine as one of ‘seeing is believing’: what we can know is limited by what we can observe empirically. The pragmatist doctrine admits a more practical (or, indeed, pragmatic) approach: what we can know is limited not by what we can see, but by what we can do. See, for example, Dugald Murdoch, Niels Bohr’s Philosophy of Physics (Cambridge University Press, Cambridge, UK, 1987).
3. Werner Heisenberg, The Physical Principles of the Quantum Theory (University of Chicago Press, Chicago, 1930). Republished in 1949 by Dover Publications, New York. This quote appears in the preface.
4. Max Born and Werner Heisenberg, ‘Quantum Mechanics’, Proceedings of the Fifth Solvay Congress, 1928. English translation from Guido Bacciagaluppi and Antony Valentini, Quantum Theory at the Crossroads: Reconsidering the 1927 Solvay Conference (Cambridge University Press, Cambridge, UK, 2009), p. 437.
5. Albert Einstein ‘General Discussion’, Proceedings of the Fifth Solvay Congress, 1928. English translation from Bacciagaluppi and Valentini, Quantum Theory at the Crossroads, p. 488.
6. Otto Stern, interview with Res Jost, 2 December 1961. Quoted in Abraham Pais, Subtle is the Lord: The Science and the Life of Albert Einstein (Oxford University Press, Oxford, 1982), p. 445.
7. Niels Bohr, in Paul Arthur Schilpp (ed.), ‘Discussion with Einstein on Epistemological Problems in Atomic Physics’, in Albert Einstein. Philosopher-scientist, The Library of Living Philosophers, Volume 1 (Harper & Row, New York, 1959; first published 1949), p. 224.
8. Albert Einstein, quoted by Hendrik Casimir in a letter to Abraham Pais, 31 December 1977. Quoted in Pais, Subtle is the Lord, p. 449.
9. Albert Einstein, Boris Podolsky, and Nathan Rosen, ‘Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?’, Physical Review, 47 (1935), 777–80. This paper is reproduced in John Archibald Wheeler and Wojciech Hubert Zurek (eds), Quantum Theory and Measurement (Princeton University Press, Princeton, NJ, 1983), pp. 138–41. This quote appears on p. 138.
10. Einstein, Podolsky, and Rosen, ‘Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?’ Also Wheeler and Zurek (eds), Quantum Theory and Measurement, p. 141.
11. Léon Rosenfeld, in Stefan Rozenthal (ed.), Niels Bohr: His Life and Work as Seen by his Friends and Colleagues (North-Holland, Amsterdam, 1967), pp. 114–36. Extract reproduced in Wheeler and Zurek (eds), Quantum Theory and Measurement, pp. 137 and 142–3. This quote appears on p. 142.
12. Paul Dirac, interview with Niels Bohr, 17 November 1962, Archive for the History of Quantum Physics. Quoted in Mara Beller, Quantum Dialogue (University of Chicago Press, Chicago, 1999), p. 145.
13. Einstein, Podolsky, and Rosen, ‘Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?’. Also in Wheeler and Zurek, (eds), Quantum Theory and Measurement, p. 141.
14. Albert Einstein, letter to Erwin Schrödinger, 8 August 1935. Quoted in Arthur Fine, The Shaky Game: Einstein, Realism and the Quantum Theory, 2nd edition (University of Chicago Press, Chicago, 1996), p. 78.
15. Erwin Schrödinger, letter to Albert Einstein, 19 August 1935. Quoted ibid., pp. 82–3.
16. Wolfgang Pauli, [review of Dirac, The Principles of Quantum Mechanics], Die Naturwissenschaften, 19 (1931), 188–9, quoted in Helge Kragh, Dirac: A Scientific Biography (Cambridge University Press, Cambridge, UK, 1990), p. 79.
Chapter 5: Quantum Mechanics is Complete So Just Shut Up and Calculate
1. Erwin Schrödinger, letter to Albert Einstein, 7 June 1935. Quoted in Arthur Fine, The Shaky Game: Einstein, Realism and the Quantum Theory, 2nd edition (University of Chicago Press, Chicago, 1996), pp. 66–7.
2. Albert Einstein, letter to Erwin Schrödinger, 19 June 1935. Ibid., p. 69.
3. Karl R. Popper, Quantum Theory and the Schism in Physics (Unwin Hyman, London, 1982), pp. 99–100.
4. John Bell, quoted by Andrew Whitaker, John Stewart Bell and Twentieth-Century Physics: Vision and Integrity (Oxford University Press, Oxford, 2016), p. 57.
5. Lee Smolin, personal communication, 21 June 2017. Quoted in Jim Baggott, Quantum Space: Loop Quantum Gravity and the Search for the Structure of Space, Time, and the Universe (Oxford University Press, Oxford, 2018), p. 245. The italics are mine.
6. Carlo Rovelli, ‘Relational Quantum Mechanics’, International Journal of Theoretical Physics,
35 (1996), 1637; arXiv: quant-ph/9609002v2, 24 February 1997, p. 1.
7. Rovelli, ibid., p. 3.
8. Matteo Smerlak and Carlo Rovelli, ‘Relational EPR’, Foundations of Physics, 37 (2007), 427–45; arXiv:quant-ph/0604064v3, 4 March 2007, p. 3.
9. Carlo Rovelli, personal communication, 14 October 2018.
10. Smerlak and Rovelli, ‘Relational EPR’, arXiv:quant-ph/0604064v3, p. 5.
11. Rovelli, ‘Relational Quantum Mechanics’, arXiv: quant-ph/9609002v2, p. 4.
12. Anton Zeilinger, ‘A Foundational Principle for Quantum Mechanics’, Foundations of Physics, 29 (1999), 633.
13. See Jeffrey Bub, ‘Quantum Mechanics Is about Quantum Information’, Foundations of Physics, 35 (2005), 541–60. See also arXiv:quant-ph/0408020v2, 12 August 2004.
14. Smerlak and Rovelli, ‘Relational EPR’, arXiv:quant-ph/0604064v3, p. 5.
15. Ibid., p. 4.
16. Niels Bohr, quoted by Aage Petersen, ‘The Philosophy of Niels Bohr’, Bulletin of the Atomic Scientists, 19 (1963), 12. The italics are mine.
17. A. J. Ayer, in A. J. Ayer (ed.), Logical Positivism, Library of Philosophical Movements (Free Press of Glencoe, 1959), p. 11. The italics are mine.
18. Ludwig Wittgenstein, Tractatus Logico-Philosophicus, translated by C. K. Ogden (Kegan Paul, Trench, Trubner, London, 1922), p. 90.
19. N. David Mermin, ‘Could Feynman Have Said This?’, Physics Today, May 2004, pp. 10–11.
Chapter 6: Quantum Mechanics Is Complete But We Need to Reinterpret What it Says
1. Lucien Hardy, ‘Quantum Theory from Five Reasonable Axioms’, arXiv:quant-ph/0101012v4, 25 September 2001.
2. Giulio Chiribella, quoted by Philip Ball in ‘Quantum Theory Rebuilt from Simple Physical Principles’, Quanta, 30 August 2017.
3. Karl R. Popper, Quantum Theory and the Schism in Physics (Unwin Hyman, London, 1982), p. 72.
4. Robert Griffiths, personal communication, 5 November 2018.
5. Robert B. Griffiths, Consistent Quantum Theory (Cambridge University Press, Cambridge, UK, 2002), p. 214.
6. Robert B. Griffiths, ‘The Consistent Histories Approach to Quantum Mechanics’, Stanford Encyclopedia of Philosophy, Spring 2017, p. 3.
7. Fay Dowker and Adrian Kent, ‘On the Consistent Histories Approach to Quantum Mechanics’, Journal of Statistical Physics, 82 (1996), 1575–1646. See also arXiv:gr-qc/9412067v2, 25 January 1996.
8. Griffiths, ‘The Consistent Histories Approach to Quantum Mechanics’, p. 46.
9. Werner Heisenberg, Physics and Philosophy: The Revolution in Modern Science (Penguin, London, 1989; first published 1958), p. 46. The italics are mine.
10. Carlton M. Caves, Christopher A. Fuchs, and Rüdiger Schack, ‘Quantum Probabilities as Bayesian Probabilities’, Physical Review A, 65 (2002), 022305. See also arXiv:quant-ph/0106133v2, 14 November 2001.
11. Richard Healey, ‘Quantum-Bayesian and Pragmatist Views of Quantum Theory’, Stanford Encylopedia of Philosophy, Spring 2017, p. 9.
12. N. David Mermin, ‘Annotated Interview with a QBist in the Making’, arXiv:quant-ph/1301.6551.v1, 28 January 2013. However, Mermin interprets ‘QBism’ a little differently, preferring to acknowledge Bruno de Finetti, a pioneer of subjective probability, rather than Bayes. The ‘B’ then stands for ‘Bruno’.
13. Schack has argued that Hardy’s ‘five reasonable axioms’ can be reduced to four, by reinterpreting the first in terms of Bayesian probabilities and by modifying part of the proof. See Rüdiger Schack, ‘Quantum Theory from Four of Hardy’s Axioms’, Foundations of Physics, 33 (2003), 1461–8. See also arXiv:quant-ph/0210017v1, 2 October 2002.
14. Christopher A. Fuchs, N. David Mermin, and Rüdiger Schack, ‘An Introduction to QBism with an Application to the Locality of Quantum Mechanics’, American Journal of Physics, 82 (2014), 749–54. See also arXiv:quant-ph/1311.5253v1, 20 November 2013.
15. Mermin talks about CBism, the classical analogue of QBism. See N. David Mermin, ‘Making Better Sense of Quantum Mechanics’, arXiv:quant-ph/1809.01639v1, 5 September 2018.
16. Chrisopher A. Fuchs, ‘On Participatory Realism’, arXiv:quant-ph/1601.04360v3, 28 June 2016, p. 11.
Chapter 7: Quantum Mechanics is Incomplete So We Need to Add Some Things
1. John Bell, Journal de Physique Colloque C2, Supplement 3, 42 (1981), 41–61. Reproduced in J. S. Bell, Speakable and Unspeakable in Quantum Mechanics (Cambridge University Press, Cambridge, UK, 1987), pp. 139–58. This quote appears on p. 142.
2. Darrin W. Belousek, ‘Einstein’s 1927 Unpublished Hidden-Variable Theory: Its Background, Context and Significance’, Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics, 27 (1996), 437–61. Peter Holland takes a closer look at Einstein’s reasons for rejecting this approach in ‘What’s Wrong with Einstein’s 1927 Hidden-Variable Interpretation of Quantum Mechanics’, Foundations of Physics, 35 (2005), 177–96; arXiv:quant-ph/0401017v1, 5 January 2004.
3. ‘It should be noted that we need not go any further into the mechanism of the “hidden parameters”, since we now know that the established results of quantum mechanics can never be re-derived with their help.’ John von Neumann, Mathematical Foundations of Quantum Mechanics (Princeton University Press, Princeton, NJ, 1955), p. 324.
4. According to Basil Hiley, one of Bohm’s long-term collaborators, Bohm said of his meeting with Einstein: ‘After I finished [Quantum Theory] I felt strongly that there was something seriously wrong. Quantum theory had no place in it for an adequate notion of an individual actuality. My discussions with Einstein clarified and reinforced my opinion and encouraged me to look again.’ Quoted by Basil Hiley, personal communication to the author, 1 June 2009.
5. David Bohm, Quantum Theory (Prentice-Hall, Englewood Cliffs, NJ, 1951), p. 623.
6. D. Bohm and Y. Aharonov, ‘Discussion of Experimental Proof for the Paradox of Einstein, Rosen, and Podolsky’, Physical Review, 108 (1957), 1070.
7. John Bell, in P. C. W. Davies and J. R. Brown (eds), The Ghost in the Atom (Cambridge University Press, Cambridge, UK, 1986), p. 57.
8. John Bell, ‘Bertlmann’s Socks and the Nature of Reality’, Journal de Physique Colloque C2, Supplement 3, 42 (1981), 41–61. Reproduced in Bell, Speakable and Unspeakable in Quantum Mechanics: Collected Papers on Quantum Philosophy (Cambridge University Press, Cambridge, UK, 1987), pp. 139–58. This quote appears on p. 139.
9. This pictorial representation is based on Bernard d’Espagnat, ‘The Quantum Theory and Reality’, Scientific American, 241 (1979), 158–81. See p. 162.
10. John Bell, ‘Locality in Quantum Mechanics: Reply to Critics’, Epistemological Letters, November 1975, pp. 2–6. This paper is reproduced in Bell, Speakable and Unspeakable in Quantum Mechanics, pp. 63–6. This quote appears on p. 65.
11. Simon Kochen and E. P. Specker, ‘The Problem of Hidden Variables in Quantum Mechanics’, Journal of Mathematics and Mechanics, 17 (1967), 59–87.
12. John S. Bell, ‘On the Problem of Hidden Variables in Quantum Theory’, Reviews of Modern Physics, 38 (1966), 447–52. This paper is reproduced in Bell, Speakable and Unspeakable in Quantum Mechanics, pp. 1–13.
13. Calcite is a naturally birefringent form of calcium carbonate. It has a crystal structure which has different refractive indices along two distinct crystal planes. One offers an axis of maximum transmission for vertically polarized light and the other offers an axis of maximum transmission for horizontally polarized light. The vertical and horizontal components of either left- or right-circularly polarized light are therefore physically separated by passage through the crystal, and their intensities can be measured separately. With careful machining, a calcite crystal can transmit virtually all of the light incident on it.
14. Alain Aspect, Philippe Grangier, and Gérard Roger, ‘Experimental Tests of Realistic Local Theories via Bell’s Theorem’, Physical Review Letters, 47 (1981), 460–3. Alain Aspect, Philippe Grangier, and Gérard Roger, ‘Experimental R
ealization of Einstein–Podolsky–Rosen–Bohm Gedankenexperiment: A New Violation of Bell’s Inequalities’, Physical Review Letters, 49 (1982), 91–4.
15. Alain Aspect, Jean Dalibard, and Gérard Roger, ‘Experimental Test of Bell’s Inequalities Using Time-Varying Analyzers’, Physical Review Letters, 49 (1982), 1804–7.
16. W. Tittel, J. Brendel, N. Gisin, and H. Zbinden, ‘Long-Distance Bell-Type Tests Using Energy-Time Entangled Photons’, Physical Review A, 59 (1999), 4150–63.
17. Thomas Scheidl, Rupert Ursin, Johannes Kofler, Sven Ramelow, Xiao-Song Ma, Thomas Herbst, Lothar Ratschbacher, Alessandro Fedrizzi, Nathan K. Langford, Thomas Jennewein, and Anton Zeilinger, ‘Violation of Local Realism with Freedom of Choice’, Proceedings of the National Academy of Sciences, 107 (2010), 19708–13.
18. Dominik Rauch, Johannes Handsteiner, Armin Hochrainer, Jason Gallicchio, Andrew S. Friedman, Calvin Leung, Bo Liu, Lukas Bulla, Sebastian Ecker, Fabian Steinlechner, Rupert Ursin, Beili Hu, David Leon, Chris Benn, Adriano Ghedina, Massimo Cecconi, Alan H. Guth, David I. Kaiser, Thomas Scheidl, and Anton Zeilinger, ‘Cosmic Bell Test Using Random Measurement Settings from High-Redshift Quasars’, Physical Review Letters, 121 (2018), 080403.
19. Jian-Wei Pan, Dik Bouwmeester, Matthew Daniell, Harald Weinfurter, and Anton Zeilinger, ‘Experimental Test of Quantum Nonlocality in Three-Photon Greenburger-Horne-Zeilinger Entanglement’, Nature, 403 (2000), 515–19.
20. A. J. Leggett, ‘Nonlocal Hidden-Variable Theories and Quantum Mechanics: An Incompatibility Theorem’, Foundations of Physics, 33 (2003), 1469–93. This quote appears on pp. 1474–5.
21. Simon Gröblacher, Tomasz Paterek, Rainer Kaltenbaek, Caslav Brukner, Marek Zukowski, Markus Aspelmeyer, and Anton Zeilinger, ‘An Experimental Test of Non-local Realism’, Nature, 446 (2007), 871–5. In case you were wondering, Bell’s inequality is violated in these experiments, too.
22. Matthew F. Pusey, Jonathan Barrett, and Terry Rudolph, ‘On the Reality of the Quantum State’, Nature Physics, 8 (2012), 475–8.