I conclude with some additional comments that have mostly already appeared in the UK paperback.
My website now carries an email dialogue between myself and Don Page (whom Hawking, in A Brief History of Time, credits with pointing out, with Raymond Laflamme, ‘his greatest blunder’). I think Don has made some interesting and valuable comments, including both valid criticism of some points but also reassurance on other issues on which I had doubts. Don is another person who takes the timelessness of physics utterly seriously, and, in fact, our views are very close. He has written several papers on the problem of consciousness and quantum mechanics (Sensible Quantum Mechanics). Full details can be found on my website. I should also like to mention here an idea that Dieter Zeh put forward in the meeting at Huelva in Spain at which I conducted my straw poll. This is that the universe must, of necessity, always be observed as expanding. I find this an intriguing idea and, if it is correct, it would fit beautifully with the open-ended, flowerlike structure of Platonia. I think Dieter’s idea, which I hope is correct though I have hedged my bets in this book, influenced me somewhat in the writing of Box 3 and parts of the Epilogue.
I regret that in the final chapter I made no mention of the idea of inflation, which is explained in a gripping and candid book by Alan Guth that I have at least now included in the books recommended for further reading. From reading Guth’s book I also learned that an interesting proposal of a mechanism for the ‘creation of the universe’ was made by Edward Tryon in 1973. I should also have mentioned that in 1982 Alexander Vilenkin proposed an influential alternative proposal to Hawking’s no-boundary idea (1981) and that Jim Hartle played a significant role in its development, which culminated the Hartle-Hawking wave function. My apologies to these authors (none of whom have registered any complaint). Details can be found in Guth’s book.
It has also been pointed out to me by several email correspondents that there is a clear anticipation of some of my ideas about time in Fred Hoyle’s novel October the First Is Too Late, which Paul Davies discusses in his About Time. Sir Fred’s ‘pigeonholes’ are essentially my time capsules. American reviewers and correspondents also noted a similarity with the philosophy of time that underlies Kurt Vonnegut’s Slaughterhouse Five. Having now read the book, I can confirm that this is the case. Of course, as I make clear in the text, John Bell also formulated the idea of time capsules (without giving them any name) quite clearly long before me. Another correspondent, Andrew Clifton, regretted that I had not devoted at least a few words to demolishing the idea that there really is a ‘moving present’. I think he was right. Happily, David Deutsch has done the job very well in his The Fabric of Reality.
I should also like to thank Damien Broderick, who has reviewed my book for The Australian, for drawing my attention to various misprints.
It is also now clear to me that in the body of the text I should have said more about possible ways in which my ideas could be refuted. A theory is no use to science unless it is capable of disproof. In the email exchange with Fay Dowker, I did mention the possibility of mathematical disproof of my conjecture that the Wheeler—DeWitt equation concentrates its solutions on time capsules. However, I think that (in normal parlance) that might take decades. Something that might occur much sooner is a completely convincing definitive form of superstring theory (or some other unified theory) that reintroduces an external time (string theory does currently use background structures). That would kill my idea. My own feeling is that in fact superstring theory will, if and when it is found, turn out to be timeless.
Then there is one other quite different way in which my ideas could be disproved. This is if experimental evidence can be found that shows collapse of the quantum wave function to be a real physical process. In this connection, I should like to mention especially an experiment proposed by Roger Penrose to test this very possibility. He is developing it in collaboration with Anton Zeilinger, the Austrian physicist based in Vienna, who has performed so many incredibly beautiful quantum experiments. Penrose, very understandably, finds the many-worlds interpretation of quantum mechanics extremely hard to accept (see my comments about the death of Diana), and with great persistence is trying to find a way round it. He has certainly identified the greatest single issue in modern physics. If his experiment, which could perhaps be performed within a decade, works out in the way he hopes, it will be a huge development and destroy my approach (because it will show that quantum mechanics does not hold macroscopically). The volume containing my paper (Barbour 2000) also contains Penrose’s most important paper on the subject, and also a related paper by Joy Christian, who was a student of Abner Shimony. Joy, following Abner (see my Epilogue), is trying to establish transience as a real physical thing. I think that if collapse of the wave function could be demonstrated as a real physical phenomenon, that would be true demonstration of something that one might call transience.
JB
January 2001
FURTHER READING
Barrow, John, 1992, Theories of Everything, Oxford University Press, Oxford.
Barrow, John and Tipler, Frank, 1986, The Anthropic Cosmological Anthropic Principle, Clarendon Press, Oxford.
Bondi, Hermann, 1962, Relativity and Common Sense: A New Approach to Einstein, Dover, New York.
Coleman, James, 1954, Relativity for the Layman, William-Frederick Press, New York (1990, Penguin, London).
Coveney, Peter and Highfield, Roger, 1991, The Arrow of Time, Flamingo, London.
Davies, Paul, 1991, The Mind of God, Simon & Schuster, New York.
Davies, Paul, 1995, About Time: Einstein’s Unfinished Revolution, Penguin Press, London.
Deutsch, David, 1997, The Fabric of Reality, Penguin Press, London.
Eddington, Arthur, 1920, Space, Time and Gravitation, Cambridge University Press, Cambridge.
Einstein, Albert, 1960, Relativity: The Special and the General Theory. A Popular Exposition, Routledge, London.
Greene, Brian, 1999, The Elegant Universe: Superstrings, Hidden Dimensions, and the Quest for the Ultimate Theory, Vintage Books, New York.
Gribbin, John, 1984, In Search of Schrödinger’s Cat: Quantum Physics and Reality, Corgi, London.
Guth, Alan H., 1997, The Inflationary Universe: The Quest for a New Theory of Cosmic Origins, Perseus Books Group, New York.
Lippincott, Kristen, Eco, Umberto, Gombrich, E. H. et al., 1999, The Story of Time, Merrell Holberton, London. [This is a splendid book on the most diverse aspects of time in culture and science.]
Lockwood, Michael, 1989, Mind, Brain and the Quantum, Basil Blackwell, Oxford.
Novikov, Igor, 1998, The River of Time, Cambridge University Press, Cambridge.