Many Worlds?: Everett, Quantum Theory, & Reality

by Simon Saunders, Jonathan Barrett, Adrian Kent, David Wallace

Overview

What does realism about the quantum state imply? What follows when quantum theory is applied without restriction, if need be, to the whole universe? These are the questions which an illustrious team of philosophers and physicists debate in this volume. All the contributors are agreed on realism, and on the need, or the aspiration, for a theory that unites micro- and macroworlds, at least in principle. But the further claim argued by some is that if you allow the Schrodinger equation unrestricted application, supposing the quantum state to be something physically real, then this universe is one of countlessly many others, constantly branching in time, all of which are real. The result is the many worlds theory, also known as the Everett interpretation of quantum mechanics.
The contrary claim sees this picture of many worlds as in no sense inherent in quantum mechanics, even when the latter is allowed unrestricted scope and even given that the quantum state itself is something physically real. For this picture of branching worlds fails to make physical sense, let alone common sense, even on its own terms. The status of these worlds, what they are made of, is never adequately explained. Ordinary ideas about time and identity over time become hopelessly compromised. The concept of probability itself is brought into question. This picture of many branching worlds is inchoate, it is a vision, an error. There are realist alternatives to many worlds, some even that preserve the Schrodinger equation unchanged.
Twenty specially written essays, accompanied by commentaries and discussions, examine these claims and counterclaims in depth. They focus first on the question of ontology, the existence of worlds (Part 1 and 2), second on the interpretation of probability (Parts 3 and 4), and third on alternatives or additions to many worlds (Parts 5 and 6). The introduction offers a helpful guide to the arguments for the Everett interpretation, particularly as they have been formulated in the last two decades.

Product Details

ISBN-13:	9780199655502
Publisher:	Oxford University Press
Publication date:	07/26/2012
Edition description:	Reprint
Pages:	636
Product dimensions:	6.10(w) x 9.10(h) x 1.40(d)

About the Author

Simon Saunders is Professor of Philosophy at the University of Oxford.

Jon Barrett is a Research Fellow in the Physics Department at the University of Bristol.

Adrian Kent is a Reader in Quantum Physics at the University of Cambridge.

David Wallace is a lecturer in Philosophy of Physics at the University of Oxford.

Table of Contents

Many Worlds: an Introduction, Simon Saunders1. Why Many Worlds?1. Decoherence and Ontology, David Wallace2. Quasiclassical Realms, Jim Hartle3. Macroscopic Superpositions, Decoherent Histories, and the Emergence of Hydrodynamical Behaviour, Jonathan Halliwell2. Problems with Ontology4. Can the world be only wavefunction?, Tim Maudlin5. A metaphysician looks at the Everett interpretation, John HawthorneCommentary. Reply to Hawthorne: Physics Before Metaphysics, James LadymanTranscript 1: ontology3. Probability in the Everett Interpretation6. Chance in the Everett interpretation, Simon Saunders7. A Scandal of Probability Theory, David Papineau8. How to prove the Born rule, David Wallace9. Everett and Evidence, Hilary Greaves and Wayne Myrvold4. Critical Replies10. One World versus Many: the Inadequacy of Everettian Accounts of Evolution, Probability, and Scientific Confirmation, Adrian Kent11. Probability in the Everett picture, David Albert12. Decisions, Decisions, Decisions: Can Savage Salvage Everettian Probability?, Huw PriceTranscript 2: Probability5. Alternatives to Many Worlds13. Decoherence, Einselection, Envariance, and Quantum Darwinism: From Relative States to the Existential Interpretation, Wojciech Zurek14. Two dogmas about quantum mechanics, Jeffrey Bub and Itamar PitowskyCommentary: Rabid Dogma? Comments on Bub and Pitowsky, Christopher Timpson15. The Principal Principle and Probability in the Many-Worlds interpretation, Rudiger Schack16. Pilot-wave theory: many worlds in denial?, Antony ValentiniCommentary: Reply to Valentini, Harvey Brown6. Not Only Many Worlds17. Everett and Wheeler, the Untold Story, Peter Byrne18. Apart from universes, David Deutsch19. Many Worlds in Context, Max Tegmark20. Time Symmetry and the Many-Worlds Interpretation, Lev VaidmanTranscript 3: Not (only) many worldsBibliography