Many Worlds?

Everett, Quantum Theory, & Reality

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

The first full appraisal of one of the most startling theories in modern science
Debates crucial questions about how we understand the universe
Featuring a stellar line-up of philosophers and physicists

Many Worlds?

Everett, Quantum Theory, & Reality

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

Description

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.

Many Worlds?

Everett, Quantum Theory, & Reality

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

Many Worlds: an Introduction, Simon Saunders
1. Why Many Worlds?
1. Decoherence and Ontology, David Wallace
2. Quasiclassical Realms, Jim Hartle
3. Macroscopic Superpositions, Decoherent Histories, and the Emergence of Hydrodynamical Behaviour, Jonathan Halliwell
2. Problems with Ontology
4. Can the world be only wavefunction?, Tim Maudlin
5. A metaphysician looks at the Everett interpretation, John Hawthorne
Commentary. Reply to Hawthorne: Physics Before Metaphysics, James Ladyman
Transcript 1: ontology
3. Probability in the Everett Interpretation
6. Chance in the Everett interpretation, Simon Saunders
7. A Scandal of Probability Theory, David Papineau
8. How to prove the Born rule, David Wallace
9. Everett and Evidence, Hilary Greaves and Wayne Myrvold
4. Critical Replies
10. One World versus Many: the Inadequacy of Everettian Accounts of Evolution, Probability, and Scientific Confirmation, Adrian Kent
11. Probability in the Everett picture, David Albert
12. Decisions, Decisions, Decisions: Can Savage Salvage Everettian Probability?, Huw Price
Transcript 2: Probability
5. Alternatives to Many Worlds
13. Decoherence, Einselection, Envariance, and Quantum Darwinism: From Relative States to the Existential Interpretation, Wojciech Zurek
14. Two dogmas about quantum mechanics, Jeffrey Bub and Itamar Pitowsky
Commentary: Rabid Dogma? Comments on Bub and Pitowsky, Christopher Timpson
15. The Principal Principle and Probability in the Many-Worlds interpretation, Rudiger Schack
16. Pilot-wave theory: many worlds in denial?, Antony Valentini
Commentary: Reply to Valentini, Harvey Brown
6. Not Only Many Worlds
17. Everett and Wheeler, the Untold Story, Peter Byrne
18. Apart from universes, David Deutsch
19. Many Worlds in Context, Max Tegmark
20. Time Symmetry and the Many-Worlds Interpretation, Lev Vaidman
Transcript 3: Not (only) many worlds
Bibliography

Many Worlds?

Everett, Quantum Theory, & Reality

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

Author Information

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.

Contributors:

David Albert, Columbia University in New York
Harvey Brown, University of Oxford
Jeffrey Bub, University of Maryland
Peter Byrne
David Deutsch, University of Oxford
Hilary Greaves, University of Oxford
Jonathan Halliwell, Imperial College, London
Jim Hartle, University of California, Santa Barbara
John Hawthorne, University of Oxford
Adrian Kent, University of Cambridge
James Ladyman, University of Bristol
Tim Maudlin, Rutgers University
Wayne Myrvold, University of Western Ontario
David Papineau, King's College London
Itamar Pitowsky, The Hebrew University
Huw Price, University of Sydney
Simon Saunders, University of Oxford
Rudiger Schack, University of Royal Holloway, London
Max Tegmark, Massachusetts Institute of Technology
Christopher Timpson, University of Oxford
Lev Vaidman, Tel Aviv University
Antony Valentini, Imperial College, London
David Wallace, University of Oxford
Wojciech Zurek, Los Alamos National Laboratory