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Many Worlds?: Everett, Quantum Theory, & Reality
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.
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.
- GenresPhysicsPhilosophyScience
636 pages, Hardcover
First published June 1, 2010
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Displaying 1 - 3 of 3 reviews
February 17, 2016
This book is a collection of diverse essays by leading philosophers of science, metaphysicians, and physicists dealing with Everett's interpretation of quantum mechanics (QM). It is not an easy read, though some essays are easier than others, but it does address several important issues in the philosophy of quantum physics.
For the most part the contributors are sympathetic to the Everettian "many worlds" interpretation of QM. There are a few exceptions, most notably Tim Maudlin's and John Hawthorne's essays on ontology and metaphysics, respectively.
Two issues that are dealt with multiple times throughout are the "problem" of "preferred basis" for the understanding of measurement in Everett and the more recent concept of decoherence, which is itself partly a solution to the problem of preferred basis.
The issues and various perspectives in this book are too complex and multi-sided to summarize in this setting. The book is worth reading for anyone interested in metaphysics on the one hand (my personal reason for reading) or interested in Everett's interpretation of QM. Physicists would benefit from serious engagement with the philosophers and metaphysicians, and vice versa. A difficult but worthwhile read.
For the most part the contributors are sympathetic to the Everettian "many worlds" interpretation of QM. There are a few exceptions, most notably Tim Maudlin's and John Hawthorne's essays on ontology and metaphysics, respectively.
Two issues that are dealt with multiple times throughout are the "problem" of "preferred basis" for the understanding of measurement in Everett and the more recent concept of decoherence, which is itself partly a solution to the problem of preferred basis.
The issues and various perspectives in this book are too complex and multi-sided to summarize in this setting. The book is worth reading for anyone interested in metaphysics on the one hand (my personal reason for reading) or interested in Everett's interpretation of QM. Physicists would benefit from serious engagement with the philosophers and metaphysicians, and vice versa. A difficult but worthwhile read.
December 8, 2024
Many-Worlds interpretation of quantum mechanics is very much like a contemporary Plato's cave, as in both cases what people look at are projections rather than real things. As Wallace argues in this volume, there is a sense in which the existence of real things may be recovered from the inherent structure of the quantum world, but if anything, structures are emphatically not a part of the formalism, the definition and classification of structures must be postulated. The famous retort that Many-Worlds envisions a rather extravagant parsimony turns out to be true not only in the number of worlds, but also in the number of extra metaphysical postulates in addition to the formalism. The cost for a simpler physical theory seems to be a much more complex metaphysical theory, perhaps this is a new meta uncertainty principle. In any case, as much as this volume is praised as a modern classic, no one actually cares, nor should anyone. The only significant achievement of this book is probably that it serves as a definite proof that Humeanism is at best a complete waste of time, and at worst, a spectacular scam.
December 9, 2018
This was too technical for me. But the parts I understood were thought provoking.
Displaying 1 - 3 of 3 reviews