Many Worlds? an Introduction Simon Saunders
Many Worlds? An Introduction Simon Saunders Introduction to Many Worlds? Everett, quantum theory, and reality, S. Saun- ders, J. Barrett, A. Kent, D. Wallace (eds.), Oxford University Press (2010). This problem of getting the interpretation proved to be rather more difficult than just working out the equation. P.A.M. Dirac Ask not if quantum mechanics is true, ask rather what the theory implies. What does realism about the quantum state imply? What follows then, when quantum theory is applied without restriction, if need be to the whole universe? This is the question this book addresses. The answers vary widely. Ac- cording to one view, `what follows' is a detailed and realistic picture of reality that provides a unified description of micro- and macroworlds. But according to another, the result is nonsense { there is no physically meaningful theory at all, or not in the sense of a realist theory, a theory supposed to give an intel- ligible picture of a reality existing independently of our thoughts and beliefs. According to the latter view, the formalism of quantum mechanics, if applied unrestrictedly, is at best a fragment of such a theory, in need of substantive additional assumptions and equations. So sharp a division about what appears to be a reasonably well-defined question is all the more striking given how much agreement there is otherwise. For all parties to the debate in this book are agreed on realism, and on the need, or the aspiration, for a theory that unites micro- and macroworlds. They all see it as legitimate { obligatory even { to ask whether the fundamental equations of quantum mechanics, principally the Schr¨odingerequation, already constitute such a system.
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