文档介绍：International Journal of Theoretical Physics, Vol. 24, No. I, 1985
Quantum Theory as a Universal Physical Theory
David Deutsch ~
Received March 22, 1984
The problem of setting up quantum theory as a universal physical theory is
investigated. It is shown that the existing formalism, in either the conventional
or the Everett interpretation, must be supplemented by an additional structure,
the "interpretation basis." This is a preferred ordered orthonormal basis in the
space of states. Quantum measurement theory is developed as a tool for determin-
ing the interpretation basis. The augmented quantum theory is discussed.
1. INTRODUCTION
The conventional view of quantum theory is that its logical structure
restricts in a fundamental way its domain of potential applicability. It is
believed that a quantum theory has no predictive power unless the quantum
system under consideration is in interaction with an external system to
which quantum theory does not apply (variously called a "macroscopic
observable," the "classical level," the "observer," or an "irreversible pro-
cess"). In that case, quantum theory would be meaningless or inconsistent
if regarded as a universal physical theory. (Whether or not a theory is
universal is a purely logical property of the theory. This must be distin-
guished from the empirical question whether quantum theory is universally
true. The latter question is not addressed in this paper.) The purpose of
this paper is to attack this view by showing how quantum theory may be
formulated in pletely intrinsic way; that is, in such a way that every
entity mentioned in the formulation has a realization within the quantum
formalism. In particular the notion of "measurement," which is required
for testing the theory, has such a realization.
A reformulation of quantum theory allowing its interpretation as a
universal theory is highly desirable for practical, philosophical, and heuristic
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