We begin, as a way of entering our subject, by characterizing a particular interpretation of quantum theory which, although not representative of the more careful formulations of some writers, is the most common form encountered in textbooks and university lectures on the subject.

A physical system is described completely by a state functionψ, which is an element of a Hilbert space, and which furthermore gives information only concerning the probabilities of the results of various observations which can be made on the system. The state functionψis thought of as objectively characterizing the physical system, i.e., at all...

The task of quantizing general relativity raises serious questions about the meaning of the present formulation and interpretation of quantum mechanics when applied to so fundamental a structure as the space-time geometry itself. This paper seeks to clarify the foundations of quantum mechanics. It presents a reformulation of quantum theory in a form believed suitable for application to general relativity.

The aim is not to deny or contradict the conventional formulation of quantum theory, which has demonstrated its usefulness in an overwhelming variety of problems, but rather to supply a new, more general and complete formulation, from which the conventional...

The preceding paper puts the principles of quantum mechanics in a new form.¹ Observations are treated as a special case of normal interactions that occur within a system, not as a new and different kind of process that takes place from without. The conventional mathematical formulation with its well-known postulates about probabilities of observations is derived as aconsequenceof the new or “meta” quantum mechanics. Both formulations apply as well to complex systems as to simple ones, and as well to particles as to fields. Both supply mathematical models for the physical world. In the new or “relative state”...

Despite its enormous practical success, quantum theory is so contrary to intuition that, even after 45 years, the experts themselves still do not all agree what to make of it. The area of disagreement centers primarily around the problem of describing observations. Formally, the result of a measurement is a superposition of vectors, each representing the quantity being observed as having one of its possible values. The question that has to be answered is how this superposition can be reconciled with the fact that in practice we only observe one value. How is the measuring instrument prodded into making up...

Although forty five years have passed since Heisenberg first unlocked the door to the riches of modern quantum theory, agreement has never been reached on the conceptual foundations of this theory. The disagreement is well illustrated by the variety of opinions expressed in the other lectures we have heard in the past few days, and I shall make no attempt to summarize it. Let me turn immediately to my main purpose, which is to describe one of the most bizarre and at the same time one of the most straightforward interpretations of quantum mechanics that has ever been put forward,...

Although the structure of the quantum theory in the opinion of almost all physicists is free from contradiction, questions about the consistency of its interpretation have been and continue to be posed. The view expressed in most texts and taught in many classes derives from the work of von Neumann¹ in the early thirties; it implies what is close to a Cartesian dualism dividing mind and body which, though consistent (and perhaps even respectable in the 17th century^2,3), seems somewhat of an anachronism at present.^4,5

Von Neumann proposed that the interpretation of measurement—or the means by which we come...

In this paper we wish to explore the probability interpretation within the framework of the Everett interpretation of quantum mechanics [1, 2]. After a brief review of the Everett interpretation, including a critique of Everett’s version of the probability interpretation, we propose a “two step” solution to the problem. In the first step an apparatus measures the relative frequency with which a given event occurs in a collection of independent, identically prepared systems. (Relative frequency is treated as an observable and is represented by a Hermitean operator. This approach to relative frequency was discussed by this author in his Ph.D....