No Arabic abstract
Bell suggested that a new perspective on quantum mechanics was needed. We propose a solution of the measurement problem based on a reconsideration of the nature of particles. The solution is presented with an idealized model involving non-locality or non-separability, identified in 1927 by Einstein and implicit in the standard interpretation of single slit (or hole) diffraction. Considering particles as being localizable entities leads to an `induced collapse model, a parameter-free alternative to spontaneous collapse models, that affords a new perspective on, emph{inter alia}, nuclear decay.
This paper presents a minimal formulation of nonrelativistic quantum mechanics, by which is meant a formulation which describes the theory in a succinct, self-contained, clear, unambiguous and of course correct manner. The bulk of the presentation is the so-called lq microscopic theory (MIQM), applicable to any closed system $S$ of arbitrary size $N$, using concepts referring to $S$ alone, without resort to external apparatus or external agents. An example of a similar minimal microscopic theory is the standard formulation of classical mechanics, which serves as the template for a minimal quantum theory. The only substantive assumption required is the replacement of the classical Euclidean phase space by Hilbert space in the quantum case, with the attendant all-important phenomenon of quantum incompatibility. Two fundamental theorems of Hilbert space, the Kochen-Specker-Bell theorem and Gleasons theorem, then lead inevitably to the well-known Born probability rule. For both classical and quantum mechanics, questions of physical implementation and experimental verification of the predictions of the theories are the domain of the macroscopic theory, which is argued to be a special case or application of the more general microscopic theory.
A modified version of relational quantum mechanics is developed based on the three following ideas. An observer can develop an internally consistent description of the universe but it will, of necessity, differ in particulars from the description developed by any other observer. The state vector is epistomological and relative to a given quantum system as in the original relational quantum mechanics. If two quantum systems are entangled, they will observe themselves to be in just one of the many states in the Schmidt biorthonormal decomposition and not in a linear combination of many.
We show that quantum mechanics is the first theory in human history that violates the basic a priori principles that have shaped human thought since immemorial times. Therefore although it is more contrary to magic than any body of knowledge could be, what could be called its magic precisely resides in this violation.
The rationale for introducing non-hermitian Hamiltonians and other observables is reviewed and open issues identified. We present a new approach based on Moyal products to compute the metric for quasi-hermitian systems. This approach is not only an efficient method of computation, but also suggests a new perspective on quasi-hermitian quantum mechanics which invites further exploration. In particular, we present some first results which link the Berry connection and curvature to non-perturbative properties and the metric.
Understanding the quantum measurement problem is closely associated with understanding wave function collapse. Motivated by Breuers claim that it is impossible for an observer to distinguish all states of a system in which it is contained, wave function collapse is tied to self observation in the Schmidt biorthonormal decomposition of entangled systems. This approach provides quantum mechanics in general and relational quantum mechanics in particular with a clean, well motivated explanation of the measurement process and wave function collapse.