1,721,037 research outputs found
Identity, Superselection Theory and the Statistical Properties of Quantum Fields
Full text linkThe permutation symmetry of quantum mechanics is widely thought to imply a sort of metaphysical underdetermination about the identity of particles. Despite claims to the contrary, this implication does not hold in the more fundamental quantum field theory, where an ontology of particles is not generally available. Although permutations are often defined as acting on particles, a more general account of permutation symmetry can be formulated using superselection theory. As a result, permutation symmetry applies even in field theories with no particle interpretation. The quantum mechanical account of permutations acting on particles is recovered as a special case
Primitive Ontology and the Structure of Fundamental Physical Theories
Full text linkFor a long time, it was believed that it was impossible to be realist about quantum mechanics. It took quite a while for the researchers in the foundations of physics, beginning with John Stuart Bell (1987), to convince others that such an alleged impossibility had no foundation. These days there are several quantum theories that can be interpreted in a realist fashion, among which Bohmian mechanics, the Ghirardi-Rimini-Weber (GRW) theory, and the many-worlds theory.
The debate, though, is far from being over. In what respect should we be realist regarding these theories? At least two different proposals have been made: on one hand, some insist on a direct ontological interpretation of the wave function as representing physical bodies, on the other hand are those who claim that quantum mechanics is not really about the wave function.
In this chapter I will present and discuss one proposal of the latter kind that focuses on the notion of primitive ontology
The ‘Unromantic Pictures’ of QuantumTheory
No full textI am concerned with two views of quantum mechanics that John S. Bell called “unromantic”: spontaneous wave function collapse and Bohmian mechanics. I discuss some of their merits and report about recent progress concerning extensions to quantum field theory and relativity. In the last section, I speculate about an extension of Bohmian mechanics to quantum gravity. PACS numbers: 03.65.Ta; 03.70.+k. Key words: quantum theory without ob-servers; Ghirardi–Rimini–Weber model of spontaneous wave function collapse
On Bohmian Mechanics, Particle Creation, and Relativistic Space-Time: Happy 100th Birthday, David Bohm!
No full textThe biggest and most lasting among David Bohm’s (1917–1992) many achievements is to have proposed a picture of reality that explains the empirical rules of quantum mechanics. This picture, known as pilot wave theory or Bohmian mechanics among other names, is still the simplest and most convincing explanation available. According to this theory, electrons are point particles in the literal sense and move along trajectories governed by Bohm’s equation of motion. In this paper, I describe some more recent developments and extensions of Bohmian mechanics, concerning in particular relativistic space-time and particle creation and annihilation
On Spontaneous Wave Function Collapse and Quantum Field Theory
No full textOne way of obtaining a version of quantum mechanics without observers, and thus of solving the paradoxes of quantum mechanics, is to modify the Schrödinger evolution by implementing spontaneous collapses of the wave function. An explicit model of this kind was proposed in 1986 by Ghirardi, Rimini, and Weber (GRW), involving a nonlinear, stochastic evolution of the wave function. We point out how, by focussing on the essential mathematical structure of the GRW model and a clear ontology, it can be generalized to (regularized) quantum field theories in a simple and natural way. PACS numbers: 03.65.Ta; 03.70.+k. Key words: quantum field theory without observers; Ghirardi–Rimini–Weber model; identical particles; second quantization.
- …
