Bohmian Mechanics and Quantum Equilibrium

We report here on our work on Bohmian mechanics. A much more detailed presentation will be published elsewhere [7]. According to the quantum formalism, measurements performed on a quantum system with definite wave function typically yield random results. However, the quantum dynamics governing the evolution of the wave function over time, at least when no measurement is being performed, and given, say, by Schrödinger’s equation, is completely deterministic. Thus if all physical processes, including those we call measurements, are governed by the same fundamental laws, and if one assumes the wave function to be the complete description of the physical state, one arrives at an inconsistency, often referred to as “the measurement problem” or the problem of the “collapse of the wave function.” Debates over this were strongly influenced by “quantum epistemology”—by the obligatory reference to the observer in a measurement, whose act of “observation” somehow creates the random outcome. In recent years, however, the growing disenchantment with this irreducible reference to the observer has begun to assume the form of serious doubts about the validity and meaning of the quantum formalism.