On the fundamentally probabilistic nature of the knowledge of a microsystem in the framework of the Elementary Process Theory

Abstract

A fundamental question in the debate about the interpretations of quantum mechanics (QM) is whether the universe is fundamentally deterministic or fundamentally probabilistic. This self-contained paper shows for a microsystem made up of a single neutron that is initially at rest in a stationary force-free environment, that even if the individual processes by which the microsystem evolves are fundamentally deterministic as described by a strictly deterministic model of the Elementary Process Theory (EPT), then still our most precise knowledge of the outcome of a position measurement on the microsystem is fundamentally probabilistic. Generalizing, the conclusion is that the EPT is inconsistent with orthodox QM, but consistent with $\psi$-epistemic QM.