Possibility in quantum mechanics

BRUNO BORGE; OLIMPIA LOMBARDI

Santiago de Chile

Conferencia; Charla invitada: Fourth Chilean Conference on the Philosophy of Physics; 2024

Pontificia Universidad Católica de Chile

The Modal-Hamiltonian Interpretation (MHI) of quantum mechanics belongs to the modal family: it is a realist, non-collapse interpretation, according to which the quantum state describes the possible properties of a system but not its actual properties. In particular, the Hamiltonian of the closed quantum system plays a decisive role in the rule that selects its definite-valued observables. This presentation will address the ontological framework of MHI, which encompasses possibilism, factualism, and a distinction between case-properties and type-properties (akin to the traditional distinction between determinables and determinates), along with a theory of properties as universals combined with the concept of property bundles. This allows for the postulation of bundles of potential determinates for the same determinable. MHI also takes an anti-Humean stance, by accepting modally loaded facts about the world not outsourcing them to alternative real worlds. In this presentation, we will primarily focus on this latter aspect, specifically addressing the problem of the locus of modality. This refers to the question of where in the ontology the objective modal relations are grounded. Within this framework, the notion of propensities to actualization plays a crucial role. We will explore its significance in the context of current discussions surrounding modality in the metaphysics of science.