Introducing the Modal-Hamiltonian Interpretation of quantum mechanics

OLIMPIA LOMBARDI

Lisboa

Seminario; Charla invitada: Lisbon Philosophy of Physics Seminars; 2023

Universidad de Lisboa

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 thepossible properties of a system but not its actual properties. In particular,the Hamiltonian of the closed quantum system plays a decisive role in the rulethat selects the definite-valued observables of the system. In thispresentation I will focus on three points:a) The MHI is effective in solvingthe measurement problem, both in its ideal and its non-ideal versions. Itaccounts for well-known physical situations by conceiving measurement as aprocess that breaks the symmetry ofthe Hamiltonian and, thus, turns an otherwise non definite-valuedobservable into a definite-valued and empirically accessible observable.b) The MHI can be reformulated underan explicitly Galilean-invariant form in terms of the Casimir operators of theGalilean group, leading to results that agree with usual assumptions in thepractice of physics. Then, any realist interpretation that intends to preservethe Galilean invariance of the set of definite-valued observables cannot departtoo far from the MHI.c) According to the MHI, quantum systemsare not individuals, but bundles of the type-properties represented by the observablesof the system. In this ontology of properties, indistinguishability is nolonger a relationship between individual particles, but an internal symmetry ofa system as a whole, and the symmetry of states is not the result of an ad hocsymmetrization, but is due to ontological reasons, that is, to the very structureof the ontology itself.