2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/120880The concept of definability of physical fields within a set-theoretical foundation is introduced. We propose an axiomatic set theory and show the Schroedinger equation and, more generally, a nonlinear sigma model come naturally out of the mathematics of this theory when a physical null postulate is added. Space-time is relational in this theory and quantization of the field proves to be equivalent to definability. Some additional examples of applicability to physics are given.This paper is based on a talk given in the Theory Seminar of the Physics Department (LNS)with suitable revisionsMathematical PhysicsLogictext