Upcoming talks
7 November 2026
Sebastian de Haro (Amsterdam), “Dualities and the Geometric View of Theories“
In the recent literature on the semantic conception, it has been argued that a bare collection of models subject to kinematical or dynamical conditions is not sufficient to define a theory: additional structure on the space of models is required. In this talk, I will develop a geometric view of theories, according to which a physical theory is a structured space of models equipped with topological and geometric structure, typically organised by a moduli space. Building on this, I propose a more specific structure that covers many examples of interest, the model bundle, in which putative ‘theories’ are models (fibres) over a base. The fibres contain states and quantities, the base is usually a moduli space, and a structure group of quasi-dualities acts on the fibres; the total space thereby carries natural geometric structure. I will illustrate this with the Fourier transformation and S-duality in the Seiberg-Witten theory. In the latter case, the moduli space is the complex plane with punctures and the modular group acts as the structure group. Quasi‑dualities define local transition functions between local trivialisations; when the bundle is trivial, dualities are recovered as transitions between global trivialisations. I will discuss the interpretation of this structure, and how it relates to philosophical discussions of sophistication and reduction.
3 December 2026
Francisco Calderón, TBA