Boundaries between spacetime regions, boundaries between interacting physical systems, and relations across boundaries, play an important role in contemporary physics. Boundary degrees of freedom, in particular, have recently raised much interest in the literature on general relativity, gauge field theories and black holes.  The appearance of these degrees of freedom, required to preserve gauge invariance, raises important conceptual questions. What is the metaphysical status of the corresponding observables? Should they be considered an artificial redundancy, or genuine real physical variables? What do they tell us about the nature of gauge invariance?

A boundary determines a partition of a system. In quantum physics, the partition between the system and the observing apparatus can be taken as a basic element of the theory. This is particularly evident in information-based interpretations of quantum mechanics, such as relational quantum mechanics or the more recent q-bism, but can also be found for instance in Everett’s relative states. In all these cases, physical observables are always associated with boundaries.

This conference will bring together experts from different directions of investigation, to reflect on the common relational aspect underlying observables defined by boundaries and partitions. The discussion will focus on the philosophical and foundational consequences of different positions on the nature of these observables, and, more generally, on the nature of gauge itself. We would like to discuss how to think about a metaphysics based on relations in light of this recent progress within physics and different philosophical frameworks, in particular structural realism.

The conference will be followed by the 20th annual graduate student conference on the Philosophy of Logic, Mathematics, and Physics. This event provides a unique opportunity for Canadian and international graduate students to present their work. The participants of the conference are encouraged to stay for this event and contribute to the discussions, providing feedback and mentoring for the participating students.

Photo by Mark Basarab on Unsplash