Title: Picard groups in chromatic homotopy theory

Abstract: Computation of the stable homotopy groups of spheres is a
long-standing open problem in algebraic topology. I will describe how
chromatic homotopy theory uses localization of categories, analogous to
localization of rings and modules, to split this problem into easier pieces,
called chromatic levels. Each chromatic level is a symmetric monoidal
category, and we can study their Picard groups. I will talk about classical results about these groups,
and about current work on understanding the Picard group at the
second chromatic level.