Khovanov homology is a refinement of the Jones polynomial of a knot. Recently, there have been a number of exciting applications of Khovanov homology to 4-dimensional topology. In this talk, we will use an indirect approach to re-prove one of these results, that Khovanov homology distinguishes some pairs of disks in the 4-ball. Our proof uses a relationship between the Khovanov homology of a strongly invertible knot and its quotient, coming from a stable homotopy refinement of Khovanov homology.

This is joint work with Sucharit Sarkar. Most of the talk should be fairly broadly accessible; in particular, it will not assume knowledge of Khovanov homology.