What do strings know about the space they live on?

Hybrid.
Contact: Tobias Barthel (tbarthel@mpim-bonn.mpg.de)

By classical Morse theory, the homology of the free loop space LM on a Riemannian manifold M is build out of closed geodesics in M. String topology, as introduced 20 years about by Chas and Sullivan, can be thought of as a refinement of the homology LM, otherwise a homotopy invariant of M, remembering the extra information of how loops can sometimes be concatenated or cut. I'll give an introduction to string topology, aiming to give an idea of what extra information about M these operations retain, and indicate how it gives us a new perspective on Reidemeister torsion.