Topological insulators: experimental results and theoretical models

In this talk I will discuss some basic physical aspects of topological insulators, emphasizing how they have been observed experimentally and how they are modeled theoretically. Then I will describe the relevant space of (equivariant) Hamiltonians describing such gapped systems and gesture towards a role for KR-theory. The basic role of this talk is to give the physics context for and to pose the problem addressed by the article "Twisted Equivariant Matter"  of Freed and Moore, which will be the subject of the next talks.