Plenary Session # 1 Saturday 9 : 00 - 10 :

Large scale phenomena in homotopy theory (Jordan Hall 124) Paul Goerss (Northwestern University) In the late 1940s it wasn’t clear which was the harder problem: the cohomology of Eilenberg-MacLane spaces or the stable homotopy groups of spheres. After the Cartan-Serre work on Eilenberg-MacLane spaces in the early ’50s, people then optimistically set about computing the homotopy groups of spheres, recognizing that this was now a central question in algebraic topology. They discovered a mess. Sixty years on, we know there are many beautiful patterns, but to see them we have to operate on a very large scale, far larger than they could see at the outset. The aim of this talk is to explore these patterns, where they come from, how we can find them, and their connections to other parts of mathematics. We’ll explore the history of the problem as well, so we can see the patterns emerge from the noise of low dimensional calculations.