Seminar by Krzysztof (Chris) Burdzy, University of Washington

How many times can n billiard balls collide in the open d-dimensional space? I will provide some estimates. I will explain how the above question leads to a ``pinned billiard balls'' model. On a large scale, the model seems to have a hydrodynamic limit. The parameters of the conjectured limit should satisfy simple nonlinear PDEs. While the existence and properties of the conjectured hydrodynamic limit are open questions, I will provide a quite complete analysis of the conjectured PDE.