Geometry and Dynamics Seminar: A Tale of Four Billiards – Focusing on the Nonconventional Ones
Guest Lecturer: Professor Sergei Tabachnikov, Department of Mathematics, Pennsylvania State University, USA
What happens when classical billiards meet symplectic geometry and modern dynamics?
The Institute of Advanced Studies is honored to welcome Professor Sergei Tabachnikov, Professor of Mathematics at Pennsylvania State University, as part of the IAS Distinguished Scholars series.
In his talk, “A Tale of Four Billiards: Focusing on the Nonconventional Ones,” Professor Sergei Tabachnikov will explore how variations on classical billiard systems open new windows into modern geometry and dynamics.
Starting from the traditional Birkhoff billiard, whose periodic orbits form polygons of extremal perimeter, he will show how replacing “perimeter” with “area” and “inscribed” with “circumscribed” gives rise to three other intriguing billiard-like systems. Two of these extend naturally to symplectic spaces, leading to symplectic inner and outer billiards—systems with rich geometric and dynamical behavior.
Professor Tabachnikov will discuss periodic orbits and large-scale trajectories in these models, and reveal how they connect to Minkowski billiards, a central topic in contemporary symplectic topology.
Wednesday, 14 January 2026, 14:00
Where: Room 309, Schreiber Building
The lecture will be conducted in English and is open to the public.
Light refreshments will be served before the lecture.
