The 2026 Serge Lang Undergraduate Lecture will be given on Thursday September 17th by Professor Colin Defant, Harvard University
MUSA and the Department of Mathematics, University of California, Berkeley, present
Title: Combinatorial Billiards
Abstract:
Billiards is a broad subject concerning trajectories of (idealized) light beams that move through a space, occasionally changing direction when they encounter certain obstructions. Combinatorial billiards focuses on billiard trajectories that are so rigid that they can be modeled using combinatorics, algebra, or probability. I will discuss multiple combinatorial billiard systems, each with a distinct flavor. The talk will mention several open problems and will encourage the audience to ponder new questions.
Bio:
Colin Defant is a Benjamin Peirce Fellow at Harvard. He received his Bachelor's degree at the University of Florida before getting his PhD at Princeton. He spent one year as a postdoc at MIT before his position at Harvard. He works on all flavors of combinatorics, and he especially enjoys problems that involve pretty pictures or things that move. Over the past year, Colin has gotten interested in AI for math, aiming to create tools that will benefit (rather than undermine) the math community. He is excited about using AI to prove hard theorems. He is currently trying to develop techniques and strategies to allow undergraduate and PhD-level research to thrive in the age of AI.
Starting in 2023, Colin has worked with Joe Gallian as a co-director of the Duluth Math REU program. He has overseen at least 125 successful undergraduate research projects, at least 40 of which were based on his own work. He enjoys organizing karaoke sessions, pole vaulting, and eating large quantities of food. He is a three-time winner of the Harvard Undergraduate Math Association's annual pie-eating contest.