Thermodynamic formalism for dispersing billiards, or how to change temperature of a billiard without changing its speed or laws of motion.

"Thermodynamic formalism" is a basic concept in Ergodic Theory, classic for "nice" dynamical systems like Markov chains or subshifts of finite type. Interestingly, for dispersing billiards, a prototypical model in mathematical physics, it has only been done very recently and only partially (by Viviane Baladi, Jérôme Carrand and Mark Demers), and comes with a few very peculiar quirks. I'll give a hopefully gentle introduction to how and why do this, and talk about my joint work with Mark Demers on statistical properties in an extreme case of the measure of maximal entropy.