Description
A gas dynamics can be modelled by a billiard made of hard spheres, moving according to the laws of classical mechanics. Initially the spheres are randomly distributed according to a probability measure which is then transported by the flow of the deterministic dynamics. Since the seminal work of Lanford, it is known that the gas density converges in the kinetic limit towards the Boltzmann equation (at least for a short time). In this talk, we are going to review several results on the fluctuations of the particle system density around the Boltzmann equation. This is based on joint works with I. Gallagher, L. Saint-Raymond and S. Simonella.
