Recurrence for quenched random Lorentz tubes.

link: http://arxiv.org/abs/0909.3069
Abstract

We consider the billiard dynamics in a cylinder-like set that is tessellated
by countably many translated copies of the same d-dimensional polytope. A
random configuration of semidispersing scatterers is placed in each copy. The
ensemble of dynamical systems thus defined, one for each global choice of
scatterers, is called `quenched random Lorentz tube'. For d=2 we prove that,
under general conditions, almost every system in the ensemble is recurrent. We
then extend the result to more exotic two-dimensional tubes and to a fairly
large class of d-dimensional tubes, with d > 2.