Dispersing billiards with moving scatterers
  We propose a model of Sinai billiards with moving scatterers, in which the locations and shapes of the scatterers may change by small amounts between collisions. Our main result is the exponential loss of memory of initial data at uniform rates, and our proof consists of a coupling argument for non-stationary compositions of maps similar to classical billiard maps. This can be seen as a prototypical result on the statistical properties of time-dependent dynamical systems. 
Mikko Stenlund, Lai-Sang Young, Hongkun Zhang
math.DS math-ph math.MP