Editing Phase space (section)

=== Statistical ensembles in phase space ===
The motion of an [[Statistical ensemble (mathematical physics)|ensemble]] of systems in this space is studied by classical [[statistical mechanics]]. The local density of points in such systems obeys [[Liouville's theorem (Hamiltonian)|Liouville's theorem]], and so can be taken as constant. Within the context of a model system in classical mechanics, the phase-space coordinates of the system at any given time are composed of all of the system's dynamic variables. Because of this, it is possible to calculate the state of the system at any given time in the future or the past, through integration of Hamilton's or Lagrange's equations of motion.