  Hamilton's equations with noise and friction possess a hidden supersymmetry,
valid for time-independent as well as periodically time-dependent systems. It
is used to derive topological properties of critical points and periodic
trajectories in an elementary way. From a more practical point of view, the
formalism provides new tools to study the reaction paths in systems with
separated time scales. A 'reduced current' which contains the relevant part of
the phase space probability current is introduced, together with strategies for
its computation.
