This hypothesis states that trajectories in phase space are uniformly distributed over surfaces of constant energy. First proposed by Boltzmann and Gibbs, it does not hold for all systems but is true for liquids and gases. One of its key consequences is that an average over an ensemble is equal to a time average. FTP, name 
This hypothesis states that trajectories in phase space are uniformly distributed over surfaces of constant energy. First proposed by Boltzmann and Gibbs, it does not hold for all systems but is true for liquids and gases. One of its key consequences is that an average over an ensemble is equal to a time average. FTP, name this hypothesis underlying much of statistical mechanics, which states that, if you wait long enough, the system will assume every possible microstate.
This hypothesis states that trajectories in phase space are uniformly distributed over surfaces of constant energy.
{ergodic} hypothesis