Phase space

A space in which all possible states of a system are represented, with each possible state of the system corresponding to one unique point in the phase space. Phase space can be multidimensional, from a one-dimensional “phase line” to a two-dimensional “phase plane.” For mechanical systems, phase space can trace the dynamic path of position and momentum of a particle; for thermodynamic systems, phase diagrams can trace the evolution of macroscopic measures of pressure-volume or entropy-temperature.