next up previous
Next: Quiz Up: Subject of Statistical Thermodynamics Previous: Ensembles

Phase Space

What do we need to characterize a system in an ensemble?

Classical answer: coordinates and momenta of all particles![*]

N particles, each has 3 coordinates and 3 momenta--6N-dimensional space. This is called phase space . Each system is a point in this space. The time evolution is a flow in the phase space!

Ensembles are regions in phase space
Mechanical approach:
Describe each trajectory in phase space
Statistical approach:
Describe the flow in the phase space, averages, distribution, deviations, etc. This is the problem we will discuss in this course.

© 1997 Boris Veytsman and Michael Kotelyanskii
Wed Sep 3 22:38:51 EDT 1997