On the Classical Boltzmann Equation for Gases

摘要

With great simplicity we formulate the Boltzmann equation for dilute classical gases from the reduced Liouville equation by using the three assumptions: no threehyphen;body effects, collision time much less than the experimental time, and negligible change in local properties of the system over distances of order of the range of the intermolecular forces. The nature of these assumptions sheds some light on recent attempts to generalize the Boltzmann equation. We find that it is easy formally to relax the first assumption to permit more than twohyphen;body effects. The resulting equation is an intuitive extension of the Boltzmann equation.