## Quick Reference

The theory, proposed by Ludwig Boltzmann and given some theoretical support by James Clerk Maxwell, that the energy of gas molecules in a large sample under thermal equilibrium is equally divided among their available degrees of freedom, the average energy for each degree of freedom being *kT*/2, where *k* is the Boltzmann constant and *T* is the thermodynamic temperature. The proposition is not generally true if quantum considerations are important, but is frequently a good approximation.

*Subjects:*
Chemistry — Physics.