Ed Fix
The equipartition law, like all such empirical laws, is a statistical approximation that becomes less and less accurate as the population of gas molecules becomes smaller.
The answer is given by the energy
equipartition law.
Actually the whole point of LTE and energy
equipartition law is to make sure that all degrees of freedom of material particles interact sufficiently so that all energy forms are «well mixed».
The problem here is that the energy
equipartition law is a statistical result, not a precise law such as «Action and reaction are equal and opposite.»
TomVonk says: August 10, 2010 at 1:53 am «I observe that after 300 comments, not a single one contested either the time symmetry or the energy
equipartition law.
Not exact matches
Several commenters (including myself) have pointed out that
equipartition is not an invariable
law and is not valid under conditions of radiative pumping for example.