The debate over the validity of the principle of material frame indifference of modern continuum mechanics, as recently discussed by Ryskin [Phys. Rev. A 32, 1239 (1985)], is examined from a more rigorous theoretical standpoint based on statistical mechanics. It is shown that constitutive equations can only represent special solutions of the microscopic dynamics and, as such, can have a larger invariance group than the Galilean group. While there are reasons to question the general validity of material frame indifference, these doubts arise exclusively from the presence of unbalanced molecular Coriolis forces whose effect becomes vanishingly small in the classical continuum limit. Hence it is argued that statistical mechanics is in excellent approximate agreement with material frame indifference for the description of physical phenomena which lie strongly within the classical continuum limit.

• Received 15 December 1986

DOI:https://doi.org/10.1103/PhysRevA.36.4522