  In this paper we present an overview of results in the literature regarding
the thermodynamical scaling of the dynamics of liquids and polymers as measured
from high-pressure measurements. Specifically, we look at the scaling exponent
gamma, and argue that it exhibits the limiting behavior gamma=4 in regimes for
which molecular interactions are dominated by the repulsive part of the
intermolecular potential. For repulsive potentials of the form U(r)= r^n, gamma
has been found to be related to the exponent n via the relation gamma = n/3.
Therefore, this limiting behavior for gamma would suggest that a large number
of molecular systems may be described by a common repulsive potential U(r)~ r^n
with n~12.
