  We show how the interplay of non-linear dynamics, self-gravity, and
fluctuations leads to self-affine behavior of matter density correlations quite
generically, i.e., with a power-law exponent whose value does not depend in a
very direct way on the specific details of the dynamics. This we do by means of
the Renormalization Group, a powerful analytic tool for extracting asymptotic
behavior of many-body systems
