We consider second-order differential operators with coefficients which are
Gaussian random fields. When the covariance becomes singular at short dist
ances then the propagators of the Schrodinger equation as well as of the wa
ve equation behave in an anomalous way. In particular, the Feynman propagat
or for the wave equation is less singular than the one with deterministic c
oefficients. We suggest some applications to quantum gravity.