In this paper we have presented heuristic calculations for the fluctuations of the gravitational energy density and of the gravitational field. Our calculations, based on the uncertainty principle and an essential form of special relativistic causality, have been performed in a Newtonian framework only, even though the functional shape of the potential would not be very different in, say, a standard AdS space. However we have traded exactness and rigour for an intuitive picture of the fluctuations, which allows for much more complex situations than any of those treated in the past. This leads to testable experimental predictions: in particular, we have focused our attention on the propagation of light and we have derived the correlation functions for the irradiance inside a two-arm interferometer.
