Toward a Collective Treatment of Quantum Gravitational Interactions

Abstract

In this paper we study the gravitational effects induced by the quantum fluctuations of the energy–momentum tensor of scalar fields. Our treatment is based on the two-point correlation function of this operator. In a large N limit, this treatment constitutes the next contribution after the semiclassical treatment. The specific example we study are the gravitational interactions between outgoing configurations giving rise to Hawking radiation and in-falling configurations. Even when the latter are in vacuum state, the interactions grow boundlessly upon approaching the horizon. Their main effect is to wash out the trans-Planckian correlations which existed in a given background geometry. When evaluated in the lowest order, these interactions express themselves in terms of a stochastic ensemble of metric fluctuations. The propagation of Hawking radiation in this ensemble resembles that of sound propagation in a random medium. The analogies with acoustic black holes are manifest even though certain features differ.