  After a short introduction to the general Quantum Gravity problem, we compare
a result from the S-matrix description of gravitational interaction due to
Amati, Ciafaloni and Veneziano (ACV) with classical General Relativity results.
In Chapter 1, we introduce the metric produced by a massless particle moving at
the speed of light. In Chapter 2, we review ACV's semiclassical approach to
gravitation and show some of its result. In Chapter 3, we detail the
computation of gravitational field expectation values in a high-energy
scattering process, following ACV's prescriptions. In Chapter 4, we analyze our
results. The main feature is that the leading contributions to the metric
computed in terms of the Feynman diagrams deriving from ACV's model perfectly
reproduce classical results.
