We consider a quantum mechanical system of N bosons with relativistic
dispersion interacting through a mean field Coulomb potential (attractive or
repulsive). We choose the initial wave function to describe a condensate, where
the N bosons are all in the same one-particle state. Starting from the N-body
Schroedinger equation, we prove that, in the limit N goes to infinity, the time
evolution of the one-particle density is governed by the relativistic nonlinear
Hartree equation. This equation is used to describe the dynamics of boson stars
(Chandrasekhar theory). The corresponding static problem was rigorously solved
by Lieb and Yau.