  We consider a quantum theory of elastic light scattering from a macroscopic
atomic sample existing in the Bose-Einstein condensate (BEC) phase. The
dynamics of the optical excitation induced by an incident photon is influenced
by the presence of incoherent scattering channels. For a sample of sufficient
length the excitation transports as a polariton wave and the propagation
Green's function obeys the scattering equation which we derive. The polariton
dynamics could be tracked in the outgoing channel of the scattered photon as we
show via numerical solution of the scattering equation for one-dimensional
geometry. The results are analyzed and compared with predictions of the
conventional macroscopic Maxwell theory for light scattering from a
non-degenerate atomic sample of the same density and size.
