  We present a one-dimensional scattering theory which enables us to describe a
wealth of effects arising from the coupling of the motional degree of freedom
of scatterers to the electromagnetic field. Multiple scattering to all orders
is taken into account. The theory is applied to describe the scheme of a
Fabry-Perot resonator with one of its mirrors moving. The friction force, as
well as the diffusion, acting on the moving mirror is derived. In the limit of
a small reflection coefficient, the same model provides for the description of
the mechanical effect of light on an atom moving in front of a mirror.
