  The tail problem for the propagation of a scalar field is considered in a
cosmological background, taking a Robertson-Walker spacetime as a specific
example. The explicit radial dependence of the general solution of the
Klein-Gordon equation with nonminimal coupling is derived, and the
inapplicability of the standard calculation of the reflection and transmission
coefficients to the study of scattering of waves by the cosmological curvature
is discussed.
