ABSTRACT
Scattering theory compares the behaviour in the distant past and the distant future of a system evolving in time. The comparison is made relative to some free or unperturbed problem. The given problem, regarded as the perturbed problem, is then measured against the free problem. Specifically, we investigate whether or not solutions of the perturbed problem behave like solutions of the unperturbed problem in either the distant past or distant future or indeed both; that is we enquire into the asymptotic equality of the solutions.
