  A version of scattering theory that was developed many years ago to treat
nuclear scattering processes, has provided a powerful tool to study
universality in scattering processes involving open quantum systems with
underlying classically chaotic dynamics. Recently, it has been used to make
random matrix theory predictions concerning the statistical properties of
scattering resonances in mesoscopic electron waveguides and electromagnetic
waveguides. We provide a simple derivation of this scattering theory and we
compare its predictions to those obtained from an exactly solvable scattering
model; and we use it to study the scattering of a particle wave from a random
potential. This method may prove useful in distinguishing the effects of chaos
from the effects of disorder in real scattering processes.
