We investigate geodesics in non-homogeneous vacuum pp-wave solutions and
demonstrate their chaotic behavior by rigorous analytic and numerical methods.
For the particular class of solutions considered, distinct "outcomes" (channels
to infinity) are identified, and it is shown that the boundary between
different outcomes has a fractal structure. This seems to be the first example
of chaos in exact radiative spacetimes.Comment: 15 pages (latex),12 figures (gif), to appear in Class. Quantum Gra