  We compare the capillary levelling of a random surface perturbation on a thin
polystyrene film with a theoretical study on the two-dimensional
capillary-driven thin film equation. Using atomic force microscopy, we follow
the time evolution of samples prepared with different initial perturbations of
the free surface. In particular, we show that the surface profiles present long
term self-similarity, and furthermore, that they converge to a universal
self-similar attractor that only depends on the volume of the perturbation,
consistent with the theory. Finally, we look at the convergence time for the
different samples and find very good agreement with the analytical predictions.
