  Experiments on dewetting thin polymer films confirm the theoretical
prediction that thermal noise can strongly influence characteristic time-scales
of fluid flow and cause coarsening of typical length scales. Comparing the
experiments with deterministic simulations, we show that the Navier-Stokes
equation has to be extended by a conserved bulk noise term to accomplish the
observed spectrum of capillary waves. Due to thermal fluctuations the spectrum
changes from an exponential to a power law decay for large wavevectors. Also
the time evolution of the typical wavevector of unstable perturbations exhibits
noise induced coarsening that is absent in deterministic hydrodynamic flow.
