A facet is not an island: Step-step interactions and the fluctuations of the boundary of a crystal facet

In a recent paper [P.L. Ferrari, M. Prähofer, H. Spohn, Phys. Rev. E 69 (2004) 035102(R)], the scaling law of the fluctuations of the step limiting a crystal facet, as a function of the facet size, was computed. Ferrari et al. use rigorous, but physically rather obscure arguments. Approaching the problem from a different perspective, we rederive more transparently the scaling behavior of facet edge fluctuations as a function of time.