MiS Preprint Repository

The time spent by a ferromagnetic system, ruled by a Kac potential $J_{\gamma }$, in one of the two phases has the order of magnitude of 1 divided by the probability of observing so a strong fluctuation that an interface is produced and move until the opposite phase is reached. That probability is exponentially small in the intensity $\gamma$ of the potential and the free energy gap between one of the phase and the next stationary state, where both phases are present in the same quantity separated by an interface.