abstract: In the early 30's, E. Schrödinger addressed a statistical physics problem featuring amazing analogies with the newly born wave mechanics. It is connected with the large deviation of the empirical measures of random dynamical particle systems, as the number of particles tends to infinity. This thermodynamical limit raises the problem of minimizing some relative entropy under constraints. We show that if in addition we let the temperature tend down to zero, this entropy minimization problem tends to the Monge-Kantorovich optimal transport problem.