... study of 2D string theory 34 2 Matrix models and random surfaces Fig II.1: Duality between Feynman graphs and discretized surfaces Similarly, one can consider 3, 4, etc matrix models Their definition ... fundamental physics But suddenly another reason was found Each string possesses a spectrum of excitations All of them can be interpreted as particles with different spins and masses For a closed string, ... with systems where some random processes are expected Indeed, this is a typical behaviour for the systems described by matrix models Statistical physics Historically, for the first time matrix models...