Basics of Statistical Physics

Statistical physics is the theory that relates macroscopic properties of materials to their microscopic constitution. Obviously a detailed study of systems containing on the order of 1023 particles is out of the question, actually even useless, so we must resort to statistical methods. There are many ways to introduce statistical mechanics, of which we will present two. Besides this, there are several different ‘models’, called ensembles, to arrive at a relation between microscopic and macroscopic properties of materials. Although these ensembles in principle are different, for sufficiently large systems they provide identical results. While developing statistical physics we will automatically construct thermodynamics, a macroscopic theory of invaluable help in describing for example phase transitions. In principle no knowledge of thermodynamics is assumed in order to understand the present notes, although obviously it will be of great help to have some acquaintance with it.