Overture in B major

This chapter aims to provide a microscopic meaning of entropy, which we have identified as the new non-mechanical “coordinate” that allows us to describe thermal exchanges. We begin by studying some simple thermodynamics examples. The conclusions we shall draw, albeit still rather vague, will lead us to the cornerstone of statistical mechanics, the Boltzmann hypothesis. In fact, all the little music we shall play is written in a harmonic scale whose pitch, in view of this landmark achievement by Ludwig Boltzmann, is surely B major.