Thermodynamics, etymologically the force of fire, is a branch of physics that deals with the dependence of the physical properties of bodies, in the different states of matter, on temperature. It deals with phenomena involving heat exchanges and the transformation of energy into different forms.

With it comes the "arrow of time", unknown to classical mechanics.

Thermodynamics can be approached phenomenologically and/or statistically.

Phenomenological thermodynamics has been the subject of much researches since the 17th century. It relies on experimental observations to establish principles and laws. The vision is macroscopic because, at that time, the concept of atoms had not been established yet.

Statistical thermodynamics, developed from the mid-19th century onwards, is based on molecular considerations and the calculation of probabilities applied to a large number of particles. It aims to analyse the structure of matter and establishes a link between its properties and the principles of phenomenological thermodynamics.

I teach the bachelor second and third year courses, which provide an introduction to thermodynamics for students of mechanics. We do not cover chemical thermodynamics (or only a little).  Given that two of the founding fathers of statistical thermodynamics, Ludwig Boltzmann and Paul Ehrenfest, committed suicide, our forays into this branch of physics will be cautious, with the primary aim of providing a modern understanding of the phenomenological approach, which is the guiding principle of these lectures.