Thermodynamics and statistical mechanics Thermodynamics describes processes in terms of the overall stability of the initial state versus the final state of a system. First developed to make steam engines more efficient, thermodynamics became an important part of chemistry and physics, thanks to the work of James Clerk Maxwell (1831–1879), Ludwig Boltzmann (1844–1906), and J(osiah) Willard Gibbs (1839–1903). All three used statistical mechanics to describe the average behavior of the molecules in a system. This is necessary given the trillions of molecules present in macroscopic samples a given material.