Thermodynamics is the physical science that accounts for the transformations of thermal energy into mechanical energy and its equivalent forms (electricity, self-organization of complex systems), and vice versa. The development of thermodynamics and the introduction of the concept of entropy, a measure of energy and resource degradation, are rooted into the technological ground of the Industrial Revolution (England, XVIII - XIX centuries).  James Watt's steam engine (1765) paved the way to a massive use of coal to generate heat and then work. The conversion of energy from one form to another was investigated by scientists and technicians in order to deeper understand the nature of heat towards increased efficiency. Thermodynamics was founded between 1850 and 1860 by R.W. Thomson, Lord Kelvin, R. Clausius, and J.C. Maxwell, building on the seminal work of L.S. Carnot's Réflexions sur la Puissance Motrice du Feu (Reflections on the Motive Power of Fire, 1824) and the experiments of J.R. Mayer and J.P. Joule about the quantitative equivalence between mechanical work and heat. These studies yielded a set of Laws of Thermodynamics, describing the main principles underlying energy transformations: First Law, energy is conserved; Second Law, entropy cannot decrease in isolated systems; Third Law; entropy is zero when absolute temperature is zero.

During the 20th Century the laws of thermodynamics were applied to the self-organization of complex, far-from-equilibrium systems (biological, economic, and social). Started as an applied science, Thermodynamics rapidly developed into a more general system of knowledge encompassing almost all branches of life sciences. L. Onsager, I. Prigogine, N. Georgescu-Roegen, A. Lotka, and H.T. Odum, among others, contributed to this research and several statements of Thermodynamics laws were tentatively reformulated or introduced a-new.

Further reading

• Thermodynamics, NASA website