The end of perpetual motion?

In the early 19th century, the dissemination of steam engines promoted the development of thermodynamics. This new branch of physics did not prove the non-existence of perpetual motion, but posited it as an axiom to deduce that an engine’s efficiency could never reach 100%. Some of the energy powering a thermo-mechanical system is inevitably dissipated. Later, as the atomic processes underlying motion and heat were understood, and with the statistical definition of the concept of irreversibility of natural phenomena, the question of perpetual motion was finally answered. While perpetual motion is not impossible in theory, it is extremely improbable. In fact, it is more likely that a monkey typing at random on a keyboard will write War and Peace than that someone will achieve perpetual motion.

William Thompson, On the dynamical theory of heat with numerical results deduced from Mr. Joule’s equivalent of a thermal unit and M. Regnault’s observations on steam
William Thompson
“Transactions of the Royal Society of Edinburgh”, 20, 1853, pt. 2, pp. 261-288
Florence, Museo Galileo Library, Fisica C 029/19
Nicolas Léonard Sadi Carnot, Réflexions sur la puissance motrice du feu et sur les machines propres a développer cette puissance
Nicolas Léonard Sadi Carnot
Paris, Bachelier Libraire, 1824
Florence, Museo Galileo Library, Fisica 0446
Max Planck, Vorlesungen über Thermodynamik
Max Planck
Leipzig, Veit, 1897
Florence, Museo Galileo Library, Fisica 0448
Richard P. Feynman, Robert B. Leighton, Matthew Sands, Feynman Physics
Richard P. Feynman, Robert B. Leighton, Matthew Sands
Amsterdam, Inter European Publications, 1975, vol. 1, pt. 2
Private collection
6 versus 9
Reconstruction by Alberto Fabiani, Artes Mechanicae