1822-1888

German physicist considered, along with Lord Kelvin, to be one of the originators of the second law of thermodynamics. Clausius reanalyzed the earlier work of Carnot on the efficiency of steam engines, taking into account the conversion of heat energy into mechanical work. In 1865 he suggested that he ratio of heat energy exchanged between systems to absolute temperature be considered a change in a new function, the entropy, of the systems.