Clausius, Rudolf Julius Emanuel (1822-1888)

German physicist, one of the founders of the science of thermodynamics. In 1850 he enunciated its second law: heat cannot pass from a colder to a hotter body.

According to Clausius, there are two types of entropy: the conversion of heat into work, and the transfer of heat from high to low temperature. He concluded that entropy must inevitably increase in the universe.

Clausius was born in Pomerania (now in Poland) and educated at Berlin and Halle universities. He became professor of physics at Zürich 1855, returning to Germany 1867 for similar posts first at Würtzburg and then at Bonn.

Clausius also improved the mathematical treatment of the first law of thermodynamics, and studied the relationship between thermodynamics and kinetic theory. From 1857 onwards, he did important work on the kinetic theory of gases as well as on the theory of electrolysis.