Rudolf (Julius Emanuel) Clausius - Life, Work, Tributes

Physicist, born in Koszalin, NW Poland (formerly Köslin, Germany). He studied at Berlin, and in 1869 became professor of natural philosophy at Bonn. He worked on optics and electricity, formulated the second law of thermodynamics, and was influential in establishing thermodynamics as a science.

Rudolf Julius Emanuel Clausius (January 2, 1822 – August 24, 1888), was a German physicist and mathematician.

Clausius was one of the founders of thermodynamics. His most important paper, on the mechanical theory of heat, published in 1850, first stated the basic ideas of the second law of thermodynamics.

Life

Rudolf Clausius started his education at the school of his father. Clausius graduated from the University of Berlin in 1844 where he studied Mathematics and Physics with, among others, Heinrich Magnus, Johann Dirichlet and Jakob Steiner.

In 1870 Clausius organized an ambulance corps in the Franco-Prussian War.

His wife, Adelheid Rimpham, died in childbirth in 1875, leaving him to raise their six children.

Work

Clausius' PhD thesis on the refraction of light proposed that we see a blue sky during the day, and various shades of red at sunrise and sunset (among other phenomena) due to reflection and refraction of light. Later, Lord Rayleigh would show that it was in fact due to the scattering of light, but regardless, Clausius used a far more mathematical approach than his predecessors.

His most famous paper, "Über die bewegende Kraft der Wärme" ("On the Moving Force of Heat and the Laws of Heat which may be Deduced Therefrom") was published in 1850, and dealt with the mechanical theory of heat. Clausius restated the two laws of thermodynamics to overcome this contradiction (the third law was developed by Walther Nernst, during the years 1906–1912).

In 1857, Clausius contributed to the field of kinetic theory after refining August Krönig's very simple gas-kinetic model to include translational, rotational and vibrational molecular motions.

Clausius deduced the Clausius-Clapeyron relation from thermodynamics.

Entropy

In his "Abhandlungen über die mechanische Wärmetheorie, Zweite Abteilung", published in 1867, Clausius first gave a mathematical version of the concept of entropy, and gave it its name.

1 Cl = 1 cal/°C = 4.1868 joules per kelvin (J/K)

Tributes

He was elected a Fellow of the Royal Society of London in 1868 and received its Copley Medal in 1879. The Clausius crater on the Moon was named in his honor. border-style:none;">