Rudolf Clausius

Born on 2 January 1822 in Köslin, Prussia (now Poland), Rudolf Clausius was a pioneer in thermodynamics. He earned his doctorate from the University of Halle in 1847 and three years later became physics professor at the Artillery and Engineering School at Berlin. That same year he formulated what’s now known as the second law of thermodynamics, noting that heat tends “to equalize temperature differences and therefore to pass from hotter to colder bodies.” He applied his insight to analyzing the efficiency of steam engines. In 1865 Clausius restated his law in terms of a new concept he called entropy, the amount of thermal energy in a system per unit temperature. He found that the entropy of a closed system will always increase. Today thermodynamics is used to analyze engines large and small as well as to investigate big-picture concepts like the ultimate fate of the universe.

Date in History: 2 January 1822