The British scientist William Thomson, Lord Kelvin (1824–1907), was the son of an engineering professor. Kelvin published more than six hundred scientific articles in his career on a wide variety of topics in the physical sciences. As an applied scientist, he invented a number of scientific instruments; one of them, the mirror-galvanometer, was used in the first successful trans-Atlantic underwater telegraph cable, which ran from Ireland to Newfoundland. His success in applied science earned him fame, wealth, and a noble title: Baron Kelvin of Largs.

In theoretical science, Kelvin was a pioneer in tying together ideas about electricity and magnetism, heat and light, and thermal and gravitational energy. He worked with James Joule (1818–1889) in formulating the first law of thermodynamics, and concluded that there exists an “absolute zero” temperature (the lowest possible temperature in the universe). Today, the temperature scale based on absolute zero is called the Kelvin scale in his honor.