Wilhelm Eduard Weber

Wilhelm Eduard Weber (1804-1891) was a German physicist who worked in Prussia and Hanover. He belonged to the generation that turned the study of electricity and magnetism into a quantitative science. Together with Carl Friedrich Gauss he built, in 1833, one of the first electromagnetic telegraphs, and the SI unit of magnetic flux, the weber, is named after him.

Born in 1804 in Wittenberg, he was the son of Michael Weber, a professor of theology. When the university there was dissolved, the family moved to Halle. Wilhelm, the middle of three brothers, was first taught by his father and then attended the orphanage and grammar school before entering university to study natural philosophy. Before turning twenty he co-wrote with his brother Ernst Heinrich, an anatomist, a book on wave theory and fluidity that earned both of them a considerable reputation. Acoustics remained his favourite subject, and his work on reed organ pipes at Halle drew the attention of Alexander von Humboldt and Gauss.

In 1831, on Gauss's recommendation, he was appointed professor of physics at Göttingen at the age of twenty-seven. His lectures were lively and thought-provoking, but he believed physics could not be learned from lectures alone. He urged students to experiment and gave them free use of the laboratory, which was unusual at the time. With Gauss he set up a telegraph linking the university laboratory with the observatory, about three kilometres away. In 1837 he was one of the Göttingen Seven, professors who refused to swear loyalty to the new king of Hanover after a constitutional change. Dismissed for his liberal views, he travelled, including to England, taught at Leipzig from 1843 to 1849, and then returned to Göttingen, where he eventually directed the observatory.

His best-known contribution is the unification of electrical units. He systematically repeated the quantitative experiments of Ørsted and Faraday, linked them to Gauss's magnetic measurements, and designed highly precise instruments such as the electrodynamometer. His aim was to do for electricity what Newton had done for mechanics: to connect its quantities in a single coherent system. In 1856, with Rudolf Kohlrausch, he found that the ratio of electrostatic to electromagnetic units matched the speed of light. This result encouraged Maxwell to propose that light is an electromagnetic wave, and Weber used it to develop his own electrodynamic theory. He was also the first to use the letter c for the speed of light, in a paper of that year. His geomagnetic work, including the Atlas des Erdmagnetismus made with Gauss, helped prompt the founding of magnetic observatories across the major powers.

Weber died in Göttingen in 1891, aged eighty-six. He had been a foreign member of the Royal Swedish Academy of Sciences since 1855. His influence reaches modern physics, metrology and the history of electromagnetism, which he helped turn into a measurable theory.