Johannes Rydberg

Born on 8 November 1854 in Halmstad, Sweden, Johannes Rydberg was a mathematician, physicist, and spectroscopy pioneer known for developing the Rydberg formula for predicting the wavelengths of the spectral lines of the chemical elements. He attended the University of Lund, where he studied mathematics, earning his bachelor’s degree in 1875 and his doctorate in 1879. He was later appointed assistant lecturer in mathematics and then in physics. Rydberg first focused on the periodic table before taking up the study of the line spectra of various elements. Despite a wealth of data, no one had yet found a way to systematically arrange the spectra. The formula Rydberg devised not only revealed the relations between the various chemical elements but also provided the basis for the structure of the atom proposed in 1913 by Niels Bohr. Rydberg’s published report of his findings in 1890 became a classic on the subject and is regarded as the beginning of modern spectroscopy. Despite his groundbreaking research and international reputation, Rydberg struggled to gain a professorship at Lund University. He finally was granted an appointment in 1901 but didn’t become a full professor until 1909. He worked as an accountant on the side to make ends meet. By 1914 Rydberg had become very ill, and he was forced to resign his position the following year. He died in 1919 at age 65. (Photo credit: AIP Emilio Segrè Visual Archives, W. F. Meggers Collection)

Date in History: 8 November 1854