Johannes Rydberg

Johannes Robert Rydberg, known as Janne Rydberg, was a Swedish mathematician and physicist who lived from 1854 to 1919 and whose most important work was on spectroscopy. Born in Halmstad, he studied at the University of Lund, where mathematics was his favourite subject. He took his doctorate there in 1879, with a main dissertation on conic sections and a second thesis on algebraic integrals of algebraic functions, and then served as a docent in mathematics before his interests turned toward mathematical physics. Moving to the physics institute at Lund, he found a relatively simple expression relating the lines in the spectra of the elements, and insisted that the hydrogen constant, now called the Rydberg constant, should appear in every series. He announced the results in 1890, building on Mendeleyev's periodic table. He became a full professor only in 1909, after a protracted and contested appointment process, and was elected a fellow of the Royal Society shortly before his death in Lund.