Rydberg born 1854 in Sweden as only child. Father died when Rydberg was 4 forcing poverty. Excelled in math and physics at school. Earned bachelor's 1875 and PhD 1879 from Lund. Became docent in math 1880 then physics 1882. Investigated atomic weights in periodic table without success. Built on Balmer's hydrogen formula to create Rydberg formula 1888 for all elements. Published generalization 1890. Denied full professorship until 1909 despite expert support. Worked side jobs as bank examiner and actuary for income. Illness slowed research from 1913 and caused death 1919 at 65. Succeeded by student Manne Siegbahn. Rydberg formula named constant and unit after him. Rydberg atoms named for high quantum states. His spectra work anticipated Bohr's atomic model.