The Swedish chemist Svante Arrhenius (1859–1927) is most often remembered as one of the founders of modern physical chemistry. Much of his reputation stems from his equation relating the conductivity of a solution to its temperature. His career, however, was far more expansive than either equation or title suggests, and his reputation suffered more than its share of ups and downs.

As a doctoral student at the University of Uppsala, Arrhenius observed that more dilute solutions tend to be more conductive. In his dissertation he hypothesized that salts and other compounds disassociate in aqueous solution, forming electrolytes; a more dilute solution allows for more disassociation and thus is more conductive. His dissertation was met with excitement among younger scientists on the continent, especially Wilhelm Ostwald, who encouraged Arrhenius to leave Sweden. He spent the next five years traveling and developing the theory of electrolytic disassociation. By the mid-1890s this ionic theory was generally accepted by chemists. However, his attempts to link his theories of electric charge to the moon were less successful.

Arrhenius returned to Sweden in 1891 and took a position as a lecturer of physics at the Stockholm Högskola. There he joined the Stockholm Physics Society and became enmeshed in cosmic physics, an interdisciplinary study of cosmological, atmospheric, oceanic, and geological phenomena. Arrhenius’s devotion to this nascent field—particularly his development of the concept of panspermia, the idea that life arrived on earth from spaceborn spores—caused a rift between him and his non-Scandinavian colleagues. In 1903 he was nevertheless awarded the Nobel Prize in Chemistry. As one of the earliest recipients of science’s greatest honor and a Swede, he became deeply involved in future decisions about the prize. This year marks two anniversaries that would have been of interest to this idiosyncratic scientist: the 150th anniversary of his birth, and the 40th anniversary of the first lunar landing.