Lars Onsager was born in Oslo (then known as Christiania), Norway, in 1903. His parents were Erling Onsager and Ingrid Kirkeby Onsager.

Onsager excelled in chemistry from an early age, and his prodigious talent in the field was exhibited while still a student. One of the topics that caught his attention concerned the chemistry of solutions. In 1884, Svante Arrhenius had proposed a theory of ionic dissociation that explained a number of observations about the conductivity of solutions and, eventually, a number of other solution phenomena. Over the next half century, chemists worked on refining and extending the Arrhenius theory.

The Dutch chemist Peter Debye and the German chemist Erich Hückel, had proposed a revision of the Arrhenius theory that explained some problems not yet resolved--primarily, whether ionic compounds are or are not completely dissociated ("ionized") in solution. After much experimentation, Arrhenius had observed that dissociation was not...