Photo credit: Nobel Foundation — File:Onsager 1968.jpg (Wikimedia Commons) · Public domain
Lars Onsager
1903–1976 · Norway, United States · 20th century
Nobel Chemistry 1968
Norwegian-American theoretical chemist famous for the reciprocal relations of irreversible thermodynamics and the exact solution of the two-dimensional Ising model.
Nobel Prize work
Onsager discovered the reciprocal relations — that when two irreversible flows such as heat and matter transport are coupled, the cross-coefficients are equal. Published in 1931 and grounded in microscopic reversibility, they became the cornerstone of the thermodynamics of irreversible processes.
Fields
Related topics
Enthalpy, entropy, Gibbs free energy
Combines enthalpy and entropy through Gibbs energy to predict the thermodynamically allowed direction at fixed temperature and pressure.
Linking the microscopic and macroscopic
The bridge between atoms and thermometers: S = k_B ln W, the Gibbs entropy formula, ensembles and fluctuations — how every thermodynamic quantity is an average (or a fluctuation) of molecular statistics.