J. Michael Kosterlitz

Brown University

John Michael Kosterlitz is a British–American physicist at Brown University who co-discovered one of the most important phase transitions in statistical physics. Together with David Thouless, he described the Kosterlitz–Thouless (KT) transition — a topological phase transition in two-dimensional systems driven by the unbinding of vortex–antivortex pairs. This discovery resolved a long-standing puzzle about why thin films of helium and superconductors can exhibit quasi-long-range order, and it introduced the concept of topological defects as drivers of phase changes. The KT transition is now understood to underlie phenomena in superfluid films, liquid crystals, high-temperature superconductors, and Josephson junction arrays. Kosterlitz shared the 2016 Nobel Prize in Physics for these revelations about topological matter. His contributions are foundational to the theory of two-dimensional quantum materials, which are of increasing importance in the development of flexible electronics and novel superconducting devices.