John Frederick Nye. 26 February 1923—8 January 2019

John Nye was an internationally renowned physicist who made fundamental contributions to the understanding of crystals, ice and light. He explored defects in crystal structures, in particular continuous distributions of dislocations. He explained the mechanics of the flow of glaciers: their advance and retreat, and how this depends on the underlying topography; and how water flows beneath and within them. He was a pioneer in the study of optical singularities on three levels: stable caustics in geometrical optics; phase singularities (wavefront dislocations) in scalar waves; and lines of circular and linear polarization in electromagnetic fields.