The interference of polarised light

This article brings out a remarkable contribution to the understanding of light, made by S (for Sivaramakrishnan) Pancharatnam, when he was a doctoral student working on the optics of crystals with C V Raman at the Raman Research Institute (RRI) in Bangalore in the 1950s. We will first illustrate this contribution by means of specific examples, which already calls for considerable background, and then go on to place the work in a wider context.     

Hamilton’s optics

Building on work by Fermat and Huygens, Hamilton transformed the study of geometrical optics in his very first paper, presented when still in his teens. His ‘characteristic function’ was an analytical way to describe wavefronts, and in his hands a powerful tool to look at families of rays rather than isolated ones. His prediction of internal and external conical refraction in some crystals and its spectacular verification in a few months established his reputation among his contemporaries. This formulation of optics uncovered many general properties, not easy to see in the conventional method of tracing individual rays. The deepest outcome of his early optical work was a parallel view of the mechanics of particles, which played a fundamental role in the birth of quantum mechanics and continues to be the standard framework for classical mechanics up to the present time.     

John Archibald Wheeler

John Archibald Wheeler was a researcher and teacher par excellence who was responsible for popularizing the theory of general relativity amongst the academics in the United States. This article tries to provide glimpses of his contributions to gravitation as also some of the work of his distinguished students.