Some Properties of Electromagnetic Radiation

Abstract

Ever since the days of Newton and Huygens—that is, since the latter part of the seventeenth century—there have been two fundamentally different theories concerning the nature of light. Newton proposed a corpuscular theory of light without specifying definitely the nature of these corpuscles; Huygens proposed a wave theory to explain exactly the same phenomena that were explained by Newton in his corpuscular theory. In one important case, that of the velocity of light in material media, deductions from these two theories led to divergent results. On the basis of Newton’s corpuscular theory, light should travel faster in the denser medium, whereas on the basis of the wave theory light should travel slower in the denser medium. It was not until the middle of the nineteenth century that the velocity of light in a dense medium (water) was determined by Foucault and Fizeau and found to be less than that in a vacuum. By this time the wave theory had become fairly well established, mainly because of the work of Young, Fresnel, and Arago on the phenomena of interference and diffraction of light. Further, the polarization of light by reflection and by double refraction through crystals could be explained on the assumption that light waves were transverse waves. The wave theory of light was the only one that could explain satisfactorily all the optical phenomena then known.