Corpuscular Theory

Sir Isaac Newton (1672), building on an idea suggested earlier by Descartes (1637), proposed the corpuscular theory: light consists of tiny, essentially massless, perfectly elastic particles called corpuscles, emitted by a light source; because the corpuscles are so small, a source does not lose appreciable mass even after emitting light for a long time, and their very high speed makes them effectively unaffected by gravity, travelling in straight lines through any medium of uniform refractive index. The kinetic energy of these corpuscles was taken to be the energy of the light, with the corpuscles striking the retina producing vision, and different corpuscle sizes explaining different colours. Reflection was explained as repulsion of the corpuscles by the medium, and refraction as attraction. This theory could not explain why light trave …