Wave and photon descriptions of light: historical highlights, epistemological aspects and teaching practices

Abstract

The wave and the photon descriptions of light are discussed in connection with interference and the Doppler effect. Both phenomena can be described in terms of waves or in terms of photons. However, the two descriptions are not equivalent. While the photon description deals with a single photon, the wave one deals with the behaviour of many (enough) photons. The wave description’s predictions are in agreement with experiment only when the high number of photons used (one at a time or all together) overshadows their spatially localised interaction with the detectors. These arguments are dealt with on the basis of historical breakthroughs in the light epistemological considerations and teaching implementations.

Light is Different

“…So, in 1690 Newton ask his famous question; does light propagate as waves or as particles? Newton would claim that light is made of tiny indivisible particles, while Huygens, disagreements with Newton would counter that light is a wave that propagates on (a medium that pervade all of space), the either [3].…”

Model experiments and analogies for teaching Einsteinian energy

“…The equation E = mc 2 tells us that energy has mass, while E = hf is the energy of particles such as photons (light) and phonons (heat) that are conventionally 'massless' [6,7]. We use the phrase 'energy has mass' to describe the energymass equivalence equation.…”