Photon Interferences: History and Fundamental Aspects

Abstract

The discovery of the characteristics and properties of light was not straightforward. It took a long time, a lot of mistakes, hesitations, and reversals of ideas, before finally reaching a satisfactory concept of light. Many assumptions were made, based either on philosophical approaches or, more recently, on observations. We can distinguish roughly two periods. Before the work of Isaac Newton, light was not considered in and of itself, as an object. Newton had the brilliant idea to try to define light, independently of its effects. Thanks to him, the question then arose as to whether light should be defined as particles, with a defined spatial extent, or as something more vague, such as non-localized waves for example. It is this history that we summarize here, with particular emphasis on the notion of interference introduced by Thomas Young in the early nineteenth century.