The Nature of Light

The question ‘is light a ray, a wave or a particle?’ has long fascinated philosophers and has intensified since the concept of the photon first emerged at the beginning of the twentieth century. The pragmatic answer to the question is ‘it depends what you are looking for’ and is really about how best to conceptualise light in particular circumstances. We have already mentioned such distinctions briefly in Chapter 1. This chapter will extend these basic concepts to introduce the material which follows in later chapters.