The nature of light: what are photons?

Abstract

We are told that our present understanding of physical law was ushered in by the Quantum Revolution, which began around 1900 and was brought to fruition around 1930 with the formulation of modern Quantum Mechanics. The photon was supposed to be the centerpiece of this revolution, conveying much of its conceptual flavor. What happened during that period was a rather violent redirection of the prevailing world view in and around physics - a process that has still not settled. In this paper I critically review the evolution of the concepts involved, from the time of Maxwell up to the present day. At any given time, discussions in and around any given topic take place using a language that presupposes a world view or zeitgeist. The world view itself limits what ideas are expressible. We are all prisoners of the language we have created to develop our understanding to its present state. Thus the very concepts and ways of thinking that have led to progress in the past are often the source of blind spots that prevent progress into the future. The most insidious property of the world view at any point in time is that it involves assumptions that are not stated. In what follows we will have a number of occasions to point out the assumptions in the current world view, and to develop a new world view based on a quite different set of assumptions.