The conception of photons - Part I

Abstract

In the year 1900, Max Planck was led by experimental observations to propose a strange formula for the intensity as a function of frequency for light emitted by a cavity made in a hot substance such as a metal. Planck provided a derivation based on peculiar properties to be obeyed by the emitters and absorbers in the cavity, introducing a new fundamental constant in the process. I attempt to point out some nuts and bolts reasoning that could have provided a clue.

In 1905, Einstein made the bold hypothesis that radiation was absorbed and emitted as packets of energy proportional to the frequency and propagated without spreading out like waves. He was able to propose a formula for the photoelectric effect based on his hypothesis. While the formula was experimentally verified by 1913, his peers seem to have rejected its interpret at ion in terms of light quanta. Einstein himself was aware of its inherent contradictions. The first part of this article goes over this period of struggle with the photon concept, and sets the stage for the entry of S N Bose’s critical contribution in 1923.