The Problem of Heat Radiation

Abstract

This chapter summarizes the problem of heat radiation in the second half of the nineteenth century. For most physicists, this problem amounted to finding the explicit form of the radiation law. In the first phase, experimental research and general thermodynamical arguments imposed some constraints on the form of this law. One of the great conundrums of the final decades of the nineteenth century was to discover a plausible derivation of the exponential term revealed by the experiments. Here, I pay special attention to Wien’s research program. Wien combined electromagnetic theory, kinetic theory, and thermodynamics in a very creative—and sometimes opportunist—manner. More importantly, for Wien the black-body problem was a window on the study of more intricate forms of interaction between radiation and matter. Planck’s program, as we will see in the next chapters, had a totally different agenda.