The history of cooling law: when the search for simplicity can be an obstacle

This paper presents an historical overview of the research on the cooling law, from Newton until the beginning of 20th century, and provides some suggestions for the use of this history as a resource for teaching. This history begins with a description and an interpretation of Newton’s earlier works in 1701 and an overview of studies confirming or confuting Newton’s law during the 18th century. Subsequently, it presents the early studies on cooling due to radiant heat, the fundamental work of Dulong & Petit published in 1817, and a brief overview of the research conducted after 1850 on the laws of thermal radiation and of natural and forced convection. It is shown that many scientists persisted in maintaining Newton’s law, despite numerous evidence to the contrary, by attributing the found discrepancies to empirical errors or to other disturbance factors. Many scientists considered this law as a fundamental principle rather than a conjecture to be tested by means of experiments, while others were searching for a different but general and unique cooling law. The faith in the simplicity of natural laws and the spontaneous idea of proportionality between cause and effect seem to have strongly influenced Newton and many later scientists. A discussion of epistemological, methodological and pedagogical implications is offered.