Varying Constants of Nature: Fragments of a History

Abstract

The concept of constants of nature originated in the late-nineteenth century and has since then increasingly occupied the minds of physicists. But are the constants truly constant? Inspired by Paul Dirac’s suggestion that the gravitational constant varies slowly in time, the question was addressed not only by physicists but also by astronomers, geologists, and paleontologists. Pascual Jordan in Germany and Robert Dicke in the United States formulated theories of gravitation that went beyond general relativity by incorporating a varying gravitational constant. These theories had cosmological consequences and also implications for the earth sciences. During the period 1955–1975, theories of varying gravity played a significant role in the process that led to the plate-tectonics revolution. Although the theories turned out to be wrong, this chapter in the history of interdisciplinary science deserves attention. For one thing, it changed the landscape of both the cosmological and geological sciences. For another thing, the question of varying natural constants is still unsettled and the subject of scientific investigation. The article focuses on the period from about 1930–1975, but also includes some comments of a more general nature.