After plate tectonics

Abstract

Jordan and Dicke were not the only cosmologists who thought that varying gravity and other exotic ideas from fundamental physics might be relevant for the earth sciences. In the 1970s Fred Hoyle developed a revised steady-state model of the universe with implications for the history and structure of the Earth. In the same decade Dirac returned to his favourite hypothesis of a decreasing gravitational constant. Attempts to test the G(t) hypothesis in one of its several versions came from physics, astronomy and geology until it gradually became clear that the constant is indeed constant—as far as measurements can tell. In the same period the expanding Earth hypothesis ran out of power and separated increasingly from mainstream geophysics. The hypothesis of a smaller Earth in the past continued to be defended but without being taken seriously any longer by the majority of earth scientists.