Harkins, Perrin and the Alternative Paths to the Solution of the Stellar- Energy Problem, 1915-1923

摘要

The idea that gravitational potential energy could, through slow contraction, be the source of the energy radiated by the Sun originated with John James Waterston (1811-83) as early as 1845. Initially ignored, the idea was revived by Hermann von Helmholtz (1821 -94) in 1854, and was rapidly endorsed and popularized by William Thompson, Lord Kelvin (1824-1907) throughout the second half of the nineteenth century. A gravitational origin for the energy emitted by the Sun fitted well with the central idea embodied in the nebular hypothesis, namely that stars were the product of the gravitational contraction of a diffuse nebula. However, the reservoir of gravitational energy could provide for the solar luminosity only for a limited time, the so-called Kelvin-Helmholtz timescale that is of the order of 20 million years. By the end of the nineteenth century, it had become clear that the elegant and conceptually simple idea of a gravitational origin for the Sun's heat was in conflict with the increasingly long timescales being imposed by geologists and cosmogonists alike. The Kelvin-Helmholtz idea had become, in Eddington's words, an "unburied corpse".