The Historical Development of Science. I. - Heat

Abstract

Although, like many lower forms of life, we could live and have lived without any understanding of the nature of beat, without any idea as to how to control or bow to employ it, yet the advance of civilisation can be traced along the lines of our gradual acquirement of the knowledge of how to utilise available heat energy. All the heat we use comes from the sun. Glancing briefly at our storehouse of heat, it will be interesting, since this is an historical study, to go back to the very beginning of our earth. Some two thousand million years ago, for reasons into which we need not enquire here, our earth, accompanied by a number of brothers and sisters (the planets) and a vast host of unimportant cousins (the asteroids) left the sun and shortly afterwards settled down and set up home in a highly desirable and convenient orbit in which we now move round the sun. We brought with us a big supply of heat energy, which we dissipated at a really alarming rate until we established a surface crust which acted as a blanket to the rest of the contained heat energy, so that it now escapes but extremely slowly from the intensely hot material below the crust. So extremely slowly, in fact, that if we depended on it alone for warmth we could not possibly exist, and the whole world surface would sink back to a state of incredible cold. There is one other local immediate supply of heat - the radioactive materials in the surface layers of the earth's crust, which give off heat energy as they break down into less complex atoms. This source of energy also is negligible as a supply for us. All our immediate supplies of heat energy come as radiations from the sun - the earth warming up whilst the sun shines, and radiating most of that energy away again into space. The waste here is incredible ; if the solar energy were completely cut off from the earth for a few days, life would be impossible.