The Age of the Earth

Abstract

WHILE reading through Dr. F. A. Lindemann's defence of Lord Kelvin's estimate of the age of the earth, I was reminded that in spite of the sympathetic spirit in which he always entered into any discussion, he would never allow the least doubt to be thrown on the correctness of his estimate of the earth's age. Yet it is open to several objections: he assumed that the solidified crust, as it was being formed, would sink toward the centre of the earth until it was solid throughout, whereas there can be no doubt about its core being so heavy that the crust material could not possibly sink. He also assumed a diminishing rate of cooling, whereas the greater portion of the earth's surface is covered by water the bottom temperature of which must have been practically constant for millions of years. He also cuts down the temperature in the earth's centre from 410,000° F., which it would be according to his assumption, to 7000° F.; whereby the available heat is reduced enormously. However, if radio-active processes can supply the earth's radiation losses there is no need to deal with the older question.