General Relativity as an Open Theory

Abstract

The question of the openness, or comprehensiveness, of a theory is very much related, though not identical with, certain questions that became apparent very early in the development of modern physics. It is, I believe, only an apocryphal story that when Newton first proposed his theory of gravitation and the attraction of the earth on the moon, there were objectors who said that it was absurd, when people knew next to nothing about what went on inside the earth, to pretend to be able to infer its attraction over a far distance. They felt that a knowledge of the constitution of the earth was a necessary prerequisite to the discovery of the laws of satellite motion. Nowadays we might tend to laugh at this, but, of course, there was a grain of justice in what they were saying.