The observational tests of gravitation theory

Abstract

From 1918 until early 1960 the three well-known tests of relativity theory could only be made on astronomical bodies, and a great deal of work has gone into these observational problems. I have been asked to give now some account of the findings of these tests to date, including of course the laboratory measures of the red shift in 1960 which marked an epoch in the history of this subject. The ‘crucial phenomena’, as Eddington called them, are very well known: the advance of the perihelion in planetary motion, the deflexion of a light ray as it passes close to a massive body, and the red shift of spectrum lines in regions of high gravitational potential; I will discuss them in that order.