Title: Was Einstein Wrong
Author: Leigh Bienen
Publisher: Princeton Alumni Weekly
Issue: April 21, 1971, pp. 10-11
Description: Introductory essay to the work of Professor Robert H. Dicke in the Princeton Department of Physics from 1971. A Princeton professor challenges some established theories of gravity.
FOR the past ten years, Professor Robert Dicke ’39 and his colleagues at Princeton and elsewhere have been devising tests for the scalar-tensor theory of gravitation. The scalar-tensor theory is a modification of Einstein’s theory of general relativity. In 1965, 1967, and 1970 there were several journalistic flurries about one or another of the experiments concerning the theory. This search for experimental verification has involved Dicke in investigating the shape and composition of the sun, in projects which have ended with putting instruments on the moon, and in speculations on the origins of the universe.
The scalar-tensor theory does not attempt to replace general relativity. Rather, it supplements general relativity with a second gravitational effect. In general relativity, the strength of gravitation is constant in space and time. According to scalar-tensor theory, the strength of gravitation weakens with time.
There have been a number of papers published on the subject of the theory since its first, dramatic appearance in an article by C. Brans and Dicke in The Physical Review in 1961. Partly, this is so because relativity is a glamorous subject. Most of the papers address themselves to formal theoretical problems concerning the statement of the scalar-tensor theory. And Dicke himself published a different form of the theory a year after the original published version.
The name scalar-tensor refers to the character of the fields which are used in the theory to describe gravitation. An example of a scalar field is air pressure in a room. Every point in the room has a definite, measurable pressure. An example of a tensor field would be something like stress in the earth’s surface, or the stretching of a piece of rubber. But even these three-dimensional analogies are misleading because both of these fields, the scalar and the tensor, exist in four-dimensional space with time as the fourth dimension.
Using a scalar to express gravitation goes back to Newton. The representation of gravitation by means of a tensor…