Whitehead's theory of gravitation


In theoretical physics, Whitehead's theory of gravitation was introduced by the mathematician and philosopher Alfred North Whitehead in 1922. While never broadly accepted, at one time it was a scientifically plausible alternative to general relativity. However, after further experimental and theoretical consideration, the theory is now generally regarded as obsolete.

Principal features

argued that Whitehead's theory features a prior geometry, but this is disputed by Dean R. Fowler, since it contradicts Whitehead's philosophy of nature. For Whitehead, the geometric structure of nature grows out of the relations among actual occasions. Fowler's interpretation of Whitehead's theory makes it an alternate, mathematically equivalent, presentation of general relativity.
Under Will's presentation, Whitehead's theory has the curious feature that electromagnetic waves propagate along null geodesics of the physical spacetime, while gravitational waves propagate along null geodesics of a flat background represented by the metric tensor of Minkowski spacetime. The gravitational potential can be expressed entirely in terms of waves retarded along the background metric, like the Liénard–Wiechert potential in electromagnetic theory.
A cosmological constant can be introduced by changing the background metric to a de Sitter or anti-de Sitter metric. This was first suggested by G. Temple in 1923. Temple's suggestions on how to do this were criticized by C. B. Rayner in 1955.

Experimental tests

Whitehead's theory is equivalent with the Schwarzschild metric and makes the same predictions as general relativity regarding the :Category:Tests of general relativity|four classical solar system tests, and was regarded as a viable competitor of general relativity for several decades. In 1971, young Clifford M. Will thanks Ni Wei-To to comprehend Whitehead's theory and claims that the theory makes predictions concerning ordinary ocean tides on Earth which are in violent disagreement with observation which immediately nullified this theory. As mentioned previously, the interpretation of the theory used by Will has been criticized by Fowler, who has also argued that different tidal predictions can be obtained by a more realistic model of the galaxy. Also Reinhardt and Rosenblum criticised such statements.
In 1989, a new interpretation of Whitehead's theory was proposed that eliminated the unobserved sidereal tide effects. However, the new interpretation predicted a new, unobserved, effect, called the "Nordtvedt effect."

Footnotes