A Look at the Abandoned Contributions to Cosmology of Dirac, Sciama and Dicke

TL;DR

This paper revisits the contributions of Dirac, Sciama, and Dicke to cosmology, proposing a unified model with variable speed of light that aligns with their ideas and addresses classical cosmological problems.

Contribution

It integrates Dirac's, Sciama's, and Dicke's ideas into a cohesive cosmological model with a variable speed of light, challenging standard expansion concepts.

Findings

Dicke's VSL theory aligns with classical tests of GR.

The model satisfies Dirac's second large number hypothesis.

Cosmological redshift explained by rod shortening, not expansion.

Abstract

The separate contributions to cosmology of the above researchers are revisited and a cosmology encompassing their basic ideas is proposed. We study Dirac's article on the large number hypothesis (1938), Sciama's proposal of realizing Mach's principle (1953), and Dicke's considerations (1957) on a flat-space representation of general relativity with a variable speed of light (VSL). Dicke's tentative theory can be formulated in a way which is compatible with Sciama's hypothesis on the gravitational constant G. Additionally, such a cosmological model is shown to satisfy Dirac's second `large number' hypothesis on the total number of particles in the universe being proportional to the square of the epoch. In the same context, Dirac's first hypothesis on an epoch-dependent G-contrary to his prediction- does not necessarily produce a visible time dependence of G. While Dicke's proposalreproduces the classical tests of GR in first approximation, the cosmological redshift is described by a shortening of measuring rods rather than an expansion of space. Since the temporal evolution of the horizon R is governed by \dot R(t) =c(t), the flatness and horizon problems do not arise in the common form.