Dirac's continuous creation cosmology and the temperature of the Earth

Abstract

DIRAC^1,2 has modified his earlier cosmological model based on the large number hypothesis^3,4, that the observed approximate equalities are not accidental but causal—even though we are as yet unaware of the nature of the relationship between cosmology and local physics (e is the electronic charge, G the gravitational constant, c the velocity of light, ρ the mean density of the Universe, H Hubble's constant and m an atomic mass). In the earlier version, Dirac assumed mass conservation and that equalities (1) held for all time, thus where R(t) is the cosmological scale factor, H = R/R. In the modified version, Dirac argues (unconvincingly in my view) that R(t) ∝ t, in which case that is, matter is continuously created such that ρ₀ ∝ t² where t is the age of the Universe. This newly created matter could be produced uniformly throughout space, or locally in proportion to the amount and composition of matter already present. Dirac prefers the second alternative, but we shall show that this leads to an unacceptable past temperature for the Earth.