Primordial and late-time inflation in Brans–Dicke cosmology

The basic motivation of this work is to attempt to explain the rapid primordial inflation and the observed slow late-time inflation by using the Brans–Dicke theory of gravity. We show that the ratio of these two inflation parameters is proportional to the square root of the Brans–Dicke parameter ω . We also calculate the Hubble parameter H and the time variation of the time dependent Newtonian gravitational constant G for both regimes. The variation of the Hubble parameter predicted by Brans–Dicke cosmology is shown to be consistent with recent measurements: the value of H in the late-time future is predicted as 0.86 times the present value of H .