Einstein-Brans-Dicke Cosmology

We studied the Einstein-Brans-Dicke cosmology in detail. The difference of the evolution of the universe is significant between Einstein-Brans-Dicke cosmology and standard big-bang model during the radiation-dominated era. The power-law evolution of the scale factor is fast enough to solve the cosmological puzzles and slow enough to avoid the graceful exit problem. However, the constraints from the satisfactory bubble distribution (beta^2>0.25) and the solar system observations (beta^2<0.002) are mutually exclusive. This suggests that this kind of inflationary model is ruled out. We also clarify the distinction between Einstein frame and Jordan frame in Brans-Dicke theory.