Nucleosynthesis in power-law cosmologies

We have recently considered cosmologies in which the universal scale factor varies as a power of the age of the Universe and concluded that they cannot satisfy the observational constraints on the present age, the magnitude-redshift relation for SN Ia, and the primordial element (D, ³He, ⁴He, and ⁷Li) abundances. This claim has been challenged in a proposal that suggested a high baryon density model (ΩBh²0.3) with an expansion factor varying linearly with time could be consistent with the observed abundance of primordial helium-4, while satisfying the age and magnitude-redshift constraints. In this paper we further explore primordial nucleosynthesis in generic power-law cosmologies, including the linear case, concluding that models selected to satisfy the other observational constraints are incapable of accounting for all the light element abundances.