The helium abundance and the isotropy of the Universe

Abstract

Primordial nucleosynthesis in a Bianchi type I universe is investigated. The effects, caused by the anisotropic momentum distribution of the electron neutrinos, neglected in earlier investigations, are taken into account. We show that the helium abundance is a rapidly decreasing function of the present value of the shear in the Hubble flow, which is contrary to what has been previously believed.