Neutrino Degeneracy and Chemically Inhomogeneous Universe

A possibility that the universe may be strongly inhomogeneous chemically, while very smooth energetically, is considered. A possible mechanism which could lead to such a picture is a large and inhomogeneous lepton asymmetry. The model may explain possibly observed variation of primordial deuterium by an order of magnitude and predicts helium-rich and possibly helium-poor regions where the helium mass fraction differs from the observed 25% by a factor of 2 in either direction. Helium variation can be observed by a different dumping rate of CMB angular spectrum at small angles at different patches of the sky.