Physical origin of “chaoticity” of neutrino asymmetry

We consider the indeterminacy in the sign of the neutrino asymmetry generated by active-sterile neutrino oscillations in the early universe. The dynamics of asymmetry growth is discussed in detail and the indeterminacy in the final sign of the asymmetry is shown to be a real physical phenomenon. Recently published contradicting results are carefully considered and the underlying assumptions leading to the disagreement are resolved.