Constraints on cosmic electric charge asymmetry and neutrino charge from the microwave background

We point out that an overall electric charge asymmetry in the universe will generate an anisotropy in the cosmic microwave background radiation (CMBR) via the Sach-Wolfe effect. From this, an upper limit on the electric charge asymmetry over a cosmological scale is found using the COBE data, which implies ΔTT ≤ 10−4 for the CMBR. The same argument constrains the charge of degenerate neutrinos.