  Unknown short-distance effects cancel the quartic divergence of the
zero-point energies. If this renormalization took effect in the early universe
after the last phase transition and applied only to modes whose wavelengths
(over 2 pi) were shorter than the Hubble length 1/H at that time, then the
zero-point energies of the modes of longer wavelengths can approximately
account for the present value of the dark-energy density. The model makes two
predictions.
