Wavefront reversal by nonlinear optics methods

Abstract

We present a systematic treatment of the linear theory of scalar gravitational perturbations of various matter (including baryons, cold dark matter, photons, massless neutrinos, and massive neutrino) for the Hat, open and close universes, concentrating on the treatment of the massive neutrino component which has been either ignored or approximated crudely for the nonBat universe in previous literatures. PACS numbers: 98.80.Cq, 98.70.Vc

A mechanical approach of phase conjugation

“…For low values of m (x « 1), sin X. is practically equal to sin X + x cos X and the difference between (4) and (5) gives :…”