Time refraction in expanding plasma bubbles

Abstract

We consider the elementary processes associated with time refraction in non-stationary plasmas. We describe the frequency shifts of longitudinal and transverse wave propagation in isotropic plasmas, and their corresponding energy variation, which is a direct consequence of non-stationarity. We also show the appearance of reflected waves, propagating with the same (time-varying) frequency, but in the opposite direction, as a direct consequence of time refraction. The case of an expanding (or contracting) plasma bubble is discussed, and will be applied to an expanding universe, and to sonoluminescence. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.