Still I don't understand the meaning of the re-entry of perturbations in the horizon. OK, I understand the shortening of the Hubble radius opposite the length scales during inflation and the extension of the horizon after inflation. But what happened in the time after inflation till the re-entry? According to me fluctuations and oscillations were there all the time, most papers discuss the perturbations in the very early time. So I don't understand the special meaning of re-entry which happened much later, at least that is what I understand.