Chapter 10: Long Wavelengths

The wavelengths examined in the previous chapters reentered the effective horizon right after the end of inflation or during the radiation dominated stage of expansion. In this chapter (see Fig. 10.1), we analyze the longest wavelengths of the spectrum, namely the ones crossing the comoving Hubble radius during the matter-dominated stage of expansion or even when dark energy is already dominant. The physical situation discussed in this chapter is concisely summarized by Fig. 10.1 illustrating the wavelengths labeled by 2 and 3 in Fig. 8.4…