KL divergence of slab (T1) topologies relative to an infinite Universe as a function of ℓ_max with sizes and (top), and as a function of size L of the fundamental domain for various ℓ_max (bottom). A torus with , corresponding to (H₀L)^-1< 0.154, has a fundamental domain that is larger than the distance to the last-scattering surface and leaves only a small trace in the CMB. This is why the KL divergence drops rapidly at this point. Note that the information for continues to rise with ℓ_max whereas it levels off for the slightly larger case. In the lower panel we see that there is a slight feature in d_KL at about half the horizon distance, which is probably due to harmonic effects. The corresponding figures for cubic (T3) topologies look qualitatively similar except that all d_KL values are three times larger.