2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/11539We ask whether the universe can be a patchwork consisting of distinct regions of matter and antimatter. In previous work we demonstrated that post-recombination matter-antimatter contact near regional boundaries leads to an observable (but unobserved) gamma-ray flux for domain sizes of less than a few thousand Mpc, thereby excluding such domains. In this paper we consider the pre-recombination signal from domains of larger size.6 pages, latexAstrophysicstext