Avatars of a Matter-Antimatter Universe

Abstract

An elegantly symmetric Universe, consisting of large islands of matter and antimatter, is by no means obviously out of the question. I review the observations that lead to the usual prejudice that the Universe contains only matter. I discuss recent work inferring that this prejudice can be converted into an inescapable conclusion. I argue that our theoretical conviction should not discourage direct searches for antimatter in cosmic rays.

arXiv comment15 pages, 5 Postscript figures. Based on a talk at the Jan. 1998 Moriond Meeting at Les Arcs, France