# Is there another universe which is made up of antimatter, in large amounts like ours is made up of matter?

Can it be possible that in the big bang, not one, but two universes were formed, one formed of matter, and the other formed of antimatter? It seems logical to me that since our universe is formed of matter, there must be some universe made of antimatter, so that a sort of an equilibrium is maintained. Can this other antimatter universe be treated like a mirror image to our universe, so as to maintain the equilibrium?

Actually, to me it seems a bit strange that the big bang should produce a universe with much matter and little antimatter. So it seems that there must be a universe with greater antimatter and less matter, just the mirrored image of our universe, doesn't it?

There are various theories about how the matter anti-matter asymmetry arose. See this search for lots of related questions. It's generally believed that the Big Bang formed almost equal quantities of matter and anti-matter, but there was a very small inbalance i.e. there was slightly more matter. The anti-matter all annihilated with matter to leave normal matter and lots of photons (the particle to photon ratio in the universe is about $10^{-9}$, that is a billion photons for each particle of matter).