Fermilab Discovery Science Resources: Nine Questions

9. What happened to the antimatter?

Experiments teach us that for every fundamental particle there exists an antiparticle. The big bang and its aftermath almost certainly produced particles and antiparticles in equal numbers. However, for as far out in the universe as we can probe, our observations indicate that we live in a universe of matter, not antimatter. What happened to the antimatter? A tiny imbalance between particles and antiparticles must have developed early in the evolution of the universe, or it all would have annihilated, leaving only photons and neutrinos. Subtle asymmetries between matter and antimatter, some of which we have observed experimentally in the laboratory, must be responsible for this imbalance. But our current knowledge of these asymmetries is incomplete, insufficient to account for the observed matter domination. review.

Tevatron Experiments Research Results