The Big Bang should have produced equal matter and antimatter. Yet, a slight imbalance—baryon asymmetry—meant that leftover matter formed the universe we know. Mechanisms may involve CP violation in particle physics. Without this tiny asymmetry, all matter would have annihilated, leaving a universe of radiation only. Research on particle accelerators and cosmology tests theories of this imbalance. The asymmetry is essential for stars, planets, and life itself.
It matters because baryon asymmetry explains why we exist.
It also connects cosmic evolution with fundamental particle physics experiments on Earth.
A tiny particle imbalance made life possible in the cosmos.
Particle Data Group [pdg.lbl.gov]