In the very early Universe, there were tremendous numbers of quarks, leptons, anti-quarks, and anti-leptons of all species. After only a tiny fraction-of-a-second has elapsed since the hot Big Bang, most of these matter-antimatter pairs annihilate away, leaving a very tiny excess of matter over antimatter. How that excess came about is a puzzle known as baryogenesis, and is one of the greatest unsolved problems in modern physics. (Credit: E. Siegel/Beyond the Galaxy)
You can only create or destroy matter by creating or destroying equal amounts of antimatter. So how did we become a matter-rich Universe?
Everywhere we look in the Universe, we find structure of some sort: planets, stars, gas, dust, plasma, and galaxies galore. Every indication…
