The Connection Between Particle Physics and the Universe

Cosmologists have given particle physicists big clues to explain the universe. Dark matter is not made of quarks as atoms are, so it needs an unstable particle that lives for a microsecond. This particle has to live long enough to be with us and hold galaxies together today. There's another more subtle puzzle: why are we here? If the universe began with equal amounts of the kind of matter that we're made out of and antimatter, they all would have annihilated and disappeared.