Symmetry Magazine provides 60 second explanations of a series of physical phenomena, including the Acceleration of Particles, the Higgs Boson, superconductors, even The Standard Model, and much more. On CP Violation:
Are the laws of nature the same for matter and antimatter? Physicists use the term “CP” (for “charge parity”) to talk about matter-antimatter symmetry. If nature treated matter and antimatter alike, then, in physics-speak, nature would be CP-symmetric. If not, CP is violated.
Experiments have shown that nature’s weak force—which is responsible for the decay of particles—does in fact violate CP. Yet CP violation poses a mystery.
The big bang should have created equal amounts of matter and antimatter, with subsequent annihilation leaving neither behind. And yet, the observable universe has about ten billion galaxies that consist entirely of matter (protons, neutrons, and electrons) with no antimatter (antiprotons, antineutrons, and positrons). Very soon after the big bang, some forces must have caused the CP violation that skewed the equality in the number of matter and antimatter particles and left behind excess matter.