One of the most striking properties of the visible…

““One of the most striking properties of the visible universe is the preponderance of matter over antimatter. Although particle accelerators produce matter and antimatter in equal abundances quite routinely and there is a democratic relationship between the two, we see no antiplanets, no antistars, no antigalaxies, and there is no evidence of any antimatter in the cosmic rays that come from outside our solar system. Nor do we see any evidence of the wholesale annihilation of matter and antimatter which would erupt anywhere in the Universe where the two came into contact. Thus, for some mysterious reason, there exists a form of cosmic favouritism. The observable universe is made of matter rather than antimatter. The other thing that it most obviously consists of is radiation. Indeed, on a straight count the photons have it; for there are on the average about two billion photons of light to be found for every proton in the Universe. Since every time a proton meets an antiproton and annihilates, two photons of light are produced, we can see that a universe such as ours, possessing about two billion photons for every proton, needs to have arisen from a hot dense state in which there were on average a billion and one protons for every billion antiprotons. A billion antiprotons knock out a billion protons producing two billion photons for every left-over proton. But why should the early Universe possess such a weird skewness of matter over antimatter to start off with?””

— John D. Barrow