Question

where did all the antimatter go???​

Answer 1

All the matter and antimatter particles should have annihilated with each other since then, leaving only photons, but somehow one matter particle in a billion or so has survived to create the universe as we know it. Physicists at the BaBar experiment at Stanford in the US and the Belle experiment in Japan have now, for the first time, directly measured the amount of matter–antimatter asymmetry allowed by the Standard Model of particle physics.