|Big Bang matter/antimatterPage 2 of 2 (1, 2)|
|These are fundamental unsolved questions of science. What was there before the big bang, why is there more antimatter than matter. No one knows yet. |
Standard theory says there should be equal amounts of matter and antimatter in the universe, why that isn't true is a mystery. There is some unknown asymmetry yet to be discovered.
As for what happens to the energy from the annihilation, it either creates gamma rays as photons or other anti-particle pairs. In the early universe, after the initial quark-guon plasma cooled down enough for hadrons and leptons to form, along with their anti-particle counterparts, the resulting annihilations formed photons. The photons bounced around and interacted with the protons and leptons still around until the universe cooled enough to allow the protons to bind with neutral particles to form atoms. In this state they could no longer interact with the photons readily and this allowed the photons to roam freely. Since theory states that photons are fundamental particles ,they never decay, so these same photons are still zipping around out there, but since the universe has expanded they are now weaker and less energetic, since the same photons now fill up a much larger space. This makes up what we call the cosmic microwave background. It was maybe a little oversimplified, but that's basically the gist of it.