Matter/antimatter Asymmetry

Most recent answer: 04/11/2012

Please forgive me if my question is stupid, as I'm only 14, but I've read that the big bang created equal amounts of matter and antimatter, so wouldn't it all just annihilate and we'd be left with a ton of subatomic particles? Also, how do nuclear fission and fusion "create" energy, when all you are doing is seperating/combining elements? They really need to give us better science books in school...
- Stephenson (age 14)
Knoxville, TN, USA
Those are both great questions. I'll start with the easier one, the second.

Nuclear reactions don't create energy. They just convert energy from one form to another.  The ones that seem to release energy start off with a lot of energy in a quiet form, as rest mass, and convert some of it to more violent forms, including light rays and fast motions of particles.

We don't fully know the answer to your other question. Some processes involving what's called the "weak nuclear force" happen differently to matter and antimatter. When the universe is changing rapidly those processes can leave more matter than antimatter. (Sakharov was the first to notice this possibility.) Although we know that the universe changed very rapidly after the Big Bang, the details of the earliest stages aren't yet known well enough to understand how the full matter-antimatter imbalance got going.

Mike W.

(published on 04/11/2012)