Where is antimatter?

JUST after the Big Bang, about 14 billion years ago, the universe was packed with equal amounts of matter and antimatter. Antimatter contains the same set of subatomic particles as matter but with opposite charges. Protons have antiprotons; neutrons, antineutrons; and electrons, antielectrons. When the two come in contact, they annihilate each other. Scientists do not have a definitive answer to why matter won the war and the universe is composed only of matter. But it is believed a slight asymmetry gave matter an edge over antimatter, knocking it out almost entirely.