It is one of the biggest mysteries of the universe, what exactly happened at the time of the Big Bang.
Scientists at CERN, the European Centre for Nuclear Research have claimed a breakthrough in the race to understand.
Our world is made up mostly of matter, but when the universe started, half of it was made up of antimatter – which has the opposite electric charge.
When the two come into contact, the result is explosive.
There are vast amounts of antimatter in Star Trek, but why it disappeared from the real universe, no-one knows.
Physicists now say they have trapped elusive antimatter atoms for the first time, keeping them for a fraction of a second before they vanished.
“Matter and antimatter when they meet, they make energy, they annihilate,” said Jeffrey Hangst, a spokesman for the CERN team. “What this experiment does now, and the breakthrough here, is to hold on to the antimatter. We have a magnetic bowl, if you will, a kind of bottle, that holds the neutral antihydrogen atoms and this is the first time that this has been demonstrated.”
Earlier this year US-based scientists also found a clue in the great antimatter mystery.
Antimatter atoms have been created routinely in the lab for years. The CERN team hope that by trapping more of them, they will be able to compare matter and antimatter – and better understand the universe.