Particle physicists have found a clue as to why the universe is made of matter rather than antimatter. Researchers at the Fermi National Laboratory near Chicago have seen what they think is a slight asymmetry in the behaviour of matter and antimatter in particles called B-mesons.
Previously, the phenomenon had only been seen in neutral kaons.
Ken Peach, head of particle physics at the Rutherford Appleton Laboratory near Oxford, said: "This is a sign of things to come. We are learning something new about one of the more mysterious aspects of the standard model of particle physics."