At the Cern particle collider in Geneva, physicists have created and trapped atoms of antihydrogen for more than a thousand seconds, it was announced recently. It might not sound like long, but it is enough time for experiments that could help answer some of the most fundamental questions in physics.

The same scientists were the first to trap antihydrogen last year when they created and held on to 38 atoms of the stuff for 172 milliseconds in a strong magnetic field. In their latest work, published in this month's edition of Nature Physics, they trapped 309 antihydrogen atoms for varying amounts of just over 16 minutes.

Jeffrey Hangst of the University of Aarhus in Denmark, who led the experiments, said that the purpose of the study was to compare antimatter with atoms of normal matter. “We've studied what's going on with these atoms while they're in the trap, how they're moving, what energy or velocity they have. With 38, that was difficult, but with 300 it starts to look like something you can make averages out of. We're getting information about how they're behaving in the trap.” Antimatter was first postulated by the British physicist Paul Dirac in 1930 while working on a way to reconcile the ideas of quantum mechanics with Albert Einstein's theory of relativity.

The question scientists want to answer is why antimatter seems to be missing from the universe. The laws of physics do not differentiate between matter and antimatter so, at the creation of the universe during the big bang, equal amounts of both should have been made. For every particle of matter in the universe, there should be a particle of antimatter. In practice, though, we do not see them. — © Guardian Newspapers Limited, 2011

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