One of the great mysteries of modern physics is why antimatter did not destroy the universe at the beginning of time.

To explain it, physicists suppose there must be some difference between matter and antimatter - apart from electric charge. Whatever that difference is, it's not in their magnetism, it seems.

Physicists at CERN in Switzerland have made the most precise measurement ever of the magnetic moment of an anti-proton - a number that measures how a particle reacts to magnetic force - and found it to be exactly the same as that of the proton but with opposite sign. The work is described in Nature.

"All of our observations find a complete symmetry between matter and antimatter, which is why the universe should not actually exist," says Christian Smorra, a physicist at CERN's Baryon-Antibaryon Symmetry Experiment (BASE) collaboration. "An asymmetry must exist here somewhere but we simply do not understand where the difference is."