Antimatter observed to be falling down under influence of gravity

For the first time, scientists have observed antimatter particles falling downwards due to the effect of gravity

For the first time, scientists have observed antimatter particles -- the mysterious twins of the visible matter all around us -- falling downwards due to the effect of gravity, Europe's physics lab CERN announced on Wednesday.

The experiment was hailed as "huge milestone", though most physicists anticipated the result, and it had been predicted by Einstein's 1915 theory of relativity.

It definitively rules out that gravity repels antimatter upwards -- a finding that would have upended our fundamental understanding of the universe.

Around 13.8 billion years ago, the Big Bang is believed to have produced an equal amount of matter -- what everything you can see is made out of -- and antimatter, its equal yet opposite counterpart.

However there is virtually no antimatter in the universe, which prompted one of the greatest mysteries of physics: what happened to all the antimatter?

"Half the universe is missing," said Jeffrey Hangst, a member of CERN's ALPHA collaboration in Geneva which conducted the new experiment.

"In principle, we could build a universe -- everything that we know about -- with only antimatter, and it would work in exactly the same way," he told AFP.