GENEVA, April 30 (Xinhua) -- Researchers at CERN in Switzerland have on Tuesday published a paper in Nature Communications, describing the first direct analysis of how antimatter is affected by gravity.
"This is the first demonstrated experimental method to directly address the question of the gravitational nature of antimatter," said Jeffrey Hangst, spokesperson for the Antihydrogen Laser Physics Apparatus (ALPHA) collaboration.
Antimatter particles are the "mirror image" of normal matter, but with opposite electric charge. One significant difference between the two may be the way they interact with gravity - antimatter may be repelled by matter and "fall upwards" rather than being attracted to it.
"In the unlikely event that antimatter falls upwards, we would have to revise our view of the way the universe works," said Joel Fajans, a member of ALPHA.
But in order to study it, scientists must find a way to trap the antimatter long enough before they meet normal matter and destroy each other in what is called annihilation. ALPHA was the first experiment to trap atoms of antihydrogen - neutral antimatter atoms held in place with a strong magnetic field for up to 1,000 seconds.
"We used our position-sensitive annihilation detector to see if we could observe the influence of gravity on the released atoms," said Hangst.
The experiment will come back on line in 2014 with an upgraded antimatter trap called ALPHA-2.
"We look forward to refining it when we start up again in 2014. With more data, and perhaps atoms with even less thermal motion to compete with gravity, we hope to be able to test whether antimatter actually falls down," said Hangst.