The ALPHA collaboration at CERN¹ has published a paper in Nature Communications describing the first direct analysis of how antimatter is affected by gravity.

ALPHA was the first experiment to trap atoms of antihydrogen — neutral antimatter atoms held in place with a strong magnetic field for up to 1000 seconds. The original goal of the experiment was not to study gravity, but the researchers realised that the data they had already collected might be sensitive to gravitational effects.

Current theoretical arguments predict that hydrogen and antihydrogen atoms have the same mass and should interact with gravity in the same way. If an atom is released, it should experience a downward force whether it’s made of matter or antimatter. The ALPHA scientists have retroactively analysed how their antihydrogen atoms moved when released; this has allowed them to put a limit on anomalous gravitational effects.