New submitter Doug Otto sends word that researchers working on the ALPHA experiment at CERN are trying to figure out whether antimatter interacts with gravity in the same way that normal matter does. The ALPHA experiment wasn't designed to test for this, but they realized part of it — an antihydrogen trap — is suitable to collect some data. Their preliminary results: uncertain, but they can't rule it out. From the article: "Antihydrogen provides a particularly useful means of testing gravitational effects on antimatter, as it's electrically neutral. Gravity is by far the weakest force in nature, so it's very easy for its effects to be swamped by other interactions. Even with neutral particles or atoms, the antimatter must be moving slowly enough to perform measurements. And slow rates of motion increase the likelihood of encountering matter particles, leading to mutual annihilation and an end to the experiment. However, it's a challenge to maintain any antihydrogen long enough to perform meaningful experiments on it, regardless of its speed. ... The authors of the current study realized that [antiatoms trapped in ALPHA] eventually escaped or were released from this magnetic trap. At that point, they were momentarily in free-fall, experiencing no force other than gravity. The detectors on the outside of ALPHA could then determine if the antihydrogen was rising or falling under gravity's influence, and whether the magnitude of the force was equivalent to the effect on matter."