2013/04/30 by C. Amole, M. D. Ashkezari, M. Baquero-Ruiz +35 · 1 citation
Physics and Astronomy · #Solar and Space Plasma Dynamics #Cosmology and Gravitation Theories #Dark Matter and Cosmic Phenomena
paper · pdf · doi:10.1038/ncomms2787
openalex publication_date 2013/04/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/23
Physicists have long wondered whether the gravitational interactions between matter and antimatter might be different from those between matter and itself. Although there are many indirect indications that no such differences exist and that the weak equivalence principle holds, there have been no direct, free-fall style, experimental tests of gravity on antimatter. Here we describe a novel direct test methodology; we search for a propensity for antihydrogen atoms to fall downward when released from the ALPHA antihydrogen trap. In the absence of systematic errors, we can reject ratios of the gravitational to inertial mass of antihydrogen >75 at a statistical significance level of 5%; worst-case systematic errors increase the minimum rejection ratio to 110. A similar search places somewhat tighter bounds on a negative gravitational mass, that is, on antigravity. This methodology, coupled with ongoing experimental improvements, should allow us to bound the ratio within the more interesting near equivalence regime. One intriguing question about antimatter that is yet to be directly answered is whether or not it behaves exactly the same as matter under gravity. Here, a direct experimental method is presented to measure the ratio of inertial to gravitational mass for antihydrogen under free-fall conditions.