TL;DR

Conclusion

We have searched for evidence of the effect of gravity on the motion of particles of neutral antimatter. The best fit to our measurements yields a value of (0.75 ± 0.13 (statistical + systematic) ± 0.16 (simulation)) g for the local acceleration of antimatter towards the Earth. We conclude that the dynamic behaviour of antihydrogen atoms is consistent with the existence of an attractive gravitational force between these atoms and the Earth. From the asymptotic form of the distribution of the likelihood ratio as a function of the presumed acceleration, we estimate a probability of 2.9 × 10−4 that a result, at least as extreme as that observed here, could occur under the assumption that gravity does not act on antihydrogen. The probability that our data are consistent with the repulsive gravity simulation is so small as to be quantitatively meaningless (less than 10−15). Consequently, we can rule out the existence of repulsive gravity of magnitude 1g between the Earth and antimatter. The results are thus far in conformity with the predictions of General Relativity. Our results do not support cosmological models relying on repulsive matter–antimatter gravitation.