The ALPHA-g experiment, the hunt for gravitational dipoles and the quantum vacuum as the source of gravity in the Universe

More recently, the ALPHA-g experiment has shown that antiatoms fall in the Earth's gravitational field like ordinary atoms, with the open possibility that antiatoms fall with a slightly lower acceleration. A possible lower acceleration of antiatoms (which could be revealed with two orders of magnitude higher precision measurements) would be an epoch-making discovery and a window to a new physics, suggesting among other things that quarks and antiquarks have gravitational charges of opposite sign. If gravitational charges of opposite sign exist, it implies the existence of virtual gravitational dipoles in the quantum vacuum, and opens up the possibility of including the quantum vacuum as an important source of gravity in the Universe.