One thing I don't understand: wasn't there just discovered a ring of antimatter circling around the Earth? Wouldn't it just disperse into space if antimatter caused antigravity? Stupid question, I know, but just something that's beyond my comprehension.
No, those are charged particles interacting with the magnetic field of the earth. Gravity is such a ridiculously weak force that you can safely ignore it in situations like that.
Tiny amounts of antimatter were just discovered circling around Earth. The anti-grav effect on the antimatter particles is swamped by the effects of the Earth's gravity and magnetic field.
According to this theory, it would be the magnetic field alone--not the gravitational field--that is overwhelming the antigravity effect. After all, if these particles had an opposite "gravitational charge", then their experience of gravity wouldn't be attractive but would be equal in magnitude but opposite in orientation. Hence "anti"gravity.
