Nobody knows of any such thing as negative mass or anti-gravity, there’s no theoretical reason to expect that it exists, and every previous suggestion that something like it had been found was very probably a hoax. But let us know if you find some mysterious rocks that fall upwards in a vacuum.
No theoretical physical models have made any testable predictions that include an anti-gravitational effect
I think we haven’t finished studying gravity yet.
Every time we think we’re out, it just pulls us back in.
Scientists who have since studied Brown’s devices have not found any anti-gravity effect, and have attributed the noticed motive force to the more well-understood phenomenon of ionic drift or “ion wind” from the air particles, some of which remained even when Brown put his device inside a vacuum chamber. More recent studies at NASA, held at high voltages and proper vacuum conditions, showed no generated force.
Ion thrusters are real (and neat), but they are not anti-gravity tech.
Sure, but what is gravity? :D
¯\_(ツ)_/¯
