The Casmir force is antigravity, and its effects have been well-documented for over a quarter century. If only we could scale it up past the quantum level...
I would not call it anti-gravity per se. Rather a force that results from lowering the average quantum density of empty space.
When science finally admits that Einsteins work does nothing to explain gravity and inertia, and that Sakharov had the solution all along, we will be much better off.
The universe is expanding because of the pressure caused by the quantum field. Gravity is the opposite of that expansion, but all the gravity in the universe is not enough to stop it.