After much talking to myself about science I don't understand, I conclude that antigravity simply can't happen, and anyone who tries is liable to cause a supernova, annihilate the planet whose gravity they were trying to escape, and form a black hole to suck any hope of reality out of this science fiction.
But what if someone didn't know that but were tricked into it by a malevolent albeit scientifically sound extraterrestrial force?
So what is some actually feasible technology a slightly-more-advanced-than-us civilization could deploy to give the shock and awe of an alien invasion in order to seal the deal?
Robots powered by solid state batteries deployed by properly-aerodynamic spaceplane landing craft ferried by orbit-built starships powered by thorium breeder reactors?
Would they be able to traverse a wormhole that was created by a failed antigravity experiment that just happens to rematerialize here? Or would that be too much creative license? I have autism so I want this to appear real as possible.