Similar to the wormhole theory, IMO they get here by going out of space. They cut out space so that the destination comes to them, not the other way round.
I've seen a UFO go from this space to "out of space" gradually and it is like a film reel where the UFO slowly goes from every frame (our space) to every two frames to every 10 frames to every 1000 frames until it disappeared.
I've seen a UFO go from this space to "out of space" gradually and it is like a film reel where the UFO slowly goes from every frame (our space) to every two frames to every 10 frames to every 1000 frames until it disappeared.