The nearest star to the solar system is located at a distance of 4.3 light years from Earth. Even if the aircraft type "flying saucer", will move only 20 times slower than the speed of light (which is a very high speed), the flight will take about 90 years. So it is unlikely that we regularly visit ships brothers on reason.
We will figure it out eventually. Think how the world thought 30 years ago. You think they could imagine what we have today? They would say impossible too.