The supposedly "alien" incursions into our local space/time would be not impossible to navigate, seeing that their view of things are much more than our view of things. We are stationary on this planet. They are spacially travellers through the far distances that apparently hinder those travels. If a society of another race were to overcome distance discrepancies and to do so with technology applied to that goal of travel, then their technology is adaptive to the time factor of the speed of light, meaning that speed is essential to inter-galactive travel with newer more effectual crafts of travel. It is not about fiction I am talking here. It is about cracking the speed of light code and makimg a neccessary adjustment to the source of power based on fantastically innovated parameters as well as impossibly navigated speeds of intergalactic travel. I am convinced that more knowledge is required to travel in space, starting with power supplies of another sort just beyond the nuclear limitation of energy required to aquire both the speed and agility through space/time that most advocates of UFO sightings have witnessed. However that knowledge is aquired for space travel is still a mystery; the combustible energy type of energy usage is not enough for swift and correct navigation to other bodies of planets and outside visitations to other star systems. It is a matter of time and ingenuity to bring us to the same level of transport that visitors have right now in their vehicles.
That's it for me!!