I wonder why people think that UFO's are coming grom another far away planet. I think that such "alliens" have lived on earth before us (humans) or together with us for long time.
A space travel is not like going from New York to Canada in a train. Space traveling implies several consequences which will hurt the travelers. For example, staying in outer space for about a year distorts the human body, diminishes its inmune system to dangerous levels, it causes in it a faster osteoporosis, it leads to disorientation and other mental troubles, and more. If a human wants to go to a planet in another solar system with the current consequences of space traveling, what it will land in such another planet is a vehicle with a mass of flesh drop on the floor of it as jello.
So, we cannot expect that people from other planets won't have similar consequences in their traveling. Of course they will have such a problem which is matter suffering changes by the changes in their environment. The laws of physics rule over that foolish imaginations of many.
Unless you think that such alliens are not made of matter.
Star Trek is a fantasy like Relativity theory or Snow White and the Seven Dwarfs story, you just cannot lean on such fantasies to discuss the possibilities of alliens coming to earth from other galaxies.
Regardless of speed, the travelers and their machines will be indeed affected by the traveling, and we are talking of trillions of miles of traveling taking years of motion through space.
You can believe in Star Trek fantasies if that is your desire, but such fantasies won't justify at all the idea that such UFO's come from other solar systems or similar ideas.
Put your feet on earth...
