@Pythagorean,
I think it would be arrogant to assume that in the vastness of the universe, that we are the only inhabited planet.
If we are to theorize that there is 1 inhabited planet for every million galaxies, and the universe is infinite, then there are infinite numbers of inhabited worlds out there.
If we are to theorize
that there are half of that; equalling a number we can comprehend, like a billion just for the sake of easier math...then we would be incredibly arrogant to assume that our limited method of space travel is superior to the other billion worlds that may have established themselves as technologically advanced worlds.
If we continue to use one billion worlds as a basis for our theory; we can also predict that at least .0000000001% of these worlds would ahve discovered a method of space travel to reach us by now.
That would mean that one world has found us.
One world out of a billion, which is an incredible underestimate of the actual number of possible worlds that may actually know we exist.
As for the reported UFO crashes through the years; it would be silly to think that a civilization would have the technology to pass galaxies in a craft, only to crash here.
They would certainly have a reliable method of landing, if so much resources were involved in getting here.
No rational being on any planet would consider having second-rate landing capabilities on something that would undoubtedly involve a vast amount of risk.
I guess we'll only know when we're ready to know.
Good topic choice, Pythagorean.