Given the fact there are purported to be hundreds of billions of galaxies out there, it is likely that there are other advanced civilizations. Yet given the enormous distances and the laws of physics (speed limit of 186,000 miles per second) and the nearest “habitable” alien planets hundreds of light years away), it is a virtual impossibility for a mechanical or biological entity to reach us or us to reach them. For UFO’s to be really alien craft, someone has to prove Einstein to be wrong.
I happen to believe that these UFOs are not likely to be aliens. Impossible? Of course not. It depends on one's assumptions on distributions of intelligent civilizations. We really don't know. There could be an intelligent civilization in each star system for all we know.
Yet given the enormous distances and the laws of physics (speed limit of 186,000 miles per second) and the nearest “habitable” alien planets hundreds of light years away), it is a virtual impossibility for a mechanical or biological entity to reach us or us to reach them.
We don’t have the technology to travel interstellar distances, but they might. Consider how advanced our technology would look to a person from say the 1700s. What technologies might be uncovered 300 years beyond our own time? Not hard to imagine another planet that might be 300 or 3,000 years more advanced than we are technically.
What is 100% true is that we do not fully understand our universe. To ascribe impossibility to something in the face of wide evidence is foolhardy.
It's obvious that we are tiny beings looking through a keyhole, seeing and interacting with a tiny slice of reality.
“someone has to prove Einstein to be wrong.”
See: James Clark Maxwell (1831-1879) - who postulated that distance does not really exist (one of the 194 field equations thrown out by Heaviside); the remaining four equations Heaviside converted to vector equations and so gave us all we know of the electromagnetic spectrum - without Maxwell, Einstein would have remained obscure and Tesla would never have invented alternating current.