One of the most common objections to UFOs-as-extraterrestrials that I see is that the distances between solar systems, and the amount of time required to travel between them is so large, even at light speed, that any such visitors are simply impossible. This objection is usually backed up with relativity, and the increasing amount of energy required as C is approached.

My objection to this is orangutans.

Orangutans are amazing creatures. Placid but intelligent, social and all in all an interesting specimen from nature. But you cannot teach them calculus. It's simply impossible. Their brains are not capable of dealing with concepts that are necessary.

What does this have to do with UFOs? There is a chance that there are concepts in the universe of which our brains are unable to conceive, just like orangutans and calculus. These concepts may be necessary to achieve travel over interstellar distances.

I understand that this is an unprovable statement. It is, nevertheless, a (admittedly fluffy) rebuttal to the "relativity forbids FTL travel" objection that is raised when the subject of UFOs is discussed. We have seen glimpses where savants are able to perform mental tasks that are amazing to "normals", giving hints that such things might at least be possible.