Teleportation... might explain several aspects of the UFO phenomena (especially in regards to the ability of UFOs to vanish and reapper on site). In
this article on space travel and teleportation, the author of a new book on teleportation comments on its possible use by aliens:
"If indeed we are to become a space teleporting civilization, what about other advanced civilizations circling distant stars? Perhaps they have
already mastered mass transportation via teleportation?
One might even be drawn to consider that mode of travel in connection with purported UFO visitation of Earth.
"Any strange comings and goings are candidates for teleportation, although you would obviously have to eliminate all mundane explanations first,"
Darling responded. "According to reports, some UFOs do appear and disappear quite abruptly, which would fit in with the basic idea of
teleportation," he said.
Darling said that interstellar teleportation would be one way to circumvent the light barrier, "although, as we understand the process now, you would
need to make a sub-light trip first to set up the teleportation receiver and assembler at the destination."
Quantum teleportation, Darling pointed out is the kind we can do at the subatomic level in the lab today. And that requires equipment at both ends to
be able to work.
"Extraterrestrial intelligence that is thousands or millions of years ahead of us will certainly be teleportation experts," Darling advised, "if
the technology can be implemented at the macroscopic biological level."
What possible outcome, then, from ET successfully tinkering with teleportation?
"We might expect advanced aliens to be occasionally beaming in to check on our progress as a species," Darling concluded."
Personally... I think this fits in with a lot of UFO/abduction reports. Many of the most believable witnesses have so-called 'entry amnesia'
wherein they cannot remember actually entering the 'craft' through a hatch or airlock. Personal teleportation could explain this.