Here are some interesting statements from Stephen Hawking:
"I discount suggestions that UFOs contain beings from outer space. I think any visits by aliens, would be much more obvious, and probably also, much more unpleasant".
"What is the explanation of why we have not been visited? One possibility is tha the argument, about the appearance of life on Earth, is wrong. Maybe the probability of life spontaneously appearing is so low, that Earth is the only planet in the galaxy, or in the observable universe, in which it happened. Another possibility is that there was a reasonable probability of forming self reproducing systems, like cells, but that most of these forms of life did not evolve intelligence".
However, Stephen Hawking says that "aliens do exist".
He even warns us "not to talk to aliens":
Don't talk to aliens, warns Stephen Hawking:
Here is another article on Stephen Hawking's statements:
So, once again, I pose this question:
"What are UFOs?"
"Are we been deceived into believing that UFOs are physical spacecraft being piloted or maneuvered by physical, advanced, extraterrestrial beings? or are we talking about non-physical, ultra-dimensional entities who may be giving us impressions that they are materializing and de-materializing at will (or even be deceptively "posing" as representatives from advanced extraterrestrial civilizations), for purposes yet unknown to us?"
-from Norio Hayakawa