Do aliens exist? They do, but humans should try to avoid any contact with them -- at least, that's what one of the world's leading physicists, Stephen Hawking, claims.
The suggestions, that the extraterrestrials are almost certain to exist, come in a new documentary series for 'Discovery' channel, in which Hawking will set out his latest thinking on some of the universe's greatest mysteries.
Alien life, he will suggest, is almost certain to exist in many other parts of the universe -- not just in planets, but perhaps in the centre of stars or even floating in interplanetary space, The Sunday Times reported.
Hawking's logic on aliens is unusually simple.
The universe, he points out, has 100 billion galaxies, each containing hundreds of millions of stars. In such a big place, Earth is unlikely to be the only planet where life has evolved.
"To my mathematical brain, the numbers alone make thinking about aliens perfectly rational. The real challenge is to work out what aliens might actually be like," the 68- year-old was quoted as saying.
The answer, Hawking suggests, is that most of it will be the equivalent of microbes or simple animals -- the sort of life that has dominated Earth for most of its history.
One scene in his documentary shows herds of two-legged herbivores browsing on an alien cliff-face where they're picked off by flying, yellow lizard-like predators. Another shows glowing fluorescent aquatic animals forming vast shoals in the oceans underlying the thick ice coating Jupiter's moon Europa.
Such scenes are speculative, but Hawking uses them to lead on to a serious point -- that a few life forms could be intelligent and pose a threat.
He believes that contact with such a species could be devastating for humanity, and suggests that aliens might raid Earth for its resources and then move on: "We only have to look at ourselves to see how intelligent life might develop into something we wouldn't want to meet.
"I imagine they might exist in massive ships, having used up all the resources from their home planet. Such advanced aliens would perhaps become nomads, looking to conquer and colonise whatever planets they can reach."