Aliens could be too frightened to make contact with the human race.
Aliens could be frightened of making contact with humans
Expert Professor Frederick Walter says there is a "100 per cent chance" of other forms of life existing elsewhere in the universe but suggests that a fear of the unknown has prevented extraterrestrials from emerging.
Professor Walter, a galactic astronomer at Stony Brook University in New York, said: "It could be that the universe is teeming with life but everybody's hiding because we're scared.
"You have no idea if other civilisations are friendly or hostile and remember, you're the new kid on the block.
"They've been around for thousands of years and are probably much more advanced, you don't know what to expect so the safest thing is to remain silent."