Stephen Hawking Says Aliens Exist But Are Dangerous
British astrophysicist Stephen Hawking says aliens are out there, but it could be too dangerous for humans to interact with extraterrestrial life.

Hawking claims in a new documentary that intelligent alien lifeforms almost certainly exist, but warns that communicating with them could be "too risky."

He speculates most extraterrestrial life will be similar to microbes or small animals - but adds advanced lifeforms may be "nomads, looking to conquer and colonize."