http://www.msnbc.msn.com/id/36769422/
Hawking: Aliens may pose risks to Earth
Hawking: Aliens may pose risks to Earth
"We only have to look at ourselves to see how intelligent life might develop into something we wouldn’t want to meet," Hawking said. "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 colonize whatever planets they can reach.”
The 68-year-old scientist said a visit by extraterrestrials to Earth might well be like Christopher Columbus arriving in the Americas, "which didn't turn out very well for the Native Americans."