Stephen Hawking says aliens could be as brutal as Christopher Columbus

British physicist Stephen Hawking, the brilliant man who wrote "A Brief History of Time," says aliens probably exist and frets that if they discover Earth their intentions might be less like the film, "Close Encounters of the Third Kind" and more like the book, "A Hitchhiker's Guide to the Galaxy." In the book, alien bureaucrats determine the Earth should be demolished to make way for a space highway. Sorry. Nothing personal. Prepare to die.

It's not such a crazy thought, says Hawking, in a Discovery Channel series. "To my mathematical brain, the numbers alone make thinking about aliens perfectly rational," he said.

Then, citing the example of Christopher Columbus' landing in the Americas and colonizing indigenous tribes, Hawking concluded our efforts to contact alien races may well be "too risky."

"We only have to look at ourselves to see how intelligent life might develop into something we wouldn't want to meet," he 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 colonise whatever planets they can reach."

Sounds like the Vikings. Or Romans. Or, yes, Spaniards. [Read Hawking's biography.]

Meanwhile, enjoy this trailer from the "Hitchhiker's" film...