Now the world-renowned scientist has some new things to say about a potential alien invasion .
“If aliens visit us, the outcome could be much like when Columbus landed in America, which didn’t turn out well for the Native Americans,” Professor Hawking told El País .
“Such advanced aliens would perhaps become nomads, looking to conquer and colonise whatever planets they can reach,” he said.
The physicist, who has suffered from motor neurone disease since his twenties, explained that the existence of aliens is beyond doubt.
“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.”
He also explained that the best chances for the survival of the human race is to find a new home on another planet.
“There’s an increasing risk that a disaster will destroy Earth,” Prof Hawking explains.
“I have so much more I want to do.”
In July, Britain’s most famous scientist helped to launch Breakthrough Listen , a 10-year, £64million project funded by US-based Russian billionaire Yuri Milner.
Mr Milner’s team will scan the skies for alien broadcast signals, searching the entire Milky Way and 100 nearby galaxies.
Professor Hawking, 73, said at the Royal Society in London: “Somewhere in the cosmos, perhaps, intelligent life may be watching these lights of ours aware of what they mean.”