They're Not Gonna See This Coming
Stephen Hawking on the alien menace:
He suggests that aliens might simply raid Earth for its resources and then move on: “We only have to look at ourselves to see how intelligent life might develop into something we wouldn’t want to meet. 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.”
I never thought I'd live long enough to see Hawking channel Roland Emmerich.