Famed British scientist Stephen Hawking is warning us that alien contact might not be the best thing. Hawking acknowledges that aliens could very well exist, but contact with Earth could bring devastating consequences. On the probability of alien life existing, he says: "To my mathematical brain, the numbers alone make thinking about aliens perfectly rational."
"Such advanced aliens would perhaps become nomads, looking to conquer and colonise whatever planets they can reach," warned Stephen Hawking. "If aliens visit us, the outcome would be much as when Columbus landed in America, which didn't turn out well for the Native Americans."
Threats would not just be from attack. The aliens could carry diseases that Earthlife would be succeptable to.
Mankind has already made a number of attempts to contact extraterrestrial civilisations. The history of humanity's efforts to contact aliens stretches back some years. The US probes Pioneer 10 and 11 were launched in 1972 and 1973 bearing plaques of a naked man and woman and symbols seeking to convey the positions of the Earth and the Sun. Voyager 1 and 2, launched in 1977, each carry a gold-plated copper phonogram disk with recordings of sounds and images on Earth.