Across the universe

Stephen Hawkings recently said that any space aliens we are likely to encounter would be nomadic in nature. They will be traveling through interstellar space, going from one galactic replenishment opportunity to the next. It’s best that we avoid contact with them, he says. Extraterrestrials, arriving on Earth, would lead to a scenario not too unlike Christopher Columbus landing in the new world. As I recall, it did not go well for the indigenous people of the new world. Apparently Dr. Hawking believes that self-preserving behaviour is selected for by evolution across the universe, as it is here on Earth. I, on the other hand, do not have a clue.