I was taken aback recently by some comments by Stephen Hawking as quoted in the Times:
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."It is perhaps presumptious of me to criticise Hawking on matters extraterrestrial (and who can say whether he was accurately quoted?), but this strikes me as extremely doubtful.
It is one thing for such to be a plot device in an adventure film, but to have it seriously presented by so august a personage as Hawking seems to me to call out for criticism. My question is, how (or why) is this supposed to work? That is, if we assume an alien species sufficiently advanced that they have the technology and energy for practical interstellar space travel (neither of which is trivial), how is it that they would need "the resources" of Earth? Bearing in mind, as well that those 'resources' are no different than those available on any other planet, apart from their arrangement, which would be merely a matter of applying energy and technology.
That is, the 'resources' of Earth are simply the elements present on the planet. But these are no different (at least presumably) than those present on any rocky planet in any solar system of a second-generation star. There may be unique things about the Earth, but they are in the arrangement of the elements present, not in the elements themselves. The carbon or nitrogen atoms in my body (for example) are no different than those in the Alpha Centauri system. And so there seems no particular reason why an extremely advanced alien civilization should need to plunder the Earth for those elements.
Which is not to suggest that contact with advanced alien species would be painless. It is quite possible that such contact could be not just like the contact of Europeans with Native Americans, as Hawking suggests, but like the contact of humans with the residents of a rabbit warren or ant colony when preparing to build a new skyscraper. That is: indifference, with catastrophic consequences for us humans.
But the idea of aliens coming to plunder the Earth just doesn't make sense.