I can only conclude that Hawking has never seriously thought about it. There are NO galactic faring civilizations. If there were, they would be here now. I remember reading somewhere that it would take an expansionist civilization 10 million years to populate the galaxy. Given that the age of the galaxy is somewhere around 13 billion years, it is improbable that the first galactic civilization is on its way but hasnt reached here yet.
How about a nearby civilization, about our age? Charles Stross has done an analysis of the economics of star flight and came to the conclusion that interstellar travel makes no sense at all. http://www.antipope.org/charlie/blog-static/2007/06/the-high... It may not be possible at all.
I think that the idea that another civilization would want us for out resources is silly, for economics alone. If they wanted to leave their star because it was about to collapse into a white dwarf, there are better places to go. Any nearby M class star would have the resources to rebuild a civilization. The comet an asteroid belts can supply the materials without the problems of a deep gravity well like the earth.
How about a nearby civilization, about our age? Charles Stross has done an analysis of the economics of star flight and came to the conclusion that interstellar travel makes no sense at all. http://www.antipope.org/charlie/blog-static/2007/06/the-high... It may not be possible at all.
I think that the idea that another civilization would want us for out resources is silly, for economics alone. If they wanted to leave their star because it was about to collapse into a white dwarf, there are better places to go. Any nearby M class star would have the resources to rebuild a civilization. The comet an asteroid belts can supply the materials without the problems of a deep gravity well like the earth.