in order to improve the efficiency of their computing, ETCs will migrate outwards from their original location to the cold outer reaches of the Galaxy. They’ll move from a “galactic habitable zone” to a “galactic technological zone”—and the galactic rim will be home to a collection of individual, highly advanced “city states”. The reason we don’t see advanced civilizations in our neighborhood is because they, or their computers, find it intolerably hot here.