Which novel is that from? It's been some years since I read any of Asimov's books, but the way I remember it is this: In the Robot novels, the overwhelming ma

Which novel is that from? It's been some years since I read any of Asimov's books, but the way I remember it is this: In the Robot novels, the overwhelming majority of humans live on Earth in mega cities (caves of steel) with relatively few robots, and a small minority of humans live on a few dozen (50 or so) other worlds in highly roboticized societies. These humans call themselves Spacers and have very xenophobic inward cultures. In the extreme cases, exemplified by Solaris, they shun contact even with other Spacers from their own planet and surround themselves entirely with robots. Eventually the human majority leaves Earth, because a robot following the Zeroth Law decides to irradiate Earth to force humanity to spread out in the galaxy. The humans from Earth don't take many if any robots with them and rapidly overtake robot-centric Spacer culture, which is all but forgotten (as are robots). The massive galactic human population of the Empire novels are the descendants of the humans that left Earth later, not the Spacers.