Karl Schroeder is one of the new stars of hard SF. His novels, Ventus and Permanence, have established him as a new force in the field. Now he extends his reach into Larry Niven territory, returning to the same distant future in which Ventus was set, but employing a broader canvas, to tell the story of Teven Coronal, a ringworld with a huge multiplicity of human civilizations. Brilliant but tro...