Ringworld's Children

Ringworld's Children is a 2004 science fiction novel by Larry Niven, the fourth in the Ringworld series set in the Known Space universe. It describes the continuing adventures of Louis Wu and companions on the ancient and amazing Ringworld.

The novel's plot is largely concerned with the so-called Fringe Wars. All the intelligent species of Known Space are interested in the Ringworld. In the novel (actually begun in the previous novel, The Ringworld Throne), they engage in a Cold War of sorts on the fringe of the Ringworld star system.

The novel also explores the interactions of multiple elements invented or described in previous Niven short stories or novels. For instance, two stories in the Crashlander short-story anthology consider separately the implications of a superfast hyperdrive ("At The Core") and medical nanotechnology ("Procrustes"). Although these super-technologies are seemingly unrelated, their combination is a key element of the plotline of Ringworld's Children. In another example, the ARM ships of the Fringe War (the ARM was detailed in "The Long ARM of Gil Hamilton") are powered by anti-matter and have anti-matter weapons. When asked where they most likely got it from, the Hindmost remarks that it is probably from an anti-matter solar system. This is a reference to a third short story in the Crashlander anthology that describes the discovery of the antimatter planet Cannonball Express. As in the previous two novels, the interactions of Pak protectors play an important role. And one of them has quite a tale to tell...