Ringworld is Niven's most highly acclaimed book and also one of his most popular. The story has the simple quest plot structure that is the hallmark of much great science fiction and fantasy. Louis Wu, a two-hundredyear-old explorer, Teela Brown, a twenty-year-old, very lucky young woman, and Speaker-to-Animals, an ambassador to Earth from the catlike Kzinti, are recruited by Nessus, a centaurlike puppeteer, to explore the Ringworld, an enormous metal strip circling a star at ninety-three million miles. The Ringworld is one of the most bizarre yet logically designed and fully detailed worlds in science fiction. Since it is manmade it is also a remarkable feat of engineering. Part of the novel's appeal is the sense of wonder which such an object inspires in the reader. Traditional hard science fiction has always tried to instill this sense of wonder into its readers through...