Ringworld
by Larry Niven
Summary
Louis Wu is two hundred years old, bored, and celebrating his birthday by teleporting round the Earth to stay ahead of midnight, when he is recruited by a Pierson's puppeteer: a two headed, three legged herbivore whose species fled the galaxy some time ago on general principles and whose defining characteristic is cowardice so absolute it is a professional qualification.
The crew is Louis, the puppeteer Nessus, a Kzin called Speaker to Animals from a species humanity has fought four wars with, and Teela Brown, a young woman selected because her ancestry suggests she is genetically lucky.
Their destination is an artificial ring around a distant star: a band six hundred million miles in circumference and a million miles wide, spun for gravity, with walls a thousand miles high at the rim and shadow squares orbiting inside to make night. Its surface area is three million times the Earth's. They crash on it, and the novel becomes the problem of walking far enough across an engineered landscape to find something that can lift them off.
Niven does the arithmetic in public and that is the pleasure: the physics of the ring, its meteor defence, its failure modes, and a civilisation that has fallen so far its inhabitants no longer know they live on a machine.
Teela's luck is the cleverest thing in the book. If she is genuinely lucky then nothing bad can happen to her, which means every disaster the expedition suffers is, from the universe's point of view, working out in her favour, and the implications get quietly horrible.
Around three hundred and fifty pages, brisk and driven entirely by ideas, with characterisation that is functional at best and sexual politics that have aged poorly.
Best for readers who want one enormous object explored properly, and the book every later megastructure in science fiction is answering.
Historical Context & Significance
Ringworld won the 1971 Hugo Award for Best Novel, the 1970 Nebula Award and the Locus Award.
It also produced the most famous engineering complaint in the genre's history. MIT students worked out that the ring is not gravitationally stable, and reportedly chanted the Ringworld is unstable in the corridors of the 1971 Worldcon. Larry Niven took the point and built attitude jets into the structure in the 1980 sequel The Ringworld Engineers, along with corrections to several other errors readers had sent him.
The book belongs to his Known Space future history, which runs to dozens of stories and novels. It also gave the field a permanent piece of vocabulary: any enormous artificial habitat built around a star is now described by reference to it, and the design has been borrowed by video games and films ever since.