Ringworld

Dyson's concept was a thought-construct, occasioned by the realization that a growing population invariably needs more energy; eventually we will outstrip our ability to produce energy through earth's resources. Dyson reasoned that since earth intercepts only a tiny fragment of all the energy the sun emits, a sphere with a radius of one AU (Astronomical Unit = the distance from the sun to the earth) centered on the sun would be able to 'harvest' all the energy the sun put out.

Of course, such a structure would be enormous and require an enormous amount of material, even if the sphere were only a few feet thick. The Ringworld of Niven's novels is a hoop around its star, the construct of a dying race, desperate to create not only living space, but energy interceptors. Unlike a Dyson sphere, a ring around a sun can be set spinning, which stabilizes it without the need of external rocketry, and provides a simulcrum of gravity on the inside surface.

The First Novel

Many of Larry Niven's books and stories take place in a cohesive universe he calls the Known Space series - that is, they all are in the 'same' universe, wherever they happen to fall on the timeline. Ringworld details the first expedition to the Ringworld, and what they discover there.

The protagonist is Louis Wu, a human 'everyman', if every man were a genius zillionaire. He is approached by Nessus, a 'Piersons Puppeteer' who asks him to lead the exploration of the Ringworld. He also recruits Speaker to Animals, a member of the Kzin species, and Teela Brown, another human whose importance is not at first made clear.

The Aliens

Niven populates his universe with some of the most inventive aliens in modern sci-fi. My favorites have to be the 'cowardly' Pierson's Puppeteers. These creatures were discovered by an explorer named Pierson, who thought their two heads resembled sock puppets. Puppeteers possess two independent heads with the usual sensory apparatus (eyes, nose, mouth)and three hooved legs; their brains are safely stored in the body cavity. Their main cultural driver is what humans would call 'cowardice' and what the puppeteers consider to be a reasonable caution. Their ultimate ruler is called the Hindmost, shorthand for He Who Leads from Behind, and if you were ever to meet a puppeteer out in the universe somewhere, he would be considered 'mad' by his people, since only insane puppeteers ever leave the homeworld. Insane puppeteers are very valuable, though, since their society needs explorers, traders and diplomats.

The Kzin are large cat-like aliens, who periodically launch yet another war against mankind, who they consider their natural enemies. But since they always launch a war before they've completely recovered from the last one, so far mankind has managed to keep them at bay. At the time our story starts, there has been peace between humans and Kzin for some time, and societal pressures are building among the Kzinti, yet some radicals wonder if war is worth the cost. These radicals are considered dangerous traitors to their species, but their numbers are growing. The Kzin of our story hasn't yet 'earn' the right to a name, so is known by his title. Since he's an envoy to human space, he is known as Speaker to Animals, the animals being, of course, us.

The Story

The Puppeteers, one of the most technologically advanced species in Known Space, discovers the Ringworld through a deep probe. They are naturally terrified, since such a construct is beyond even their capability. Who built it? Where are they now? Could they pose a threat to Puppeteer safety? The cost of building such a thing is enormous, although the benefits are too - millions of times the living space of a sphere the size of earth. Since it's the only Ringworld known to exist, perhaps the builders died out and the Ringworld is up for grabs? And behind it all lurks the possible involvement of the mysterious race of Pak Protectors, humanity's ancient ancestors and meddlers in our fate.

Read the novel for yourself to find out what Louis Wu (and his motley crew) discovered when they got there. Then move on to sequels The Ringworld Engineers, in which more is discovered about the creation of the Ringworld, The Ringworld Throne and Ringworld's Children.