From Academic Kids

Ringworld is a Hugo and Nebula award-winning 1970 science fiction novel by Larry Niven, set in his Known Space universe. The work is widely considered one of the classics of science fiction literature. It is followed by three sequels, and it ties in to numerous other books in the Known Space universe.

Ringworld parameters
Radius 0.95×108 miles (~1.5×108 km)
Circumference 6×108 miles (~9.7×108 km)
Width 0.997×106 miles (1,600,000 km)
Height of rim walls 1,000 miles (1,600 km)
Mass 2×1027 kg (1.8×1024 short tons) (1,250,000 kg/m², e.g. 250 m thick, 5,000 kg/m³)
Surface area 6×1014 sq mi (1.6×1015 km²); 3 million times the surface area of Earth.
Surface gravity 0.992 gee (~9.69 m/s²)
Spin velocity 770 miles/second (~1,200,000 m/s)
Sun's spectral class G3 verging on G2; "barely smaller and cooler than Sol".
Day length 30 hours
Rotational time 7.5 Ringworld days (225 hours, 9.375 Earth days)
On Ringworld, time longer than a day is measured in falans, with 1 falan being 10 turns or 75 Ringworld days (93.75 Earth days), so 4 falans is slightly longer than 1 Earth year.

The story

In the year 2850, four explorers (two humans and two aliens) are chosen to explore a mysterious "ringworld," an enormous, artificial, ring-shaped structure that surrounds a star. The story is set in an extremely technologically advanced universe, where instant teleportation and indestructible spacecraft hulls are a reality.

The protagonist Louis Wu is a retired adventurer who has just celebrated his 200th birthday. Despite his age, he is in near peak physical condition due to advanced medical technology and boosterspice. He spends his time hopping from party to party across Earth, but secretly he has become bored with his lifestyle.

Nessus, a Pierson's Puppeteer, belongs to a more advanced species whose most notable trait is cowardice. Nessus has been sent to Earth to gather a small team to explore the Ringworld, the existence of which is unknown to most of the species in Known Space. Pierson's Puppeteers have a reputation as manipulators who use other species for jobs that might involve any risk.

Speaker-to-Animals is a felinoid Kzin, a ferocious predator species which has unsuccessfully warred with humans in the distant past. He is recruited as the mission's security chief. His persona seems to be modeled on a Japanese samurai warrior.

Speaker-To-Animals said one thing more before he turned back to his table. "Louis Wu, I found your challenge verbose. In challenging a kzin, a simple scream of rage is sufficient. You scream and you leap."

Finally, Teela Brown is a young human female whose role in the mission is not immediately clear. But Nessus doesn't do anything without a reason, and her usefulness becomes clear as the plot unfolds.

When their ship crash lands on the Ringworld, the adventurers must set out to find a way to get back into space. They cross vast distances, witness strangely evolved ecosystems, and interact with some of the Ringworld's varied primitive civilizations. They attempt to discover what caused the Ringworld's inhabitants to lose their technology, and puzzle over who created the Ringworld and why.


Niven includes a number of alien species and entertaining concepts from his other Known Space stories including:

The novel is also a send-up of fundamentalist religion; the inhabitants of the Ringworld have lost their technological prowess and now attribute the phenomena of their world to divine power. The four explorers thus encounter priests, crowd scenes, fanaticism, and so on.

However, it is the very idea of a Ringworld that seems to have most attracted readers' admiration. Niven fills the reader with a sense of awe and wonderment by describing the unimaginably large scale of the Ringworld. Even visualizing what such a massive structure would look like when viewed from its surface is a difficult but rewarding exercise.

Ringworld engineering

The "Ringworld" is an artificial ring about a million miles wide and approximately the diameter of Earth's orbit (which makes it about 600 million miles in circumference), centered about a star, and rotating to provide an Earthlike artificial gravity, with a habitable flat inner surface equivalent in area to approximately three million Earth-sized planets. Walls 1000 miles tall along the edges keep in the atmosphere. The Ringworld could be regarded as a thin slice of a Dyson sphere, with which it shares a number of characteristics. Niven himself thinks of the Ringworld as "an intermediate step between Dyson spheres and planets."

"Ringworld" has become a generic term for such a structure, which is an exemplar of what science fiction fans call a "Big Dumb Object". Other science fiction authors have devised their own variants of Niven's Ringworld, notably Iain M. Banks' Culture Orbitals, best described as miniature Ringworlds.

The construction of a ringworld remains firmly in the area of speculation, since although if such a structure was built it could indeed provide a huge habitable inner surface, the energy required to construct and set it rotating is so massive (several centuries' worth of the total energy output from the Sun) that without as-yet unimagined energy sources becoming available, it is hard to see how this construction could ever be possible.

Furthermore, the tensile strength of the material required would be on the same order as the strong nuclear force (since the artificial gravity is the same as normal gravity, the structure is comparable with a bridge with an extremely long span); nothing even remotely strong enough is known to exist in nature. In Niven's Ringworld novels, the material — which he calls scrith — is said to have been artificially produced through the transmutation of matter into the required substance. This could be produced by siphoning matter through wormholes in the time/space continuum from the inevitable Big Crunch.

Additionally, a ringworld design requires active stabilization, because it is not in inertial orbit. Though the ring itself is rotating at 1200 km/s (to approximate Earth gravity), the center of mass does not move at all. Large thrusters must be incorporated into the design to keep it centered about its star. This point gave Niven some difficulty after he published his first Ringworld novel; he was deluged with letters pointing out that "the Ringworld isn't stable" and dedicated the first sequel to a resolution of this problem. In the third sequel, Ringworld's Children he creates backplot explanations for several of the imperfections in his original design of the Ringworld — and wholly glosses over others, such as that Louis Wu is worried about his dietary intake of salt since the Ringworld possesses no saline oceans, while in Ringworld's Children, the Great Ocean is described as being saline.

To provide an approximation of the day–night cycle common to planets, Niven's Ringworld was also provided with a separate ring of "shadow squares" linked together (by "shadow square wires") in a ring close to the star, rotating at slightly faster than the Ringworld's spin, providing a lot of twilight, as well as a day-night cycle. These absorb a huge amount of sunlight energy, which is beamed to the Ringworld as its primary source of power. They are also not in inertial orbit, and must be actively stabilized as well. The shadow squares provide another of the imperfections "clarified" in Ringworld's Children, as five shadow squares of greater length, orbiting retrograde would provide a better day-night cycle, with less twilight.


In the first edition of Ringworld, the Earth rotates in the wrong direction.

Sequels and adaptations

The novel Ringworld has been followed by three sequels, The Ringworld Engineers (1980), The Ringworld Throne (1996), and Ringworld's Children (2004).

In the 1980s a role-playing game based on this setting was produced by Chaosium named RingworldRPG.

Tsunami Games released two adventure games based on Ringworld, "Ringworld: Revenge of the Patriarch" in 1992 and "Return to Ringworld" in 1994.

The Sci Fi Channel is reported to be developing a Ringworld miniseries [1] (http://www.cinescape.com/0/editorial.asp?aff_id=0&this_cat=Television&action=page&type_id=&cat_id=270355&obj_id=41212). There have also been reports of a movie in the early planning stages, with rumors circulating that James Cameron might direct [2] (http://filmforce.ign.com/articles/306/306997p1.html).

The plot of the first-person shooter Halo for the Microsoft Xbox also takes place on a ringworld-like structure. Given its dimensions (10,000 kilometers in diameter) it is more like Banks' Culture Orbitals than Niven's behemoth.

See also

External link

es:Mundoanillo fr:L'Anneau-Monde


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