Ringworld - Larry Niven
The artefact is a circular ribbon of matter about six hundred million miles long and more than ninety million miles in radius, with a surface area three million times that of Earth. This is the Ringworld.Pierson's puppeteers, the strange, three-legged, two-headed aliens who discovered it, are understandably apprehensive of a meeting with the builders of such an immense structure and set about putting together a team to explore it. Louis Wu, a two-hundred-year-old human adventurer, Speaker-to-Animals, a kzin, an alien rather like an eight-foot-tall, red-furred cat, and Teela Brown, another human, genetically engineered for good luck, are recruited by Nessus, a mad puppeteer, to travel the two hundred light years with him and investigate. But the mission goes disastrously wrong when their ship crashlands on the vast edifice and the crew faces a daunting trek across tens of thousands of miles of the Ringworld's surface to a possible point of rescue.
About the Novel
Ringworld is a Hugo and Nebula award-winning 1970 science fiction novel by Larry Niven, set in his Known Space universe and considered a classic of science fiction literature. It is followed by three sequels, and ties into numerous other books set in Known Space.
The novel opens in 2855 with Louis Gridley Wu stepping out of a transfer booth, a teleportation kiosque, in Beirut, thus entering yet another time zone. Louis, after having escaped the festivities of his own 200th birthday, is now bar-hopping the world, always staying behind the local midnight in order to extend his birthday as long as possible.
Despite his age, Louis turns out to be in perfect physical condition owning to a combination of advanced medical technology and boosterspice, a drug that extends human life. However, though healthy, rich and intelligent, it is becoming clear Louis is utterly bored. Having lived for two centuries, he has seen it all many times over and people in general are getting on his nerves. Between transfer booths he considers another sabbatical — a trip to and beyond the reaches of Known Space, all alone in a single ship for a year or more, until he begins to yearn for people's company again — when all of a sudden the transfer booth materializes him in an sunlit hotel room, rather than the nocturnal Seville he had set its control for. Facing him is a alien with three legs, no arms and two heads.
The alien introduces himself as Nessus and Louis recognizes him for a Pierson's Puppeteer, a species that had the most advanced technology in Known Space but vanished from the region before Louis was born. Being descended from herbivorous herd animals, their morality is essentially based on cowardice. Puppeteers that display any signs of bravery are considered insane by their peers, and in fact are insane since this bravery is accompanied by other symptoms of mental illness, such as manic-depressive cycles. With aliens being potentially dangerous, space ships exposed to vacuum and their being distrustful of faster-than-light space travel, only a "brave" (insane) Puppeteer would leave home and go to a planet like Earth. These ones are in turn are still mostly cowards by human standards, so Nessus has been ordered to hire three mercenaries to do the things he himself dare not. Louis is on top of his list of candidates.
With Nessus being secretive about the mission, Louis is reluctant to join, but when the Puppeteer eventually shows Louis a blurry picture of a distant star with a ring around it, the bored Louis immediately signs up: this ring turns out to be the Ringworld, an artificial circular strip of world with spin for surface gravity, orbiting the star. The Puppeteers, being on the run from the galaxy, have spotted this artifact in their path and being cowards, the sheer power of whatever has created such a structure frightens them profoundly. Hence, Nessus' mission is to assemble a team, visit the Ringworld and see whether it poses a threat to his species. Payment to the expedition's members will be the Long Shot, the extremely fast ship depicted in the story At the Core, that Beowulf Shaeffer rode to the galactic core and back, centuries earlier.
Eventually the team is assembled. The third member, Speaker-to-Animals (Speaker) is a Kzin, a ferocious felinoid predator species which has, in the recent past, fought a series of brutal wars with humanity, eventually losing every time because of a tendency to attack before being quite ready. The Kzin who is a translator, a low-ranking official at the Kzinti embassy to Earth, reckons obtaining the Long Shot for the Kzinti Empire is enough of an achievement to (literally) give him a name ("Speaker-to-Animals" being a description rather than a name), and therefore signs on too, as the expedition's security chief.
Finally, Teela Brown is a young human female whose role in the mission is not immediately clear. But Puppeteers do not do anything without a very good reason, and her significance is revealed as the plot unfolds. She is the result of a secret Puppeteer experiment in selective breeding for luck among humans, which generally helps her and her descendants. The Puppeteers reckon her luck will increase the probability of a successful mission, however it soon turns out that Teela's personal luck and the luck of the expedition seldom go hand in hand.
As they approach their target, The Ringworld turns out to be an awesome sight: a huge, circular strip of land, teeming with life and with entire oceans bigger than Earth. Between the Ringworld and its star, a series of squares (dubbed shadow squares by the expedition) are suspended in another ring, orbiting the sun faster than the Ringworld itself, thus providing the artificial world below with a day/night cycle. However, when their ship is hit by a powerful, automated meteor defense system and then strikes one of the near-invisible shadow-square wires, the expedition crash-land on the Ringworld with their vessel severly damaged. They now have to set out to find a way to get back into space, as well as fulfilling their original mission. They cross vast distances, witness strangely evolved ecosystems originating from many different planets, including Earth, 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.
In addition to the two aliens, Niven includes a number of concepts from his other Known Space stories:
* The Puppeteer's General Products hulls, which are impervious to any known force except visible light and gravity, and cannot be destroyed by anything except antimatter.
* The Slaver stasis field, which causes time in the enclosed volume to stand still; since time has for all intents and purposes ceased for an object in stasis, no harm can come to anything in its field.
* The idea that luck is a genetic trait that can be favored by selective breeding.
* The tasp, a device that induces a state of extreme pleasure in the pleasure center of the brain at the push of a button; it is used as a non-harmful method of debilitating its target and is extremely addictive. If the subject cannot, for whatever reason, get access to the device, intense depression can result, often to the point of madness or suicide.
* Boosterspice, a drug that extends human life to near immortality.
* Impact armor, a flexible form of clothing that hardens instantly into a rigid form stronger than steel when rapidly deformed, similar to certain types of bulletproof vests.
* Hyperdrives allow for faster-than-light travel, but at a rate slow enough (1 light year per 3 days, ~125c) to keep the galaxy vast and unknown; the new Quantum II Hyperdrive, developed by the Puppeteers but not yet released to humans, can cross a light year in just 1.25 minutes (~425,000c).
* Near instant point-to-point teleportation is possible with transfer booths (on Earth) and stepping disks (on the Puppeteer homeworld); on Earth, people's sense of place and global position has been lost due to instantaneous travel; cities and cultures have blended together.
* A theme well-covered in the novel is that of cultures suffering technological breakdowns who then proceed to revert to belief-systems along religious lines. Most Ringworld societies have forgotten they live on an artificial structure, and now attribute the phenomena of their world to divine power.
Ringworld parameters Radius 9.5×107 miles (~1.5×108 km) (~1 AU)
Circumference 6×109 miles (~9.7×108 km)
Width 997,000 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 "Ringworld" is an artificial ring about one million miles wide and approximately the diameter of Earth's orbit (which makes it about 600 million miles in circumference), encircling a Sol-type star. It rotates, providing an artificial gravity that is 99.2% as strong as Earth's gravity through the action of centrifugal force. Ringworld has a habitable flat inner surface equivalent in area to approximately three million Earth-sized planets. The majority of the surface is land interspersed with shallow, freshwater seas. On opposite sides of the ring are two large deep saltwater oceans, placed in counterbalance to one another. One of the large oceans, known as the "Great Ocean", contains one-to-one maps of all of the inhabited worlds of known space. The "Other Ocean" has many maps of a single world: the Pak Homeworld. Walls 1000 miles tall along the edges retain the atmosphere. The Ringworld could be regarded as a thin, rotating 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."
Source of material
The Ringworld is described as having a mass approximately equal to the sum of all the planets in our solar system. The adventurers surmised that its construction consumed literally all the planets in that system, down to the last asteroid and/or moon, as the Ringworld star has no other bodies in orbit. In Ringworld's Children it is additionally explained that it took the reaction mass of roughly 20 Jupiter masses to spin up the ring; thus the combined mass of the planets of the original system was that much larger than our solar system's.
Scrith, usually written italicized as scrith, forms the walls and floor of the Ringworld.
Scrith is a milky-gray translucent, nearly frictionless material. The fairly thin layer of scrith that forms the floor of the Ringworld blocks the passage of 40% of the neutrinos that encounter it, equivalent to almost a light year of lead. It also absorbs nearly 100% of all other radiation and subatomic particles and rapidly dissipates heat. The tensile strength of scrith is similar to the strong nuclear force, with the Ringworld foundation only about 30m (100 ft) deep. Also, it is transparent to large magnetic fields.
Due to its enormous strength, scrith is impervious to most weapons. A body (such as a comet or asteroid) striking with enough kinetic energy may be able to deform the Ringworld floor and punch a hole. The Ringworld engineers used a device, called the cziltang brone in their language, to pass from the vacuum of their spaceports right through the scrith to the habitable surface of the Ringworld.
The physical composition of scrith is unclear, but it appears to share some of the properties of a metal (albeit in a greatly exaggerated form): for instance, the high tensile strength, the ability to conduct heat and the ability to retain an induced magnetic field. Scrith is said to have been artificially produced through the transmutation of matter.
"Ringworld", or more formally, "Niven ring", has become a generic term for such a structure, which is an example of what science fiction fans call a "Big Dumb Object", or more formally a megastructure. Other science fiction authors have devised their own variants of Niven's Ringworld, notably Iain M. Banks' Culture Orbitals, best described as miniature Ringworlds, and the ring-shaped Halo structure of the video game series of the same name.
The construction of a ringworld remains firmly in the area of speculation. If such a structure were built it could indeed provide a huge habitable inner surface, but the energy required to construct it and set it rotating is so significant (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 in a time frame acceptable to humans.
Tension on material
The tensile strength of the material required would be on the same order as the strong nuclear force, according to Niven — 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 merely gives a name to the sufficiently advanced technology that would have to be used.) In later novels the "transmutation" idea is simply discarded and the construction method of scrith left open, although one engineer is able to use nanotechnology to weave new scrith into meteor punctures.
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 is stationary — in fact, it is at an unstable equilibrium, roughly comparable to a small sphere balanced on top of a larger one.
Thus, 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. He notes in the dedication of Ringworld Engineers that at the 1971 World Science Fiction Convention MIT students crowded the hotel hallways chanting "The Ringworld is Unstable!" In this first sequel, he also tackled how to prevent all the soil from ending up in the oceans. In the fourth book in the series, 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 only the Great Oceans are described as being saline.
Imperfect shadow squares
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. This is not the perfect match for a planet however, as there is no sunrise or sunset in Ringworld, and when not covered by a shadow square, the sun is always at high noon. 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. As revealed in Ringworld Engineers, the "shadow squares" also provide a shielding to the inner surface of the Ringworld when someone in the control room uses a magnetic field embedded in the Ringworld to fire the meteor defense system.
Ringworld - Larry Niven
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