Known Space

Known Space is the fictional setting of several science fiction novels and short stories written by author Larry Niven. It has also in part been used as a shared universe in the Man-Kzin Wars spin-off anthologies sub-series.

The epithet "Known Space" is an in-universe term that refers to a relatively small part of the galaxy centered around Earth. In the future which the series depicts, ranging from a few centuries to about a millennium from now, this region has been explored by humans and a number of its worlds have been colonized. On other worlds aliens have been encountered, contact has been made with alien species such as the two-headed Pierson's Puppeteers and the aggressive felinoid Kzinti. The fictional universe is also the home of species outside Known Space as such, for instance the hominid inhabitants of a megastructure called Ringworld; the Ringworld orbits a sun outside of the spatial "region" known as Known Space, but it is a well-established artifact within the Known Space "universe". The stories span approximately one thousand years of future history, from the first human explorations of the Solar System to the colonization of dozens of nearby systems. Late in the series, this area is an irregularly shaped "bubble" about 60 light-years across.

The stories that comprise the Known Space series were originally conceived as two separate series, the Belter stories, featuring solar-system colonization and slower-than-light travel with fusion-powered and Bussard ramjet ships, and the Neutron Star/Ringworld series of stories, set much further into the future, which feature faster-than-light ships using "hyperdrive". The two timelines were implicitly joined by Niven in the story A Relic of the Empire, in which the background elements of the Slaver civilization (introduced in World of Ptavvs, from the Belter series) was used as a plot element of a story in the faster-than-light setting. Roughly 300 years separates the timeline of the last stories of the early setting (which are set roughly between 2000 and 2350), from the earliest stories in the later Neutron Star/Ringworld setting (which are set in 2651 (Neutron Star) and later). In the late 1980s, Niven opened up this gap in the known space timeline as a shared universe, and the stories of the Man-Kzin Wars volumes fill in that history, joining the two settings.

Species
In the process of exploring space, humankind encounters several intelligent alien species, including the following:


 * Kzinti: Large and very aggressive felinoid aliens with whom humans fight several brutal interstellar wars. Kzinti tactics are somewhat cat-like in nature, "scream and leap" being the primary mode of declaring a challenge. The first Man-Kzin War ended when the humans obtained the faster-than-light drive from the Outsiders, after which the Kzinti ships stood no chance against FTL-drive (Faster Than Light) warships. Throughout the rest of the wars with man, the Kzinti tended to always attack before they were ready, and subsequently lost each and every one of them. As a result of this most of their empire was lost; in the peace treaties that resulted, colonies and slave planets were ceded to man or given independence. In Ringworld it is revealed that this was in part due to clandestine meddling by the Pierson's Puppeteers. They saw in the aggressive Kzinti a major threat, and orchestrated the events that led to the human FTL armada, ensuring the human victory of the first war. Each of these Kzinti defeats eliminated the most aggressive individuals from the Kzinti gene pool and thus made the Kzinti more "manageable" from a Puppeteer point of view. By the time Ringworld takes place, Kzinti are able to deal with other races diplomatically, rather than by attacking and enslaving them. Female Kzinti are not sapient, although among the archaic Kzinti found on the Ringworld some are. The protagonist Louis Wu thinks this indicates the Kzinti in Known Space have bred intelligence out of their females.


 * Niven himself wrote little about the Man-Kzin Wars, although many of his stories refer to them having taken place in the past. The Man-Kzin Wars short-story collections were primarily written by other authors. The Kzinti "crossed-over" in to the Star Trek universe in the animated episode "The Slaver Weapon", which was written by Larry Niven and is adapted from Niven's own short story "The Soft Weapon".


 * Kdatlyno: A slave species of the Kzinti until humans free them though some are still legal Kzinti slaves. Kdatlyno are huge, 10 ft bipeds with long arms. They have a thick brown hide, curved claws at knees and elbows, and retractable claws on the knuckles of their hands. Their heads are eyeless and noseless, with a gash of a mouth. Above that is a goggle-shaped tympanum (eardrum), which allows them to "see" by way of sonar. Kdatlyno create 'touch sculptures' as an art form they invented. Other species need to touch this art, rather than look at it, to appreciate it properly.


 * Whrloo: Meter-tall insectoids with long eyestalks, their homeworld has low gravity with a thick, high density atmosphere. They never saw the stars until they were enslaved by the Kzinti.


 * Pierin: A slave species of the Kzinti. At the time of their conquest, they occupied several planets near p Eridani. No description is given, but the Ringworld RPG suggests they resemble horned birds and that their homeworld has low gravity. Presumably freed by humans, but this is not attested.


 * Jotoki: Sentient starfish-shaped beings formed by the joining of the lobes of five non-sentient eel-like life forms into a single brain. Former rulers of an interstellar empire, they used Kzinti as bodyguards and mercenaries, but the Kzinti took over the Jotoki empire and built their own upon it, making the Jotoki slaves and food animals. Though superficially similar to the Gw'oth, they are unrelated.


 * Chunquen: A slave species of the Kzinti, remarkable to their captors for the sentience of both sexes. ("They fought constantly.") Their homeworld is watery; they resisted the Kzinti invasion with missiles fired from submarine ships. Apparently exterminated before the Kzinti first encountered humans.


 * Pierson's Puppeteers: A technologically advanced race of three-legged, twin-necked herbivores descended from herd animals, and noted for their so-called cowardice. Their commercial empire directly and indirectly controls events throughout Known Space and beyond, and Puppeteer plots are behind many of the larger events in Known Space. The name "Puppeteer" is purportedly derived from the twin "heads" (not enclosing brains) which perform as both mouths and hands, which strongly resemble sock puppets. The Puppeteer voice range is far greater than the human one, but for speaking to humans they adopt the tone of a very seductive female. It is also suggested that the "Puppeteer" name may derive from their social tendency to be very manipulative. The species were depicted in Barlowe's Guide to Extraterrestrials


 * Outsiders: fragile aliens shaped like cats o' nine tails that, according to Ringworld, probably evolved on a cold, low gravity world resembling Nereid. They mostly live on big ships, crossing the interstellar space at sublight velocities (according to A Gift From Earth, they find hyperspace vulgar), trading in information and technology. It was the Outsiders that sold humans the FTL drive, on a stop to We Made It. The Outsider ships' paths between the stars are determined by the starseeds, which they for some unknown reason seem to follow. The starseeds are gigantic, non-sentient space-dwelling animals that travel from the galactic core to the rim by their solar sails. At the rim they lay their eggs, then travel the 50,000 light-years back to the core.


 * Pak: Interstellar ancestors of humanity whose life-cycle mimics the stages of human aging. A Pak who reaches the age of 30 to 45 years may eat the Tree-of-Life to transform into a "Protector" of his descendants. In the novel Protector, Protectors are described as xenophobic, violent, hyper-intelligent and driven only by the fierce instinct to protect their descendants. This powerful instinct drove them to commit genocide on several planets where they tried to establish colonies, since every other sentient species was considered a potential threat to their offspring. It also led to relentless internecine wars whenever two familial lines wound up with goals in conflict. When the Protectors reappear in The Ringworld Engineers and its sequels, it is strongly indicated that they constructed the Ringworld.


 * Thrintun: An ancient species that ruled a large empire, including the region of Known Space, through telepathic mind control about 1.5 billion years ago. A technology created by one of their slave races was the stasis field, which makes its contents impervious to harm and provides indefinite suspended animation, which has figured in several Known Space stories. Thrintun were small (approximately 1.25 meters tall), highly telepathic but not particularly intelligent (with their mind control, they did not need to be), reptilian, with green scaly skin, pointed teeth, and a single eye. The species were depicted in Barlowe's Guide to Extraterrestrials


 * Grogs: Sessile sentient creatures, shaped like furry cones. They are eyeless, earless, and have a prehensile tongue. They can also control animals telepathically. The Grogs are thought by some to be the descendants of the Thrintun species, after 1.5 billion years of atrophy.


 * Gw'oth: Starfish-shaped beings Inhabiting the moon of a gas giant. They have the ability to plan ahead in great detail.  They lived in oceans under the ice of their moon and did not have fire, or electricity until after they cut through the ice and entered vacuum in basic leather suits.  Only then did they learn to make fire.  Within two generations they went from fire to nuclear fission.  The Gw'oth continue to advance rapidly without need for trial and error learning. They know nothing of other life forms in the universe but are being secretly observed by Pierson's Puppeteers and their captive humans.  Though superficially similar to the Jotoki, they are unrelated.
 * Tnuctipun: An apparently extinct ancient race of small carnivores contemporaneous with and enslaved by the Thrintun. They were known for their technological prowess, especially in genetic engineering. They secretly planned and executed the revolution to overthrow their Thrintun masters using many of their creations. When it appeared that the revolt would succeed, the Thrintun elders built and used a psychic amplifier that forced every sentient being in the galaxy to commit suicide, the signal repeating for centuries. The Thrint that survived the revolt died out when all their slave races were dead.


 * Bandersnatchi: Colossal slug-like creatures, originally created by the Tnuctipun to be grown as a food source by the Thrintun. Believed by the Thrintun to be unintelligent, the Bandersnatchi were engineered by the Tnuctipun to be highly intelligent spies for their war on the Thrintun. At one time found on every Thrint estate throughout the Thrintun empire, the only known survivors in Known Space are on the planet Jinx, though they are later found on the Ringworld and on a forested planet called Beanstalk (in the Man-Kzin Wars story "Hey Diddle Diddle"). The Bandersnatchi were the only intelligent species which were immune to the Thrint mental power.


 * Trinocs: Named for their three eyes; they also have three fingers, and a triangular mouth. They are described as 5 ft bipedal humanoids, with long legs, short torsos, and improbably flexible neck vertebrae. An unconfirmed source states that they breathe a "primordial reducing atmosphere" mainly composed of methane and ammonia, and are culturally paranoid, at least by human standards. First encountered by Louis Wu in the short story There is a Tide.


 * Martians: Primitive but intelligent humanoids who lived beneath the sands. Martians burst into flames when brought in contact with water. Martians killed many of the early human explorers on Mars, principally because they concealed their existence, and they weren't suspected. In the novel Protector, the Martians were wiped out when Jack Brennan caused an ice asteroid to crash into the surface of Mars, raising the average humidity content of the atmosphere. Some Martians still exist on the "Map of Mars" on the Ringworld.


 * Morlocks: Semi-sentient humanoid cave dwellers on Wunderland. They, like humans, descended from a failed attempt by Pak Protectors to colonize Sol and nearby star systems . Named by humans for the creatures in H.G. Wells' The Time Machine.

Also figuring in some stories are dolphins and other intelligent cetaceans, and various offshoots of Homo sapiens including the associate lineage of the hominids of the Ringworld. Most life in Known Space shares similar biochemistries, since they evolved from the Thrintun practice of seeding barren worlds with food yeast which they used to feed their slaves. Over a billion years, the Thrintun food yeast evolved into the different life forms in Known Space.

Locations
One aspect of the Known Space universe is that most of the early human colonies are on planets suboptimal for Homo sapiens. During the first phase of human interstellar colonization (i.e., before humanity acquired FTL), simple robotic probes were sent to nearby stars to assess their planets for habitation. The programming of these probes was flawed: they sent back a "good for colonization" message if they found a habitable point, rather than a habitable planet. Sleeper ships containing human colonists were sent to the indicated star systems. Too often, those colonists had to make the best of a bad situation.


 * Earth, the human homeworld, is oppressive to an extent that would be unbelievable to most contemporary humans. The entire world is under the rule of the United Nations, which wields its power by means of a global police force. For centuries, due to the perfection of organ transplant technology, all state executions were done in hospitals to provide organ transplants, and to maximize their availability, nearly all crimes carried the death penalty, including such offenses as multiple traffic tickets or tax evasion. This period ended when Jack Brennan, who had consumed the Tree-of-Life root and become a human version of the Pak Protector, used his superior intelligence to engineer social change in medical technology and social attitudes that eventually reduced the use of organ banks to reasonable levels. Part of Brennan's manipulation was the development of a science known as "psychistry". Psychistry was used to "correct" all forms of "mental aberration" - the populace is incredibly docile. To combat overpopulation (one estimate is 18 billion people), a license is required to procreate, only available after exhaustive testing has determined that a prospect is free of "abnormalities"; failure to acquire one before procreating is a capital crime. This policy, in addition to the existence of the transfer booth and a one-world language and economy, has led to the populace eventually becoming fairly genetically homogeneous. To prevent the development of new WMDs, all scientific research is regulated by the government and all potentially dangerous technology is suppressed; there have been very few real breakthroughs in science since the twentieth century. A common title for people born on Earth is "Flatlander"; they are considered naïve and a bit helpless by the rest of the galaxy, having been born and raised in the only environment in Known Space which humans are well-adapted to.


 * The Moon is a separate entity, but is under the control of the same government as Earth. It, however, has its own distinct culture. Humans native to the Moon are called "Lunies", and tend toward tall, lean body types regularly reaching eight feet in height. They are frequently referred to as looking much like Tolkien's Elves due to their physiques and alien allure.


 * Mars, fourth planet in our solar system and the first planetary colony in Known Space. Native "Martians" were exterminated by the Brennan Monster. No one goes there, as resources are easier to mine in the Belt and Jovian moons. Earth ultimately colonized Mars specifically to study the descent landing pod used by Phssthpok the Pak in 2124 AD and was still in existence in 2183 when the Martians were exterminated by Brennan.  The colony expanded greatly during the first Man Kzin war 2367-2433.


 * The Sol Belt possesses an abundance of valuable ores, which are easily accessible due to the low to negligible gravity of the rocks containing them. Originally a harsh frontier under U.N. control, the Belt declared independence after creating Confinement Asteroid, a habitat with spin gravity that permitted safe gestation of children, and Farmer's Asteroid, the Belt's primary food source. Almost immediately a lively competition began between the fiercely independent "Belters" and the technology police of the U.N. Several years of tension and economic conflicts followed, but soon settled into a relatively peaceful trade relationship as the Belt has so many resources that the UN and the Earth needs.


 * Down is the home world of the Grogs and a former Kzinti colony. It orbits a K-type star, significantly redder and cooler than Sol. Grogs, though friendly, are feared by humanity, due to their telepathic ability to control the minds of animals (and possibly sentient species as well). Because of this fear, humans have placed a Bussard ramjet field generator in close orbit around Down's sun, thus enabling them to destroy the Grog population should they ever take hostile action against any sentient species.




 * Jinx, orbiting Sirius, is a massive moon of a gas giant, stretched by tidal forces into an egg shape, with surface gravity at the habitable areas near the limits of human extended tolerance. The poles lie in vacuum, the equatorial regions are Venus-like (and inhabited only by the Bandersnatchi); the zones between have atmosphere breathable by humans. Jinx's poles become a major in vacuo manufacturing area. Jinxian humans are short and squat, the strongest bipeds in Known Space. But they tend to die early, from heart and circulatory problems. There is a tourist industry which provides substantial useful interplanetary trade credits for the Bandersnatchi in which the Bandersnatchi allow themselves to be hunted by humans under strict protocols.


 * Wunderland is a planet circling Alpha Centauri, and was the earliest extra-solar colony in Known Space's human history. It has a surface gravity of 60% that of Earth's and is hospitable to human life. Wunderland was invaded and its population enslaved by the Kzinti during the first Man-Kzin War. It was freed near the end of the First War by the human Hyperdrive Armada from We Made It. The system has an asteroid belt in the shape of a crescent, which gives it its name—the Serpent Swarm. The capital asteroid, Tiamat, houses one of the largest Kzin populations in Known Space.


 * We Made It, orbiting Procyon, got its name because the first colony ship crash-landed. Gravity is about three-fifths Earth's. The planet's axis is pointed along the plane of the ecliptic (like Uranus), creating ferocious winds of as much as 1,500 mph during half of the planet's year, forcing the people to live underground. Natives are known as "Crashlanders", and tend to be very tall albinos. Their capital, which was the site of their colony ship's landing, is called Crashlanding City. We Made It also has one ocean.


 * Plateau in the Tau Ceti system is Venus-like, with a plateau (called Mount Lookitthat), half the size of California, rising high enough out of the dense atmosphere to be habitable. Inhabitants ("Mountaineers") are divided into two rigid hereditary castes, the "crew" and the "colonists", depending on whether their ancestors piloted the colonizing vessel. The crew were the upper caste, and held power through their monopoly on organ transplantation and control of the police. The original colonists signed the "Covenant of Planetfall", agreeing that this outcome was just recompense for the labors of the crew during the voyage; that they signed at gunpoint as they were awakened from hibernation was kept secret from later generations, and also that those who refused, died. This repressive system was overthrown in A Gift From Earth, and the former inequality and caste system appears to have disappeared by the time The Ethics of Madness takes place.


 * Home was one of Earth's most distant colonies, orbiting the star Epsilon Indi. The planet was so named by the colonists, due to its remarkable similarity to Earth. Its day is nearly 24 hours long, and its surface gravity is 1.08g. Oceans, mean global temperature, seasons, and moon are also similar. According to Protector, the original colonists had planned to call their world "Flatland" as a sort of joke, but once settled on Home they had changed their minds - "a belated attack of patriotism", Elroy Truesdale of Protector muses. The entire population of Home was destroyed as a consequence of Brennan's and Truesdale's war with the Pak - Brennan turned the entire population into human Protectors to create an army to fight the Pak invaders. Home was resettled quickly though, since another ramjet with colonists was already on its way when the colony failed . In Procrustes and other later stories, Home is once again presented as a vibrant colony.


 * Canyon was once an uninhabitable Mars-like world known as Warhead. It was used as a military outpost by the Kzinti, until the planet was hit by a weapon called the "Wunderland Treatymaker" during the Third War. The attack tore a long, narrow, kilometers-deep crater into the crust approximately the size of the Baja Peninsula. The air and moisture in the thin atmosphere gathered at the bottom of this artificial canyon, creating a breathable environment, complete with a sea at the bottom. The planet was then renamed for the crater, and settled by humans in a huge city running up the crater wall. Archaic (hyper-aggressive and intractable) Kzinti were entombed in stasis field shells during the attack and are still beneath the lava, and someday, somebody will have to deal with them. The attack by the Wunderland Treatymaker is detailed as a part of Destiny's Forge, by Paul Chafe, a part of the Man-Kzin Wars shared universe.


 * Gummidgy is a jungle world popular with hunters. It is home to the Gummidgy Orchid-Thing, a sessile carnivore which hangs from trees and is a popular trophy for the wealthy. It orbits a blue giant star and due to high levels of ultraviolet light, most humans (except Jinxians) require melanin-boosting medication to venture outdoors.


 * Fafnir is a former Kzin colony covered almost entirely in water. It has one continent, called Shasht. It was captured by humans during the Man-Kzin Wars.


 * Margrave is a late addition to the family of Human colonies. In the Ringworld era it is still a frontier world, and is home to enormous birds the inhabitants have dubbed "rocs".


 * Silvereyes is, at the time of Ringworld, the furthest Human world from Earth (60 days at Quantum-I hyperdrive speeds). In Niven's obscure story The Color of Sunfire it has entire continents covered with Slaver sunflowers (bred as defense for Thrint manors, they focus sunlight using silver leaves as parabolic reflectors), giving it an appearance from orbit of having "silver eyes". The Man-Kzin Wars books, conversely, have it entirely covered by a world ocean, with groves of sunflowers growing up from the bottom of the ocean.


 * The Fleet of Worlds is the five planets that are home to the Puppeteers (see above), presently being moved in formation at sub-light speeds out of the galaxy to avoid destruction as the wave of radiation from an explosion of the galactic core sweeps towards the outer reaches of the galaxy. They orbit about each other in a Klemperer rosette.


 * Hearth is the homeworld of the Pierson's Puppeteers with a population of around one trillion and is covered by arcologies, most over one mile tall. Its industries and population generate so much waste heat it no longer requires a star for warmth (the four other "farmworlds" use artificial orbital lights to grow food).


 * Kobold was a tiny artificial world created in the outer Sol System by Jack Brennan, a human Protector, composed of a small sphere in the center ringed by a larger torus. Gravity generators facilitated movement between the two sections and were used in games and art. Brennan destroyed Kobold just prior to leaving for his war with the Pak Protectors.


 * The Ringworld is an artificial world structure with three million times the surface area of Earth, built in the shape of a giant ring orbiting its sun, a million miles across and with a diameter of 186 million miles. It was built by the Pak, who either abandoned it, or more likely died out much like the Earth Pak did, due to a lack of a key yamlike root which produces the conversion to Protector-stage Pak (which required a very specifically targeted soil chemistry to grow). It is inhabited by a number of different evolved hominid species, and includes representative samples of Bandersnatchi, Martians and Kzinti, and possibly other alien races that existed at the time of its construction.


 * Sheathclaws is a planet colonized by humans aboard Angel's Pencil and descendants of a rogue Kzinti telepath. It orbits an as-yet-unspecified star 98 light-years from Earth, and kept its existence secret for several centuries.


 * Kzin, translates as "Home-of-the-Kzinti" or "Kzinhome" in the Hero's Tongue. It orbits 61 Ursae Majoris and has higher gravity than Earth and more oxygen in the atmosphere. It has two moons, known as the Hunter's Moon and the Traveler's Moon.

Technology
The series features a number of "superscience" inventions which figure as plot devices. Stories earlier in the timeline feature technology such as Bussard ramjets, Drouds (wires capable of directly stimulating the pleasure centers of the brain) and explore how organ transplantation technology enables the new crime of organlegging (as well as the general sociological effects of widespread transplant technology), while later stories feature hyperdrive, invulnerable starship hulls, stasis fields, molecular monofilaments, transfer booths (teleporters used only on planetary surfaces), the lifespan-extending drug boosterspice, and the tasp which is an extension of the wirehead development which works without direct contact.

The impact of inventions and technology on society is a recurring, if not central theme in Niven's work. For example, addiction to electric brain stimulation resulting in "wireheads", or the secondary and tertiary effects of an invention such as teleportation on social behavior, problems, and mores.

The milieu can be viewed as representing the last gasp of Campbell-era science fiction, as the iconoclastic, counterculture influences of "new wave" science fiction of the sixties play no part in most of the stories. However, there are notable exceptions in the Gil the ARM stories; and Jigsaw Man first appeared in Harlan Ellison's landmark "new wave" anthology, Dangerous Visions.

Organ Transplantation
On Earth in the mid 21st century it became possible to transplant any organ from any person to another, with the exception of brain and central nervous system tissue. Individuals were categorized according to their so-called "rejection spectrum" which allowed doctors to counter any immune system responses to the new organs, allowing transplants to "take" for life. It also enabled the crime of "organlegging" which lasted well into the 24th century.

Hyperdrive
Faster Than Light (FTL) propulsion, or hyperdrive, was obtained from the Outsiders at the end of the First Man-Kzin War. In addition to winning the war for humanity, it allowed the re-integration of all the human colonies, which were previously separated by distance. Standard hyperdrive covers a distance of one light-year every three days (121.75 x c). A more advanced Quantum II Hyperdrive introduced later is able to cover the same distance in one and a quarter minutes (420,768 x c).

In Niven's first novel, World of Ptavvs, the hyperdrive used by the Thrint required that a ship be going faster than 93% of the speed of light. However, this is the only time that Hyperdrive is described this way.

In the vast majority of Known Space material, Hyperdrive requires that a ship be outside a solar system's gravity well to use. Ships which activate hyperdrive close to the sun are likely to disappear without a trace. This effect is regarded as a limitation based on the laws of physics. In Niven's novel Ringworld's Children the Ringworld itself is converted into a gigantic Quantum II hyperdrive and launched into hyperspace while within its sun's gravity well. Ringworld's Children reveals that there is life in hyperspace around gravity wells and that hyperspace predators eat spaceships which appear in hyperspace close to large masses, thus explaining why a structure as large as the Ringworld can safely engage the hyperdrive.

Stasis Fields
A Slaver stasis field creates a bubble of space/time that runs separate from the rest of the universe. Time slows effectively to a stop for an object in stasis, at a ratio of some billions of years outside to a second inside. An object in stasis is invulnerable to anything occurring outside the field, as well as being preserved indefinitely. A stasis field may be recognized by its perfectly reflecting surface, so perfect in fact that it reflects 100% of all radiation and particles, including neutrinos.

Invulnerable Hulls
The Puppeteer firm, General Products, produces an invulnerable starship hull, known simply as a General Products Hull. The hulls are impervious to any type of matter or energy, with the exception of antimatter (which destroys the hull), gravitation and visible light (which pass through the hull). While invulnerable themselves, this is no guarantee that the contents are likewise protected. For example, though a high speed impact with the surface of a planet or star may cause no harm to the hull, the occupants will be crushed if they are not protected by additional measures such as a stasis field or a gravity compensating field.

In Fleet of Worlds, the characters tour a General Products factory and receive clues that allow them to destroy a General Products hull from the inside using only a high-powered interstellar communications laser. In Juggler of Worlds, the Puppeteers, attempting to surmise how this was done without antimatter, identify another technique which can be used to destroy the otherwise invulnerable hulls, one which does suggest some potential defense options.

Boosterspice
Boosterspice is a compound that increases the longevity and reverses aging of human beings. With the use of boosterspice, humans can easily live into hundreds of years and, theoretically, it can extend life indefinitely.

Developed by the Institute of Knowledge on Jinx, it is said to be made from genetically engineered ragweed (although early stories have it ingested in the form of edible seeds). In Ringworld's Children, it is suggested boosterspice may actually be adapted from Tree-of-Life, without the symbiotic virus that enabled hominids to metamorphose from Pak Breeder stage to Pak Protector stage (mutated Pak breeders were the ancestors of both Homo sapiens and the hominids of the Ringworld in the Known Space universe).

On the Ringworld, there is an analogous (and apparently more potent) compound developed from Tree-of-Life, but they are mutually incompatible; in The Ringworld Engineers, Louis Wu learns that the character Halrloprillalar died when in ARM custody after leaving the Ringworld, as a result of having taken boosterspice and previously having used the Ringworld equivalent. Boosterspice only works on Homo sapiens, whereas the Tree-of-Life compound will work on any hominid descended from the Pak.

Stepping disks
Stepping Disks are a fictional teleportation technology. They were invented by the Pierson's Puppeteers, and their existence is not generally known to other races until the events of The Ringworld Engineers.

The stepping disks are an outgrowth and improvement of the transfer booth technology used by humans and other Known Space races. Unlike the booths, the disks do not require an enclosed chamber, and somehow can differentiate between solid masses and air, for example. They also have a far greater range than transfer booths, extending several Astronomical Units.

Several limitations to stepping disks are mentioned in the Ringworld novels. If there is a difference in velocity between two disks, any matter transferred between them must be accelerated by the disk accordingly. If there is not enough energy to do so, the transfer cannot take place. This becomes a problem with disks that are a significant distance apart on the Ringworld surface, as they will have different velocities: same speed, different direction.

Transfer Booths
Transfer Booths are an inexpensive form of teleportation. They are similar in appearance to an old style telephone booth: one enters, "dials" one's desired destination, and is immediately deposited in a corresponding booth at the destination. They are inexpensive: a trip anywhere on Earth costs only a "tenth-star" (presumably equivalent to a dime). Introduced by one of Gregory Pelton's ancestors, apparently bought from and based on Puppeteer technology.

In-Universe Terms

 * Autodoc - Automated facility capable of various levels of medical intervention. Models range from small "desktop" devices that can perform diagnostic procedures, administer medicine, and perform manicures; to highly sophisticated "coffin" style units that can perform major surgery and even rebuild a person from scratch using the patient's DNA (and sufficient raw material).


 * Belter Crest - The hairstyle worn by most Belters. The sides of the head are shaved, leaving a narrow strip of hair down the center 1-2 inches wide. Also known as a "Strip Cut".


 * Blind Spot - A visual and psychological effect of faster than light travel. Hyperspace produces no visual input to the brain at all. A transparent window of a ship traveling in hyperdrive will behave as the blind spot of one's eye (hence the name). The brain will attempt to fill this gap with surrounding detail, which can cause intense disorientation to an observer, and even insanity if the area of exposure is great enough.


 * Bubble World - An artificial world created by melting a large iron-rich asteroid and "inflating" it with water placed in a central borehole. The asteroid is melted from the outside in, and the water flashes into steam as the rock melts around it. The world is spun for gravity and the inner surface is terraformed. Normally found in asteroid belt colonies, where they provide farmland and gravity for women to safely carry their unborn children to term.


 * Corpsicle - A person in cryonic suspension (portmanteau of "corpse" and "popsicle"). Often used disparagingly.


 * Droud - A device for direct electrical stimulation of the brain's pleasure center, plugged directly into a socket that is surgically attached to the skull. The user of a droud, known as a "wirehead", suffers from "current addiction". The operation to attach the droud's socket is performed by a specialized surgeon known as an "ecstasy peddler". If ever "taken off" the device it can lead to severe depression and possibly suicide.


 * Far Look - A trance state, similar to highway hypnosis, sometimes experienced by Belters as a result of staring into the infinity of space for extended periods of time.


 * Fertility Board - Agency of the U.N. which grants or denies parenthood licenses to individuals based on one's genetic tendencies or talents.


 * Free Park - A park where there are no rules, save that no one may harm another. The sole rule is enforced by floating monitor/stunners known as "copseyes".


 * Fusion Tube - A cylindrical shield designed to confine a plasma undergoing thermonuclear fusion. It prevents the plasma heat from damaging the external components of the reactor (and also prevents the cold components from contacting the plasma, which would cause it to fail). The shield can be modulated to allow desired radiation (such as visible light) to pass through it. This is useful for when the fusion reactor is used as both a power source and a light source, such as in the Belt bubbleworlds: Confinement and Farmer's Asteroid.


 * Grippy - All purpose hand tool used chiefly in space.


 * Gravity Polarizer - A device which provides levitation and propulsion by creating a localized distortion of space-time curvature.


 * Handicapped - When capitalized, refers to species with intelligence but no hands (or other appendages) with which to manipulate their environment. Examples are Earth's cetaceans, the Bandersnatchi of Jinx, and the Grogs on Down.


 * Interworld - Constructed auxiliary language used by the people of Known Space. Primarily used by humans, it is also spoken by Puppeteers and Kzinti.


 * Legal Entity - Any member of a sentient/sapient species, capable of independent thought and entitled to full civil rights.


 * Mercy Bullets - A form of non-lethal ammunition. Thin slivers of anesthetic material are fired from a specialized gun or rifle. They are designed to easily pierce the skin and dissolve quickly in the bloodstream, causing immediate unconsciousness. Used by ARM agents and organleggers alike.


 * Organlegger - A dealer in black market organ transplants (portmanteau of "organ" and "bootlegger").


 * Ramrobot - Unmanned fusion-driven spacecraft equipped with a Bussard ramjet, which provides a nearly limitless supply of fuel. Used as scouts during the early stages of interstellar colonization by Earth.


 * Singleship - A small spacecraft occupied and flown by only one person. It is a term short for "single"-occupant space "ship". The singleships are commonly used by Belters for mining and transportation. During the Man-Kzin Wars they were also used as warships, since the fusion jet (so the colloquial name a "Torchship") which propels the vessel could be used like a miles-long flamethrower.


 * Slowboat - Human colony ship used prior to the invention of hyperdrive. Due to strong magnetic fields, humans were unable to ride the early ramscoop-powered craft. Slowboats followed behind ramrobots and typically carried sufficient fuel only for a one-way voyage.


 * Stasis Box - Refers to containers holding preserved relics of a billion year-old war which killed every sentient race living in the galaxy at the time. Scattered across the galaxy, their contents are beyond value (and often very dangerous to the unwary).


 * Struldbrug's Club - organization catering to older humans and their needs. Named for Johnathan Swift's immortal (but not ageless) humans. Given the benefit of decades to centuries of life experience, Struldbrugs were often highly influential in society. During the 21st and 22nd century, as human longevity began to increase significantly, the minimum age for admission rose by one year for every two years that passed.


 * Tanj - Expletive. Acronym for "There Ain't No Justice".


 * Tasp - A device that can stimulate the pleasure center of the brain via electric induction at varying levels, even at a distance. Such a jolt of pleasure can be as totally disabling as a similar jolt of pain could be. More so, repeated use of the tasp at a low level can become addictive, allowing even greater control of the subject. Less malignantly, their use had become commonplace in parks on Earth, to give an unexpected shock to random passers-by, before their use was banned by the ARM. The act of randomly zapping people with a tasp was called "making their day".


 * Thruster - Device which converts one form of energy (presumably electrical) into uniform acceleration in one direction. Safer than conventional drives, it produces no dangerous reaction "back blast" as that of fusion or chemical rockets. It is a reactionless drive.


 * Variable Sword - An ultra-thin wire of molecular monofilament, made rigid and protected by a stasis field, forming a nearly invisible (and extremely sharp) blade. The wire can be extended to varying lengths (hence the name) and has a glowing red ball to mark the end of the blade.

ARM
The ARM are the police force of the United Nations. ARM originated as an acronym for "Amalgamation of Regional Militia", though this is not a term in current usage by the time of the Known Space novels. An agent of the ARM, Gil Hamilton, is the protagonist of Niven's sci-fi detective stories, a series-within-a-series gathered in the collection Flatlander (Confusingly, "Flatlander" is also the name of an unrelated Known Space story.)

Their basic function is to enforce mandatory birth control on overcrowded Earth, and restrict research which might lead to dangerous weapons. In short, the ARM hunts down women who have illegal pregnancies and suppresses all new technologies. They also hunt organleggers, especially in the era of the "organ bank problem". Among the many technologies they control and outlaw are all trained forms of armed and unarmed combat. By the 25th century, ARM agents were kept in an artificially induced state of paranoid schizophrenia to enhance their usefulness as law enforcement officials, which led to them sometimes being referred to as "Schizes". Agents with natural tendencies toward paranoia were medicated into docility during their off duty hours, through the aforementioned science of psychistry (see Madness Has Its Place and Juggler of Worlds).

Their jurisdiction is limited to the Earth-Moon system; other human colonies have their own militia. Nevertheless, in many Known Space stories, ARM agents operate or exert influence in other human star systems through the "Bureau of Alien Affairs" (see In the Hall of the Mountain King, Procrustes, The Borderland of Sol, and "Neutron Star"). These interventions begin following the Man-Kzin Wars and the introduction of hyperdrive, presumably as part of a general re-integration of human societies.

Stories in Known Space
Unlike many fictional universes, the component tales of Known Space were largely released as short stories or serials in various science fiction anthology magazines. These stories were generally subsequently released in one or more collection volumes. To add some further confusion, some of the shorter novels published in magazines were later expanded to, or incorporated in, book-length novels. Due to the large number of stories, it is particularly difficult for a completionist fan to read every story in the series. There are also two or three short stories which share common themes and some background elements with Known Space stories, but which are not considered a part of the Known Space universe: Bordered in Black and One Face (see the collection Convergent Series), and possibly The Color of Sunfire. In the Known Space stories, Niven had created a number of technological devices (GP hull, stasis field, Ringworld material) which, combined with the "Teela Brown gene", made it very difficult to construct engaging stories beyond a certain date — the combination of factors made it tricky to produce any kind of creditable threat/problem without complex contrivances. Niven demonstrated this, to his own satisfaction, with Safe at Any Speed. After 1975, he began to write significantly fewer Known Space stories. However, Niven later invited other authors to participate in a series of shared-universe novels, with the Man-Kzin Wars as their setting.

Stories by Niven
(Note that most stories appeared in more than one collection; they may not all be listed here.)

Playground
Niven has described his fiction as "playground equipment", encouraging fans to speculate and extrapolate on the events described. Debates have been made, for example, on who built the Ringworld (Pak Protectors and the Outsiders being the traditional favorites, but see Ringworld's Children for a possibly definitive answer), and what happened to the Tnuctipun. However, Niven also states that this is not an invitation to violate his copyrights, so fans should try to avoid publishing works that are too obviously based in the Known Space universe without Niven's given permission.

Niven was also reported to have said that "Known Space should be seen as a possible future history told by people that may or may not have all their facts right."

The author also published an "outline" for a story which would "destroy" the Known Space Series (or more precisely, reveal much of the Known Space background to be an in-universe hoax), in an article entitled "Down in Flames". Although the article is written as though Niven intended to write the story, he later wrote that the article was only an elaborate joke, and he never intended to write such a novel. The article itself notes that the outline was made obsolete by the publication of Ringworld. "Down in Flames" was a result of a conversation between Norman Spinrad and Niven in 1968, but at the time of its first publication in 1977 some of the concepts were invalidated by Niven's writings between '68 and '77. (A further edited version of the outline was published in N-Space in 1990.)