Conjoiners or the Conjoined (pejoratively referred to by outsiders as spiders) are a faction based around mental augmentation and communication, and the advancement of the human mind. Early experiments by the Conjoiner matriarch Galiana and her group on Mars in the early 22nd century with the uses of technology in augmenting consciousness prompted her to begin experimenting with allowing her subject's implants to communicate — triggering the event known as the Transenlightenment, and the beginnings of the Mother Nest and of the Conjoiners. After losing a war with the remainder of humanity, the first Conjoiners later escape the Solar System with the help of Nevil Clavain and colonise other star systems. They then progress to a technological level considerably ahead of the rest of humanity, although still far behind many alien cultures in nearby space. The Conjoiners function as a single society for centuries, before the events of Redemption Ark result in them splintering into numerous factions and disappearing from the affairs of baseline humanity by the time of Absolution Gap, by which point they are engaged in the war with the Inhibitors. With the "Rise of the Greenfly", other human factions are wiped out, leaving an isolated enclave of Conjoiners as the last humans in the galaxy, along with the Ultranaut Irravel. Even they are forced to flee eventually, as the Greenflies' grip on the galaxy increases.

Conjoiners use technology to create a localised group mind. Individual identities are retained, but the group generally functions as a single unit working harmoniously toward its goals. All Conjoiners possess, at the minimum, a net of nanomachines that mimic their host's brain structure and thus augment the host's neural capabilities. Artificial enhancements such as vision overlays are not uncommon, and Conjoiners can communicate neurally through fields generated by their implants, which may or may not be amplified by background systems depending on the situation. Most Conjoiners use only neural communication with other Conjoiners and do not physically speak. Their implants also offer them a host of other abilities, such as the ability to hack into and operate a considerable amount of advanced machinery; they have little trouble overriding most software security protocols save their own, and can reprogram weapons to attack their users. They also typically modify their own bodies (often using muscle fibres based on those of chimpanzees) to make themselves physically stronger. Also, at least by the 26th century, more modern Conjoiners possessed a cranial crest. As well as being aesthetically pleasing, it allows dissipation of the huge amounts of thermal energy their super-charged brains produce.

Conjoiners are typically used to being part of a group mind, and most experience disquiet or worse if cut off from other Conjoiners. The few who are capable of operating by themselves are viewed with ambivalence by the rest of Conjoiner society. Notable individuals with this capability include Clavain, Khouri, Skade, and Remontoire. For some, particularly Clavain, it is suspected that this ability has to do with the outdated technology of his implants, which still persist from the very early days of the Conjoiners. In addition to this, Clavain, Skade and Khouri were all born outside the Conjoiners and joined them later, resulting in them being less immersed in the transenlightenment than those born into the collective. (It should be noted that virtually no Conjoiners in the novels are actually affected by leaving the collective mind and rejoining it later).

Although Conjoiners seem monolithic and even like a hive mindto outsiders, they each possess their own varied and distinct personalities and deep divisions of thought and opinion still persist amongst them. Clavain later tells other characters that each Conjoiner is in fact different and has a different mind as all humans do; normal humans simply cannot see it.

The Conjoiners were first introduced in the short story "The Great Wall of Mars", which was first published in Spectrum SF #1, in February 2000, but republished in the collection of short Novellas, Galactic North (2006). At this point, the Conjoiners lived on Mars and the Transenlightenment was relatively recent. The story includes Nevil Clavain, initially an outsider, meeting Galiana and Remontoire, and then joining the Conjoiners. The Conjoiners are barely mentioned in the novels Revelation Space (2000) and Chasm City (2001), but are the centre of the short story "Glacial", first published in Spectrum SF #5 in March 2001, again republished in Galactic North (2006), which takes place at humanity's first interstellar colony. The Conjoiners are the central focus of the next novel, Redemption Ark (2002), and feature prominently in the following novel, Absolution Gap(2003).

In the afterword of Galactic North, Alastair Reynolds comments that the Conjoiners are not an entirely new concept, and may owe some of their origin to the Human Hive-mind culture from Michael Swanwick's Vacuum Flowers.


Cache Weapons

The Cache Weapons, also known as "Hell Class" weapons, first appeared in Revelation Space but were built by the Conjoiners some time before the events in that novel begin. The weapons were built based on information believed to have been received from the future via the project Exordium. Concerns about the source of information and the power of the weapons lead the Conjoiners to destroy the knowledge necessary to build additional weapons shortly after construction was completed, and though carefully hidden, they were eventually recovered by a crew of Ultras some years before the events in Revelation Space. Only forty cache weapons were created, and though Clavain and Remontoire speculated on creating more by reverse-engineeringthe technology, this never occurs in the novels.

The weapons are possessed of intelligence at least the level of a gamma level simulation. Sizes vary, but all are approximately sixty to seventy meters long and bronze/green in appearance. The weapons are self contained (save for targeting data) and self propelled, with at least an interplanetary range. After being deployed outside the hull of their carrier vessel, their own engines move them to a safe distance while acquiring a target. In the novels it is not entirely clear the degree of independent thought that each weapon is capable of, nor is the degree of security in remote control entirely known. They seem, however, to be fundamentally able to make their own choices about whether or not to fire and whom to target, being able to override the pacification codes the Conjoiners programmed into them (Cache Weapon Seventeen, given its Gamma-level personality, was only ever convinced to fire, no other cache weapon was listed)

The power and nature of the weapons varies, and is not fully understood in all cases. The smallest of the weapons seem to have been considerably more powerful than conventional space-borne weapons, and at least one is deemed capable of destroying a planet-sized object from a distance exceeding 100 AU. It is suggested that some of the weapons can have negative effects upon stellar bodies. Their level of sophistication differs widely- the most basic cache weapons appear to be radical extensions of otherwise conventional principles, such as relativistic projectile weapons with antimatter or neutronium ammunition and gamma-ray lasers. Others, however, make use of gravity wave effects and other complex phenomena, with certain weapons even containing microscopic black holes. Once a weapon is programmed to fire, the process cannot be stopped by any method short of destroying it. Some of the weapons appear to be single use, including some deployed in the novel Absolution Gap (in several cases this is because the weapon destroys itself when firing), while others are at least theoretically capable of being reloaded, though this is never attempted.

Conjoiner Drive

Conjoiner drives are starship engines that use quantum mechanics to propel starships up to relativistic speeds, giving such ships the name "lighthuggers". It is at one point said that Conjoiner drives contain a small wormhole linked to the very deep past, through which they draw their propulsion energies from the Quark-gluon plasma created by the Big Bang. In Redemption Ark, their design is implicated as attracting the Inhibitors, and subsequently modified after a 100-year suspension of their production (referred to in Revelation Space). It should be noted that the Conjoiners did not actually invent the drive themselves, but received the instructions for it via the Exordium.

A small part of the workings of the drives is revealed in Galactic North. The drive has six manual control dials that allow the power of the drive to be varied. As the drive power is increased, so does the risk of an uncontrolled, ship destroying explosion. Lighthuggers mount a pair of Conjoiner drives, both of which are controlled by a disembodied Conjoiner brain that performs rapid calculations to control the internal drive reactions. If the turbulence within the drive exceeds the ability of the brain, the drive will explode. The drive is also designed to explode if non-Conjoiners attempt to open it for reverse engineering, or if the gap between two drives on the same ship grows too large. This occurs because the Conjoiner brain is housed within one of the engines and controls the other remotely; once the other drive passes out of the brain's control, the internal reactions quickly spiral out of control.

Cryo-arithmetic engines

Cryo-arithmetic engines are a specific class of quantum computer discovered by the Conjoiners. When certain algorithms are executed on processors of this architecture, it leads to a local violation of the Second law of thermodynamics: the computer gets colder instead of hotter. Consequently, cryo-arithmetic engines have massive industrial (as opposed to computational) ramifications for Conjoiner manufacturing; such engines abound in Conjoiner asteroid factories, where their calculations can drain away the heat of starship construction.

Cryo-arithmetic engines are also used by the Conjoiner's modern 'stealthed' lighthuggers; they cool the exterior of the ship to the temperature of ambient space, making the starships difficult for the Inhibitors (or other foes) to detect.

Like many of the technologies in the Revelation Space universe, the cryo-arithmetic engines can have potentially catastrophic consequences in the event of an accident. In Absolution Gap, Skade's ship crashes in the ocean of the planet Ararat, and the cryo-arithmetic engines malfunction. Their control systems fail, and so they get colder. Getting colder enables them to calculate faster, prompting a positive feedback loop. By the time the inhabitants of Ararat find the wreck, Skade's ship is encased in an ever-expanding iceberg.

There is currently some research that has began to take the shape of creating cryo-arithemetic engines. Link to Reference The continious increase in the speed of processors has created a need for cryo-arithmetic engines in order to maintain moore's law past a certain theoretically information processing threshold. Such heat dissipating engines maybe in fact the only way to continue to increase the speed of processors past the next 20-30 years as energy densities increase past any perceivable way to dissipate the heat generated in processors of that time classically.


Exordium is a method of communication, wherein its participants create a "tunnel" or link through spacetime to exchange knowledge across temporal loci. The Many-worlds interpretation of quantum mechanics is assumed, and allows participants to form neural links with their past, future, and alternate selves via the instigation of quantum superposition states in their neural implants. Galiana and Skade use this system to obtain and modify inertial suppression technology and take various precautionary actions to eliminate the existential threat of the Inhibitors.

One limitation of the technology appears to be the total informational capacity of the superposition states—each instance of communication makes subsequent attempts more difficult in an effect described similarly to the build-up of static interference. It is unknown whether this limitation holds only for each individual repeat participant (which seems more likely) or for the entire process independent of the participants. Also never explicitly stated is the exact effect of the process' acausal nature, though it is implied that it cannot be used to directly violate causality. Instead, each use of the Exordium creates a new timeline in which the message is received. The original timeline in which the message was sent continues as before.[1]

A similar system to the Exordium is used in Chasm City by the race known as "grubs" to achieve faster-than light communication. It does this by grouping all messages ever sent into a massive far-future archive (known as "Galactic Final Memory") and sending them back to their recipients. It uses the local gravitational background as a key, making it impossible for other recipients to read the messages and gives the device a "range" of a few thousand light years. This also means, however, that the technology cannot be used to send information to other times. It also appears affected by the interference effect which damages the Exordium.

==Lighthugger == Lighthuggers are spacecraft that travel at just below the speed of light, taking months or years to accelerate to their cruising speed. Although capable of extremely powerful bursts of acceleration, when in transit between stellar systems lighthuggers typically sustain an acceleration of 1 gwhich would enable them to reach 99% of the speed of light in about 1 earth year.

Generally 3–4 km long, they use Conjoiner drives for propulsion, and are also coated with a thick caul of ice that protects against minor impacts at relativistic velocities and acts as armour against the attacks of other ships. The great size of the lighthuggers enables them to carry vast numbers of passengers and huge amounts of cargo. At the end of Redemption Ark this is demonstrated by Ana Khouri and Triumvir Ilia Volyova as they load approximately 160,000 of the almost 200,000 on the world Resurgam onto the Nostalgia for Infinity.

Lighthuggers are also described as having a limited repair and redesign capability in the novels. They are capable of moving rooms or machinery around within their hulls, or stripping material from one point to repair another. At least some are also equipped with "manufactories", which can build a considerable range of devices, given the relevant specifications (the full extent of their capabilities is unknown as they are only ever used in the novels to produce weapons). These ships were also quite powerful, by the standards of most science-fiction. Their small, point-defenceweapons (ostensibly defensive in nature) were capable of drilling a 200 kilometre crater in a planet and disrupting weather formations in a fashion similar to a large geological event, such as an asteroid impact or volcanic eruption.

Most lighthuggers are owned or ruled by their crew of Ultranauts, who, because of their long stretches in reefersleep and constant hopping from one star system to another are mostly divorced from baseline humanity. They are characterized by extreme modifications, often in the form of replacement or mechanical limbs or even holes right through them (as seen in Chasm City).

By the end of the sequence, there exists a fleet of lighthuggers that have been upgraded or built from scratch by the Conjoined and other elements fighting the Inhibitors. These ships are far more advanced than the average lighthugger, and are equipped with stealthed drives that do not emit in any detectable spectrum, "cryo-arithmetic engines" which cool the hull to make it nearly indistinguishable — in thermal terms — from empty space, inertia suppression machinery that allows extremely fast acceleration and deceleration, and extremely heavy armaments, including hypometric weaponry.