The Warp

“The Warp is a strange and terrible place. You might as well throw a traveller into a sea of sharks and tell him to swim home as send him through the Warp unprotected. Better it is not to let common man travel through the stars. Better still, let him not know such a thing is feasible.”

—Fra Safrane, 5th Aide to Navigator De’el.


The Immaterium (also referred to as the Empyrean, the Aether, the Sea of Souls, the Realm of Chaos, Warpspace or most commonly, the Warp) is an alternate dimension of purely psychic energy that echoes and underlies the familiar four dimensions of the material universe. It is the source of all psychic powers and known instances of so-called “sorcery” or “magic” as well as the home dimension of the Chaos Gods and their myriad daemonic servants. In fact, the terms “Chaos” and “the Warp” are often used interchangeably by those aware of their existence within the Imperium of Man. Superficially, the Immaterium is Mankind’s solution to the problem of faster-than-light travel. This function as an FTL medium for interstellar travel is achieved because the Immaterium is a domain of pure psychic energy, with voidcraft navigating between its currents, as in an ocean.

The psychic energy that makes up the Immaterium is believed to be the direct result of the existence of sentience in the universe, in particular the intelligent species of the Milky Way Galaxy. Considered to be a dark reflection of the material universe, the Warp is an ocean of chaotic psychic energy, raw emotion given physical form. Stirred by strong emotion and action, the Immaterium is the true Realm of Chaos, home to the Dark Gods who comprise the Ruinous Powers and their legions of daemonic followers. The Immaterium is also rumoured by many cultures, human and xenos alike, to be the final resting place of the spirits of the dead, and therefore can be considered as the “Underworld.”

Warp Travel

A voidcraft enters the Warp by activating its Warp-Drive. As a ship leaves the material universe it enters a corresponding point in Warpspace. The ship is then carried along by the tides and currents of the Warp, like a pebble in a raging river. After travelling in this fashion for an appropriate time, the voidship uses its Warp engines to drop back into realspace. Because the material universe and the Warp move relative to one another, the voidship reappears in a new position several light years from the starting point. This process is called a Warp jump or a hop, and the process of entering or leaving the Immaterium is known as a drop, shift, or translation.

Journeys through the Warp are usually undertaken in short jumps of up to four or five light years. Longer jumps are unpredictable and dangerous. The tides of Warpspace move in complex and inconsistent patterns, and voidships attempting longer hops often end up widely off-course. Were this limitation to apply to all Warp travel, then Humanity would not have spread throughout the galaxy as it has. It is possible to make long jumps of many light years by steering a voidship in the Warp itself — sensing, responding to, and exploiting its currents and thereby directing the craft towards a corresponding point in the material universe. Only the strain of human mutants known as Navigators can pilot a craft through the Warp in this way.

Some individuals are sensitive to the movements of Warpspace. They can, for example, sometimes tell that a voidcraft is approaching even before it drops back into the material universe. Human sensitivity to the Warp is not generally well-developed. However, in a minority of people this sensitivity is far more finely tuned. These people are known as psykers, and they are able to consciously control and use the energy of the Warp to affect the material universe. Navigators possess psychic gifts of a specialised kind that allows them to use their powers to steer spacecraft in the Warp.

The Astronomican and the Warp

The Astronomican is a psychic homing signal centred upon Terra. It is powered by the continuous mental concentration of a thousand psykers. The Astronomican cannot be detected in the real universe — only in the Warp. It is by means of this signal that the Navigators can steer their voidships over long distances. The Astronomican’s signal is strongest close to Terra and the Emperor of Mankind who is its source and gets increasingly weaker further away. It extends over a spherical area with a diameter of about 50,000 light years. The Astronomican does not extend to the extreme fringes of the galaxy, and because Terra is situated in the galactic West, its signal does not reach a massive swathe of the eastern part of the galaxy at all. Nor is the extent or strength of the signal constant — it can at times be blocked by localised activity within the Warp itself. Such activity may be compared to the hurricanes or storms of a terrestrial weather system and is known as a Warp Storm. Warp Storms may be so bad, and so long-lasting, that entire star systems are isolated for hundreds of standard years at a time.

A Warp Storm not only obscures the signal of the Astronomican, it is also dangerous for spacecraft travelling nearby. No spacecraft can venture within a Warp Storm and expect to survive, although there are tales of miraculous escapes and of starships being thrown tens of thousands of light years off course. Warp Storms are not the only dangers within the Warp. There are sentient energies and other immaterial life-forms that inhabit it, creatures formed from, and part of, the shifting stuff of the Warp. Few are friendly and many are hostile. They are known to Mankind as daemons.

Time Displacement

The time differences between realspace and Warpspace are quite drastic. Not only does time pass at different rates in both kinds of space, but it also passes at very variable rates. Until a voidship finishes its jump, it is impossible for a ship’s crew to know exactly how long their journey has taken in realspace. Time passing in realspace is referred to as “real time.” Time passing on board a spacecraft is referred to as “Warp time.”

Warp Navigation

Once a spacecraft activates its Warp-Drive, it is plunged into a dimension very different from the material universe. It is convenient to imagine Warpspace as consisting of a relatively dense, almost liquid, energy, devoid of stars, light and life as it is commonly known. Once within Warpspace a voidship may move by means of its main Newtonian reaction drive (such as a standard Imperial Plasma Drive), following powerful eddies and currents in the Warp, eventually reaching a point in the Warp corresponding to a destination in realspace. The most difficult aspect of Warp travel is that it is impossible to detect the spatial movement of Warpspace once a voidship is in the Warp. The ship can only blindly carry on, its crew trusting that it is going in the right direction. The longer a ship remains in Warpspace, the greater the chances of encountering some unexpected current that can turn it unknowingly off-course.

Navigation of Warpspace can be achieved in two ways: the calculated jump and the piloted jump.

All Warp-Drives incorporate navigational mechanisms. When the voidship is in realspace, these monitor the ever-shifting movements of that part of the Warp corresponding to the voidship’s current position. It is a “window” into Warpspace. By means of observing these movements in the Warp it is possible to calculate a course, corrective manoeuvres, and approximate journey time to a proposed destination. Calculation relies on the assumption that the Warp-currents observed from realspace do not change significantly during flight. This method is known as a “calculated jump.” It is not safe to make a calculated jump of more than four light years at one go. The longer the jump, the greater the chances of a significant change in Warp current movement.

The second, and more efficient, form of Warp-navigation is the piloted jump. This method relies upon two factors: the Navigators and the psychic beacon of the Astronomican. The Astronomican is centred on Terra and is not only controlled by, but is directed by, the psychic power of the Emperor. The Astronomican is a psychic beacon that penetrates into Warpspace. A Navigator on board a voidship in the Warp is able to pick up these signals and can steer a spacecraft through Warpspace, compensating for current changes as he does so. A piloted jump can cover a far longer distance than a calculated jump. Most piloted jumps are no more than 5,000 light years at a time, but longer jumps have been made.

A typical interstellar voyage might begin with a cargo ship lying in orbit around an Imperial world. Tiny shuttlecraft busily transfer precious minerals, foodstuffs, crew, and manufactured items from the world below. The loading procedure may take solar days or weeks, as the shuttles return time and time again to the huge voidship. Once loading is complete, the colossal spacecraft slowly accelerates out of orbit under the power of its main reaction drive. The voidship heads outwards towards the rim of the solar system, carefully increasing speed by tiny increments as it does so. Although the vessel’s engines are capable of terrific acceleration, the risk of collision with inter-planetary debris is high if the voidship accelerates too quickly or too much. As the sun shrinks in the ship’s wake, the density of debris lessens and the ship’s speed reaches approximately one percent of light speed in a vacuum.

After several solar weeks of travel, the voidship arrives at its first destination. This is the “jump-point” lying around the star system like the circumference of a circle. This delineates the point at which inter-planetary debris falls below maximum Warp density. Once this invisible line has been crossed, it is safe to activate the Warp engines. A crew careless or foolhardy enough to prematurely activate Warp-Drive would be lucky to find their ship hurled thousands of light years off course. More likely, the voidship would be torn apart and destroyed, never to be heard of again.

With the safe activation of its Warp-Drive, the ship is plucked out of the real universe and enters the dimension of Warpspace. Its true interstellar journey has begun. Ships travelling in Warpspace do so by means of jumps varying in length up to 5,000 light years. Only a long journey would involve more than a single jump. Even so, almost two solar weeks pass onboard ship before the craft is ready to end its jump. Meanwhile, because of time shifts in Warpspace, over a standard year has passed in the real universe.

The ship re-enters realspace just beyond the jump-point of its destination solar system. If it is lucky, the ship will come out close to the jump-point, otherwise it may take many extra solar weeks to reach the inner planets. It is always wise to allow a safe margin when jumping towards a star. The results of reentering space within the jump-point would be the same as prematurely activating the Warp-Drive on the outward journey, and would almost certainly end in disaster. The ship is now ready for its final haul, beginning by broadcasting to its destination and establishing a new time coordinate. Time in Warpspace is so different from time in normal space that the crew has no idea whether their journey has taken a few solar months or standard years. Initially, the voidship travels at approximately one percent of light speed, decelerating gradually through the denser inner regions. Eventually, the ship reaches its destination, where swarms of tiny shuttles once more make themselves busy loading and unloading cargo and passengers in preparation for the voidship’s next journey.

Warpspace Channels

In theory it is possible to travel anywhere in the universe through Warpspace. However, the shifting tides of the Warp make it easier to travel from some systems to others, and short Warp jumps are always more accurate than longer ones. This is particularly true when moving a large fleet, which may become spread out across several light years of space over an extended journey. Long established and well-charted Warpspace channels connect star systems and entire regions of the galaxy, providing relatively predictable conduits through which the majority of Imperial shipping passes.

Warp Gates

A Tech-Priest investigating a newly discovered Warp Gate
A Warp Gate is a point in realspace which is linked to another point in realspace by a tunnel through Warpspace. The tunnel somehow avoids the normal disturbances of Warpspace, allowing a journey to be made within a fixed time and in perfect safety. The existence of Warp Gates represents something of a mystery, and much debate rages over whether they are natural or artificial. If artificial, then none can say who made them or for what purpose. Furthermore, some Warp Gates have been artificially enhanced, their entrances delineated by mechanical constructions whose exact function can only be guessed at. Other Warp Gates are mere black holes in space.

Warp Gates occur in the depths of space, at the boundaries of solar systems, within solar systems, and even on planets. The largest are easily big enough to permit the passage of spacecraft and are usually situated at the edge of a solar system or amongst its outer planets. Other gates are only large enough to permit the passage of small vehicles, or perhaps human-sized creatures. These occur mostly on planet surfaces and lead directly to other gates on the surfaces of other planets. All gates are rare, the smaller types extremely so. Planetary gates are often disguised, or respond only to electrical, psychic, or other signals, which would seem to indicate a certain amount of intended secrecy on the part of their builders.

All space-going races are prepared to utilise Warp Gates when they find them, although discovering where they lead can often be hazardous. Many gates appear to be defective, and can dump a ship randomly into Warpspace. Others can lead to places which may once have been stars or planets, but which are now no more than empty space. The possibility of emerging into a distant, hostile alien star empire also has to be considered. It may be that spacecraft vanishing into Warpspace have been transported beyond the galaxy itself. Warp Gates often become extremely important to whomever controls them, and many are of vital strategic value to the Imperium. Imperial Commanders and other interests vie for control of a Warp Gate in their sphere of influence, and these relics are often heavily defended against outside attack.

Warp Portals

A Warp portal is a point in space where the Warp and realspace interface, forming a stable entrance into, and exit from, Warpspace. It is not necessary to activate a Warp-Drive to enter the Warp in this manner, although any vessel not equipped with Warp Shields would be unlikely to survive for long within the Empyrean. It does not lead to a tunnel, and a voidcraft entering a portal is directly cast into the chance currents of Warpspace. With careful manoeuvring it may be possible to re-enter normal space using the same portal from the other side. Again, the exact nature of the portals is not understood, and no one knows whether they are mere accidents of nature and non-Euclidian geometries or have some secret purpose. Some aliens use Warp portals to travel between Warpspace and realspace, specifically the creatures known as Enslavers, who live within Warpspace itself. Like Warp Gates, portals occur in all places in the universe and may appear on a planet’s surface. Some have a definite physical constituent, whilst others are invisible or take the form of a hole in the ground or a dark cave mouth. Warp portals do have their uses, for there are recorded instances of spacecraft with damaged Warp-Drives, trapped within the Warp and doomed to destruction, suddenly locating a Warp portal enabling them to return to realspace.

The Thin Veil

The barrier between reality and the Warp is not equally strong across the galaxy. In some places, the veil is thin, allowing the influence of the Warp to leech through. Such areas might be permanent or temporary, and could be of nearly any size, the result of random chance or the intentional acts of malefic cults. Some are the result of experiments performed during the Dark Age of Technology, while others are a side effect of psychic activity or a great effusion of powerful emotion or death. In the Askellon Sector, for example, the unpredictable currents of the Pandaemonium batter the shores of reality, weakening the barrier between dimensions.

Various disturbing phenomena can manifest in areas where the veil is thin, for the Warp and its influence are never predictable or consistent. Such places are often considered haunted or ill-omened, for people might hear voices, glimpse movement out of the corners of their eyes, or experience nightmares or even waking visions. Chronos might run backwards, temperatures plummet or fluctuate, and Auspexes and scanners provide inconsistent or contradictory readings. Individuals might feel a sense of wrongness that they cannot describe, or strange and disturbing sensations, from tingling on the skin to the smell of burning flesh.


The extrasensory, seemingly magical abilities of the psychically-gifted individuals known in the Imperium of Man as psykers are powered by the energies of the Warp, and when such power is used, the daemons and creatures of the Immaterium are drawn to the psyker’s mind like moths to a flame. Those humans trained in the use of the psychic arts are able to resist such incursion to a degree, but the greatest fear of the Imperial Inquisition is the fact that an untrained human psyker of sufficient power can become the target of daemonic possession — and a gateway for the intrusion of the daemonic servants of the Ruinous Powers into the physical world.

Realm of the Dead

Many cultures of the Milky Way Galaxy, both human and xenos, believe that the Immaterium is the final resting place for the souls or spirits of the dead. Certainly there is some truth to this notion. The Eldar believe that upon their deaths, their souls travel into the Warp where they are immediately devoured by their race’s ancient enemy, the Chaos God Slaanesh. Because the Eldar’s hedonistic and intensely psychic nature was responsible for bringing Slaanesh into existence within the Empyrean following the Fall of the Eldar sometime between the 29th and 30th Millennia, it can be said that Eldar souls have a form of “psychic gradient” in which they are immediately consumed by the hunger of Slaanesh upon the death of their physical bodies if protective measures are not taken. For the Eldar of the Craftworlds, this protection takes the form of the Spirit Stone worn by every one of their number which immediately absorbs their soul’s psychic energy upon death so that it can later be deposited for safekeeping within their Craftworld’s Infinity Circuit. There it will exist for all eternity as part of a gestalt collective mind of the dead. The Dark Eldar take a predictably more savage course. They are partially protected by their existence within the Labyrinthine Dimension of the Webway from consumption by Slaanesh, but “She Who Thirsts” will eventually consume even a Dark Eldar’s soul unless he draws psychic energy to protect himself from the psychic agony of others. It is for this reason that the Dark Eldar are such malevolent creatures, seeking out an endless supply of slaves whose torture they not only enjoy but which actually keeps their twisted souls intact.

Amongst the mortal servants of the Chaos Gods, there is no doubt: when a mortal dies in realspace, his soul is immediately swept into the Warp at the moment his physical body dies, where it will be devoured by the daemons and other Warp entities or made into their pitiable plaything for all eternity. The only salvation from this grim fate is to give oneself over body and soul to the worship and service of the Ruinous Powers either collectively as Chaos Undivided or individually as the Dark Gods may grant their more successful and powerful followers a favoured place within the Realm of Chaos upon their deaths. The most successful devotees of Chaos can even look forward to an existence as a Daemon Prince, a position of guaranteed immortality and control over one’s own small demesne or Daemon World within the Realm of Chaos or a Warp Rift like the Eye of Terror.

The devotees of many variants of the Imperium of Man’s Imperial Cult also believe that when a person dies, his soul is transported to the Warp. But a devout worshipper of the God-Emperor of Mankind holds that the Emperor protects His faithful within the Warp from all entities that might seek to harm them and gathers the souls of the faithful to Himself. Only someone who has not been faithful to the Emperor and carried out His will or obeyed His commandments is at risk of being devoured by daemons of the Warp or otherwise punished within the Empyrean. In this way, the devotees of the Imperial Cult see the Warp as an analogue of the old Judeo-Christian concept of Heaven and Hell — the Warp is Hell for those who have been unfaithful to the God-Emperor, but can become a form of Heaven for those who have been true to His will. Whether there is any truth to this belief is unknown, but the psychic nature of the Empyrean means that the collective and strongly-held beliefs of mortals in realspace tend to take on a reality of their own within the Warp. And there are a great many human beings in the galaxy, and a great many of them are fervent, even fanatical believers in the Imperial Creed. What is known with certainty is that those men and women of the Imperium who have displayed unshakeable faith in their concept of the God-Emperor have sometimes been able to enact feats that can only be considered miraculous by any fair use of the term. These feats have been particularly potent when deployed as weapons against the servants of Chaos, daemonic and mortal alike. It may be possible that as the ancient credo tells us, the Emperor protects…

Warp Rifts

On rare occasions, the realm of the Immaterium is able to break out into the physical universe in what is known as a Warp Rift. A Warp Rift is a weakening of the barrier between realspace and the Empyrean, allowing its creatures to enter the material universe. Sometimes, Warp Rifts occur randomly, while other times, the Chaos Gods or mortals manufacture them. Some last mere moments, others for solar days, standard years, or even for Terran centuries. They can take many forms, often a seething whirlpool of raw psychic power, other times as a terrifying glimpse into the Realm of Chaos. They have also appeared as gates of green fire, clouds of impenetrable shadow, boiling lakes of pus, and other terrifying visions capable of driving mortals mad. These Warp Rifts are usually settled by the once-mortal followers of the Ruinous Powers of Chaos, and are often the site of titanic atrocities previously unleashed in the local region of space by these Forces of Chaos.

A number of different factors can induce the formation of a Warp Rift in realspace, including the unpredictable movements of the Warp causing a break into realspace, the daemonic possession of a mortal, deliberate rituals of daemon-summoning carried out by Chaos Cultists, a breach in the barrier between realspace and the Warp caused by the psychic focus of immense suffering and death following a great war or terrible atrocity, a Warp-Drive implosion, or as a result of the unified will of the major Chaos Gods.

The most well-known Warp Rifts in the Milky Way Galaxy include:

  • The Eye of Terror, created when the Eldar inadvertently caused the creation of Slaanesh, which is now home to the Traitor Legions of the Chaos Space Marines and their other human followers like Chaos Cultists, Traitor Imperial Guardsmen and the Hereteks and Traitor Titan Legions of the Dark Mechanicus.
  • The Maelstrom
  • The Storm of the Emperor’s Wrath (currently consuming much of the Caradryad Sector)
  • Van Grothe’s Rapidity (near the world of Medusa V)
  • Heart of Darkness (near the Attila System)
  • Hell’s Gullet (in the Berillian System)
  • The Screaming Vortex (between the Calixis Sector and the Koronus Expanse)

The Warp is an extremely volatile medium. At times, disturbances can turn areas of the Warp into raging storms of incomprehensibly destructive fury that can breach the barrier into realspace. These storms can last for solar days, months, or even standard centuries. These “Warp Storms” can isolate star systems and entire sectors from each other, by making the Imperium’s normal methods of interstellar travel and communication impossible as the Warp surrounding those regions becomes too chaotic for a starship to safely travel through or for an Astropath to send or receive a telepathic message through the psychic “interference.” These storms can last for any amount of time, ranging from solar weeks to Terran centuries, and can occasionally break out into the material universe, creating a temporary Warp rift that can result in an incursion by the Forces of Chaos into Imperial space. Starships caught in these storms are likely at best to be driven far off-course and emerge back into realspace thousands of light-years from their intended destination in uncharted areas of the galaxy. More often, such vessels find themselves trapped within the Warp, a terrible fate for its passengers as they become playthings for the dark creatures that inhabit that malign realm when their protective Gellar Field finally fails. While uncommon, some starships, after making their way through the Empyrean for only a short time, will emerge from the Warp only to find that entire Terran centuries have passed in realspace. Such an occurrence is more likely to happen when a vessel is travelling through a region of the Warp affected by a Warp Storm or unusual psychic turbulence. However, the Warp is a dangerous and chaotic place at the best of times; every use of a Warp-Drive is perilous, no matter how routine.

The Warp

Birthright DTM DTM