Warp (Warhammer 40000)

The Warp
According to the Warhammer 40000 fictional series, The Warp is considered to be a parallel universe which is the home for the ruinous Chaos powers and their dark gods. The Warp is very different from the Material universe. It is a kind of pathway that is used when travelling between different sectors or systems. While it is a useful tool for inter-sector and intra-galactic travel, it has its own dangers. It is also known as the Immaterium.

The Home of Chaos
Although Chaos are found to be predominantly present in the region known as the Eye of Terror, the real home of Chaos is the Warp. It is a place where everything lays disorderly, and mostly terrifying. The Chaos Gods reside in their own strongholds within the Warp from which they send out demons and other servants to spot for any worlds that are engulfed or found vulnerable to be attacked by the Warp.

Dangers of the Warp
The Warp is a dangerous place for any organism that has a sane mind. The bewildering psychic energies torture the minds of any who lay susceptible to the Warp. Even the most powerful Librarians and Psykers couldn't be able to withstand the torments of the Warp without proper protection. This is why Warp travel is considered to be dangerous. It is also the reason that The Imperium of Man is not able to wipe out Chaos completely as human forces sent into the Warp couldn't last too long before succumbing to its corruption. Also the presence of demons and other Chaotic creatures make it a very hostile environment.

Protection from the effects of the Warp
The best mechanism to protect oneself from the Warp is to avoid warp travel altogether and find an alternative. But only very few races could do this, namely, the Eldar, Tyranids, Necrons. The Eldar use Webways as an alternative to Warp Travel, as Webways are a quicker means of travel than the Warp and that its free from the demonic forces of Chaos. The Necrons do not use the Warp as well. They travel by means of their unknown phase technology to move around the galaxy, which means they have no need of any protection mechanism. The Tyranids also don't travel through the Warp, instead, they use Bio-Ships called "Narvhals" that manipulate their intended destination's own gravity to compress realspace into a type of gravitic transit corridor or worm hole, allowing the Hive Fleets to cover vast distances very quickly. The mechanism that Orks use is still a mystery. But it is generally agreed that concentration of Orks psychic powers could generate a shield against the powers of the Warp. The Tau do not directly travel through the Warp, instead they use a process known as Warp Diving, in which they travel between sectors by diving into the boundary between the warpspace and real-space at definite intervals for recharging power. And finally, the Imperium of Man accomplishes the Warp travel and protects its fleets by a special field known as the Gellar Field. It creates a shield of realspace or a real time barrier around the ships. Its an invisible field and due to this realtime field, the warp creatures are repelled due to their contradiction with the realspace or the Materium.

Shadow across the Warp
Casting a Shadow across the Warp is a power belonging to the Tyrannids. When the Hive fleets pick their targets and engage them, the Hive Mind will direct its fleets through its psychic powers. So, due to the presence of the strong, immense psychic powers of the Hive Mind, it would make the sections of the Warp unfit for travel. No other fleets could travel through that region. Thus, sectors which are under the attack of Tyrannids are often lost if not garissoned properly, as the psychic power of the Hive Mind makes it impossible for reinforcements to arrive from distant sectors. The Hive Mind could thus isolate entire sectors and systems from the rest of the Galaxy, thereby casting a shadow and thus the name "Shadow across the Warp".