Xeelee technology

The Xeelee are a species featured in the Xeelee Sequence series of books by British science fiction author Stephen Baxter. In this setting, the Xeelee represent the unattainable pinnacle of technological development. As a result, they are feared and envied by other star-faring Xeelee Sequence species, most of which the Xeelee themselves ignore. The only known exception is Humanity, whom the Xeelee eventually attacked and imprisoned after two long wars were fought between the two species.

The Xeelee's primary adversary was the Photino Birds, whose reshaping of the stars was opposed (ultimately futilely) by the Xeelee. When the war was lost the Xeelee retreated through the Ring and made provisions to save the younger races, including a lifeboat for Humanity to reach the eponymous Ring of Ring and escape the dying universe. In spite of their previous wars against the humans, the Xeelee did not molest the Great Northern when it escaped through the Ring carrying the last of humanity to safety in a new universe.

Xeelee technology is highly-coveted, notably by humans, who make extensive use of it to wage three futile wars against the god-like aliens. The first from 12,000-25,000 AD resulted in victory for humanity and control of the Milky Way. The second from 100,000 - 200,000 AD resulted in stalemate with man eventually giving up and returning to the Milky Way, while the third and longest began in 700,000 AD and resulted in a massive prolonged Xeelee attack named the Scourge as man was pushed back from the stars to Earth and finally into a dimensional prison around 1,000,000 AD.

Construction Material
The Xeelee use an exotic form of matter for most of their construction. Known by the generic name of "construction material", the substance is very dense, though it shares virtually no similarities to expected properties of degenerate matter such as neutronium. Instead, it appears as if the material violates the Pauli exclusion principle, allowing electrons to simultaneously share quantum states.

Construction material has been observed to be synthesized or grown from a small flower-like object, known anecdotally as the Xeelee Flower (as seen in the short story The Xeelee Flower, found in Vacuum Diagrams). This device creates construction material when the control unit is removed in the presence of sunlight. It is unknown if the Xeelee have other methods of creating the substance. The only things known to be able to damage it are magnetic monopoles and gravitational singularities. During the third human/Xeelee war the Xeelee encased stars in this material, this prevented any radiation and heat escaping and so forcing humans to leave those systems or die.

Hyperdrive
The Xeelee hyperdrive functions by moving the ship from one point in space to another instantaneously. Though the travel time between points is zero, there is a short pause between each jump required to compute the parameters of the next jump. This pause was a couple seconds when a Xeelee Nightfighter was flown by Jim Bolder. However, it is implied that Xeelee pilots operate their craft more efficiently. This hyperdrive can cross at least 100 parsecs in a single jump if required, however the Xeelee have been known to use much smaller jumps tactically, even in combat. The hyperdrive does not rely on the craft being entirely made of Xeelee construction material, as an instance of one jumping with another ship tied to its back was shown in The Ring.

Discontinuity Drive
The Discontinuity Drive used by Xeelee Nightfighters directly pushes on Spacetime. This is done by a pair of extremely large "wings" that can extend from the Sycamore seed shaped Nightfighter. These wings are not made of typical Xeelee construction material, but are constructs of pure spacetime and in this way they can directly exchange momentum with the fabric of the universe itself. The means by which the wings interface with the degenerate matter Nightfighter cockpit is unknown, but it is suggested that this may be a fundamental aspect of Xeelee physiology and/or technology. The wings appear jet black and seem to be at least as durable as the cockpit.

The discontinuity drive is capable of tremendous accelerations, and is observed to allow a Nightfighter some degree of maneuverability even near the surface of a Neutron Star. This suggests accelerations on the order of 10^12 - 10^13 m/s^2, allowing the Nighfighter to go from a dead stop to near the speed of light in about 100 microseconds. It is also suggested that the Xeelee ships perform better in regions of highly curved spacetime, so their accelerations in flat space may be a couple orders of magnitude lower.

Starbreaker
The starbreaker is the primary weapon used by the Xeelee. It has only been observed in use on the nightfighter starships. The starbreaker is a gravity wave laser that has the ability to destroy a star. The starbreaker was first observed in the short story Blue Shift (Vacuum Diagrams). In this story, the Qax (another alien race that has conquered Man) have found a damaged nightfighter. The only thing aboard is a small object that is similar to a handgun with delicate wire wrapped around the barrel, and controls described as being for hands smaller than a human's.

At low power settings, the device emits synchrotron radiation, but the Qax have been too scared to try the higher settings. It is not until later in the story when Jim Bolder, piloting the nightfighter for the Qax, discovers the true nature of the device when he witnesses a small fleet of nightfighters destroying a star with cherry-red beams. After hatching a plot to change his entry point into the Qax system, this theory is proven when the starbreaker is accidentally fired into the system's sun at full power in an attempt to destroy the nightfighter. The star begins destroying itself within four days.

Time Travel
Time travel is an integral component to the Xeelee civilization, as they have self-created as a closed timelike curve. White cube-shaped devices were found throughout Xeelee-controlled space as Man expanded. The function of these devices was unknown until the Xeelee activated them, and they vanished backwards in time. Led by the quantum-mechanical anti-Xeelee, this temporal migration had a specific goal: to engineer the Xeelee's early development, and to give them a leg up so that they could complete their great project.

The Xeelee have also been known to travel through time by using their Hyperdrive and very efficient Discontinuity Drive to assemble closed timelike curves. They have been known to use this tactic in the war against Humanity to carry information about a battle backwards in time so it can be used to their advantage during the battle. Future foreknowledge gained from time travel is consistently used by not only the Xeelee but also the Humans, preventing its use from immediately deciding the conflict.

The Ring
Arguably the ultimate expression of the Xeelee's technological prowess, the object known as Bolder's Ring or simply the Ring was long a source of wonder and mystery.

When Jim Bolder flew to the Great Attractor in the Qax's captured nightfighter, what he found was astonishing. All matter in the universe was falling towards the object's massive gravity well. Even more astounding, this object and indeed the entire motion of the galaxies themselves appeared to be the work of the Xeelee, who were using the mass to create a ring of cosmic strings several million light years in diameter.

The purpose of the device was a mystery, but it was assumed the Xeelee's intent was hostile and that they were effectively destroying the universe for their own ends. Indeed, it was this assumption in part that led to Man's species imperative to wage a million-year war to defeat the Xeelee at all costs.

It was only after Humanity's ultimate defeat that the sad remnants of the species would discover the truth. The Ring was not a battleship, or a fortress, or a weapon. The Ring was an escape hatch, with the naked singularity at its center providing access to other universes. The Xeelee had been waging an eons-long war against an opponent that even they could not beat, not even with the ability to engineer time itself. Their last resort had been to build the Ring to escape before the ultimate death of the universe.

Only three groups of humans were known to have escaped through the Ring. The humans of the generational GUTship Great Northern, escaped into a new young universe after being displaced five million years into the future, and the last human refugees of the hypersphere prison that held Man after their defeat by the Xeelee. The Xeelee proved themselves to have at least some compassion towards their baryonic kindred in the latter case, by leaving a partially sentient starship to carry the humans away. During the war one ship crashed through the ring arriving in a universe with ultra high gravity. The crew survived and the novel Raft recounts some of their history.

The Ring itself was ultimately destroyed by the Photino Birds. They had set in motion a radio-frequency amplification effect, a bomb of sorts that would disrupt the Ring after reaching critical levels in several million years. However this gradual destruction was vastly accelerated due to the Photino Birds being tricked into thinking the Xeelee had returned, and the retaliatory star-strike conducted by the Qax in an attempt to halt them. The cosmic strings that composed the ring would cut if they self-intersected, creating a chain reaction that would ultimately destroy the entire Ring.

Sugar Lumps
Nearing the end of their work on the Ring, roughly 4 million years from the present, the Xeelee constructed several hundreds of enclosures to return to the beginning of their history 13.5 billion years ago. These enclosures, call Sugar Lumps, appeared as enormous glowing cubes varying in size from a few thousand to tens of thousands of kilometers on a side (capable of enclosing moons or planets). More than a simple Closed Timelike Curve, the Sugar Lumps are described as having a negative vector in time (i.e. traveling backwards in time via a time symmetry) and function as inverse time capsules. When the Sugar Lumps arrive at their destination in the distant past, the Xeelee would emerge as a fully developed race with their knowledge of future events and be able to immediately initiate their grandest projects against the Photino Birds.

The Sugar Lumps are guided both in management of their travel and coordination of their effort, by the Anti-Xeelee. Use of the Sugar Lumps enabled the Xeelee to consciously manage their own evolution as well as make any necessary edits to the history of the universe so that their projects are unopposed to the maximum extent possible. It is therefore likely that any species which made a substantial rivalry with the Xeelee were prevented from evolving in the first place, and further that the Xeelee were unable to prevent the evolution of the Photino Birds.

Miscellaneous

 * Earth's Hypersphere
 * Quantum Inseparability Communications
 * Gravity Manipulating Device
 * Quagma Ark