The Xeelee Sequence (//; ZEE-lee) is a series of hard science fiction space opera novels, novellas, and short stories written by British science fiction author Stephen Baxter. The series spans billions of years of fictional history, centering on humanity's future expansion into the universe, its cosmos-spanning war with an enigmatic and supremely powerful Type IV alien civilization called the Xeelee, and the Xeelee's own war with dark matter entities called Photino Birds (also referred to as Photino Fish in the newest novel in the sequence, Redemption). The series features many other species and civilizations that play a prominent role, including the Squeem (a species of group mind aquatics), the Qax (beings whose biology is based on the complex interactions of convection cells), and the Silver Ghosts (symbiotic organisms encased in reflective shells). Several stories in the Sequence also deal with humans and posthumans living in extreme conditions, such as at the heart of a neutron star (Flux), in a separate universe with considerably stronger gravity (Raft), and within eusocial hive societies (Coalescent).
The Xeelee Sequence treats ideas stemming from the fringe of theoretical physics and futurology, such as exotic-matter physics, naked singularities, closed timelike curves, multiple universes, hyperadvanced computing and artificial intelligence, faster-than-light travel, and the upper echelons of the Kardashev scale. Thematically, the series deals heavily with certain existential and social philosophical issues, such as striving for survival and relevance in a harsh and unknowable universe and the effects of war and militarism on society.
As of August 2018, the series is composed of nine novels and 53 short pieces (short stories and novellas), all of which fit into a fictional timeline stretching from the Big Bang singularity of the past to the eventual heat death of the universe and Timelike Infinity singularity of the future. An omnibus edition of the first four Xeelee novels (Raft, Timelike Infinity, Flux, and Ring), entitled Xeelee: An Omnibus, was released in January 2010. In August 2016, the entire series of all novels and stories (up to that date) was released as one volume in e-book format entitled Xeelee Sequence: The Complete Series. Baxter's Destiny's Children series is part of the Xeelee Sequence.
Baxter first conceived of the Xeelee while hobby writing a short story in the summer of 1986 (that would later be published in Interzone as "The Xeelee Flower" in 1987). He incorporated powerful off-stage aliens to explain the story’s titular artifact, and in pondering the backstory began to flesh out the basics of what would later become the main players and setting of the Sequence: a universe full of intelligent species that live in the shadow of the incomprehensible and god-like Xeelee.
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In the Xeelee sequence life and intelligence are ubiquitous throughout the universe. The universe has a fundamental tendency towards complexity and autocatalystic systems are easily created. This is not limited to the subject matter, but also applies to such structures as these, to quarks, and to flaws in space-time itself. Thus, the life of the world was extremely young, to within Plank Time of the Big Bang, and there were intelligent civilizations that witnessed, and indeed consciously influenced, major events in the early universe such as inflationary expansion, symmetry breaking, and various phases. exchange. At the close of each of these epochs, there is a corresponding difference in the subject of mass extinction, but small enclaves of the intelligences would survive in one way or another, witnessing the universe becoming progressively colder and slower-reacting .
The novel Exultant describes the progenitor of the Xeelee, referred to as the proto-Xeelee, as one of the few survivors of the last phase change (when the universe had cooled enough for atoms to form). The proto-Xeelee established symbiotic relationships with other survivors as well as autocatalystic reactions in the new baryonic matter, thus emerging what would later be called the Xeelee. This book is only one of a hundred thousand years old, but with a few comments on the subject.
The Xeelee uses primordial black holes as a habitat, construction tool, and computing devices because, at the time they emerged, the event horizon was one of the few things that they understood. More so, heavier atoms have been exceedingly rare because of nuclear fusion. As the primordial black holes are evaporated over time the Xeelee eventually migrated to the supermassive black holes around which Galaxies were forming. Although the galactic black holes have been trillions of times more massive than their ancestral homes, the Xeelee proved to be quite adept at using the complex physics around the event horizon for their own purposes. Over the billions of years of their migration, the Xeelee have become ubiquitous part of the complex ecology of the super massive black holes along with a number of other species that are also veterans of the same very early eras of the universe.
There is no explicit physical description of the Xeelee throughout the series. In the novel Exultant it is alluded to that that they have been exceedingly long-lived, that they have combined their own technology and, as such, may have a distinct individual presence that would be familiar with.
The Photino Birds are a species of dark matter. In general, the photoinjects are probably unaware of almost all other forms of life, which is extremely difficult to interact with (eg, normal matter that is composed of atoms). The Photino Birds recognize a risk to their habitats from supernovas and other consequences of normal stellar evolution and have set themselves to cease nuclear fusion in the cores of stars, thus prematurely aging them into white dwarves. The resulting dwarves will have the same gravity well but be stable for their predecessors.Because white dwarves are extremely cold compared to typical stars, they would not support life on nearby planets. The long project of the Photino Birds will ultimately make the universe hostile to baryonic life, and they have spread across the universe. Further, the activities of the Photino Birds will effectively halt formation of new black holes due to a lack of Type II (core-collapse) supernova. This effectively puts the Xeelee and the Photino Birds at an irreparable odds because each species is fundamentally seeking to threaten the ideal habitat of the other.
The Xeelee became aware of the Photino Birds approximately 13.5 billion years ago. Seemingly a unified species, the Xeelee have concerned themselves with defeating the Photino Birds for the entire history of the universe. Despite their state of high advancement, the Xeelee were ultimately unsuccessful.
While recovering from a brutal occupation by the Qax that enforced stagnation and flirted with extinction,Humanity adopted an extremely xenophobic imperative that aims to ensure the future of the species (known as Druz Doctrines after its founder, Hama Druz). Eventually Humanity again began to expand on the galaxy, wiping out any other species encountered during their advance. Eventually Humans became the second most advanced and widespread race in the galaxy, second only to the Xeelee. Humans had no knowledge of the Photino-Xeelee war or even what was at stake, making the Xeelee seem inherently sinister. Building the Ring had the appearance of being destructive of a galactic scale because of its larger purpose, and many smaller Xeelee projects, such as changing the orbit of Callisto to preserve the bacteria, lacked an obvious explanation. Though there were several orders of magnitude fewer Xeelee than other known species in the Galaxy, their high degree of advancement made them a formidable enemy.
Through a bitter war of attrition, Humans eventually became the Xeelee within the Galactic Core where the battle lines stagnated for at least three thousand years. Both humans and the Xeelee have gained strategic control by closing Timelike Curves, further contributing to stagnation. Human casualties were estimated to exceed 10 trillion per year and more than 30 trillion over the full course of the assault. The imperative commitment to total war also stagnated human physical and intellectual evolution. The Druz Doctrines did not encourage exploration, and there was little new development.
Eventually, the Humans developed a way of hiding their actions from the Xeelee by making movable pocket universes that had no causal relationship to the universe as a whole, thus eliminating any advantage of moving information into the past. Humans also developed counter-Xeelee measures like Tactical Analysis (which gave pilots tactical information for defeating Xeelee Manouevres) and a dual black-hole cannon that could fire two singularities to merge at a known distance away, releasing enormous gravity waves in the process. Knowing that the ecology around the event horizon and the creatures that it would be damaged or destroyed if humans continued to batter the horizon of the supermassive black hole, the Xeelee withdrew from the Milky Way just minutes after the humans scored their first successful hit.
Humanity, once it no longer has the Xeelee as a unifying threat, fragments into multiple governments over the next several hundred years, though this brief period ends in the collapse of doctrinal stagnation and 100,000 years of technological advance. Humanity then unifies again to directly attack the concentrations of Xeelee concentration in the greater super-cluster of galaxies across the local group (though in the end, they prove only a slight annoyance or distraction to the Xeelee, whose energy is focused on fighting the Photino birds).
The Xeelee were seldom warlike and usually treated young species with disinterest. There are very few reported instances of them initiating interaction with another species. Those few interactions, however, were compassionate and charitable, often helping species escape the Photino Birds' destruction of the universe. In the conclusion to Baxter's novel Ring, set 5 million years in the future, the Xeelee did not interfere with the humans' escape to another world, and they even construct an entire universe for the sake of the Silver Ghosts, a species thought by humans to be extinct. Before their own retreat from the universe, the Xeelee left ships as 'life boats' at various locations so that other species could use them to escape the Photino Birds through the Ring.
The Xeelee were masters of time and space. They crafted their starships, known as Nightfighters, out of a strange form of matter that seems to violate the Pauli Exclusion Principle (which states that no two fermions can occupy the same quantum state). The material is incredibly sharp, hard, and transparent; due to its unique spacetime construction, it has strange gravitational effects.
Starbreakers are beams of coherent gravitational waves that the Xeelee use as both weapons and tools. They are consistently described as thin beams of red light that emit from Nightfighters and other Xeelee vessels encountered around Bolder's Ring. In the short story Blue Shift, the source of a Starbreaker is described as a pistol-like device designed for a hands of the size of a human child's. There is intricate wiring around the handle and an adjustment knob on the back. It will emit synchrotron radiation on the lowest setting, suggesting that it is powered by some form of particle acceleration.
Nearing the end of their work on the Ring, roughly 4 million years ago, the Xeelee built several hundred enclosures to return to the beginning of their history 20 billion years ago. These enclosures, called Sugar Lumps, appear as enormous cubes varying in size from a few thousand to one kilometer 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 arrived at their destination in the distant past, the Xeelee would emerge as a fully developed breed with their knowledge of future events and be able to immediately initiate their grandest projects against the Photino Birds.
Use of the Sugar Lumps allows the user to consciously manage their own evolution, and the evolution of other species. as much as possible to the extent possible. It is therefore likely that the Xeelee were unable to prevent the evolution of the Photino Birds.
The Xeelee's greatest achievement — possibly the greatest structure of baryonic matter ever made — is the Ring, a gigantic loop of cosmic string millions of light-years across and spinning at close to light speed. Because of its intense gravitation and spinning, it creates a tear in the universe at its center, allowing ships to pass through and enter another universe.
Xeelee Sequence main novels:
|Raft||1991||Nominated for the 1992 Arthur C. Clarke Award and Locus Award for Best First Novel.|
|Vacuum Diagrams||1997||A collection of short work (see below).|
|Xeelee: Endurance||2015||A collection of short work (see below).|
Destiny's Children sub-series novels:
|Coalescent||2003||Arthur C. Clarke Award nominee, 2004.|
|Transcendent||2005||John W. Campbell Memorial Award nominee, 2006.|
|Resplendent||2006||A collection of short work (see below).|
Collections of short stories and novellas:
|Title||Year Published||Stories Contained (numbers in parentheses indicate the year in which each piece was first separately published)||Notes|
||Philip K. Dick Award winner, 1999.|
Currently uncollected stories:
|Title and Year Published||Source of First Publication||Notes|
|"The Venus Generations" (2016)||Bridging Infinity, edited by Jonathan Strahan.|
Chronology and reading order
The novels in chronological order (as opposed to publication order) are given below. It should be noted that some of the novels contain elements occurring at different points in the timeline. The story anthologies (Vacuum Diagrams, Resplendent, and Xeelee: Endurance) contain stories taking place across the entire chronology.
|Title||Year Published||Year(s) in Story||Notes|
|Coalescent||2003||AD 476-2005||Part 1 of Destiny's Children.|
|Transcendent||2005||AD 2047||Part 3 of Destiny's Children. The world of Michael Poole Bazalget.|
|Xeelee: Vengeance||2017||AD 3646-3665||Set in an alternate timeline.|
|Xeelee: Redemption||2018||AD 4106 - c.AD 5,000,000,000||Set in the same alternate timeline as Xeelee: Vengeance.|
|Timelike Infinity||1992||AD 3717||Majority of the plot concerns events that begin here, with later major events occurring in AD 3829 and the AD 5000s. The final chapter takes place mainly in c.AD 5,000,000.|
|Ring||1994||AD 3951||Before Great Northern launches.|
|Exultant||2004||AD 24973||Part 2 of Destiny's Children.|
|Transcendent||2005||c.AD 500,000||Part 3 of Destiny's Children. The world of Alia.|
|Ring||1994||c.AD 5,000,000||After Great Northern returns.|
In 2009, Baxter posted a detailed chronology of the Xeelee Sequence explaining the proper chronological reading order of all the novels, novellas, and short stories up to that year. The timeline was updated in September 2015.
When asked directly for a suggested reading order, the author wrote: "I hope that all the books and indeed the stories can be read stand-alone. I’m not a great fan of books that end with cliff-hangers. So you could go in anywhere. One way would be to start with ‘Vacuum Diagrams’, a collection that sets out the overall story of the universe. Then ‘Timelike Infinity’ and ‘Ring’ which tell the story of Michael Poole, then ‘Raft’ and ‘Flux’ which are really incidents against the wider background, and finally ‘Destiny’s Children.’"
Science fiction author Paul McAuley has praised Baxter and the series, saying:
Baxter doesn’t shrink from tackling the dismayingly inhuman implications of vast abysses of past or future time, but the universality of life introduces perspective, motion and plot into every part of his Stapledonian cosmological framework.
It is great, heady, mind-bending stuff, meticulously mapped onto cutting edge speculations about the birth pangs of the universe and the ultimate fate of all known time and space, constantly enlivened and driven forward by the narratives that its vast range of life generates.
[It represents an] accomplished and imaginative exploration, expansion and reworking of SF’s core themes. His characters contest for living space with a panoply of bizarre aliens in a galaxy crammed with ancient wonders and secret histories; his stories reinvent the baroque excesses of space opera and brace them with imaginative exploration of ideas from stellar zoology, cosmology, quantum theory, exotic mathematics, and much else. Narratives froth with moments of shock and awe, and those sudden reversals of scale that induce the metaphysical dizziness sometimes called sense of wonder. Sentences stride confidently across centuries; paragraphs encompass millennia. Individual voices carry the story forwards, but the story is always bigger than the individuals that are caught up in it.
- "Stephen Baxter Lecture". Youtube.com.
- "Stephen Baxter Interview". Youtube.com.
- "Abusing the Kardashev Scale for Fun and Profit". TVtropes.org.
- "Flux". Amazon.co.uk. Retrieved 29 January 2017.
- "Raft". Amazon.com. Retrieved 5 September 2016.
- "Coalescent". Amazon.co.uk. Retrieved 29 January 2017.
- "Orionbooks.co.uk - Xeelee Sequence". Gollancz. Retrieved 22 March 2017.
- "The origin of the Destiny's Children series". stephen-baxter.com. Retrieved 28 August 2016.
- "The Xeelee Sequence – Timeline". stephen-baxter.com. Retrieved 29 September 2011.
- "Books". stephen-baxter.com. Retrieved 1 March 2012.
- "Orionbooks.co.uk - Xeelee Sequence". Gollancz. Retrieved 29 January 2017.
- "The Origin of the Xeelee Universe". stephen-baxter.com. Retrieved 1 April 2016.
- "1992 Award Winners & Nominees". Worlds Without End. Retrieved 3 August 2009.
- "Orionbooks.co.uk - Xeelee: Vengeance". Gollancz. Retrieved 29 January 2017.
- "Orionbooks.co.uk - Xeelee: Redemption". Gollancz. Retrieved 21 April 2018.
- "2004 Award Winners & Nominees". Worlds Without End. Retrieved 3 August 2009.
- "2006 Award Winners & Nominees". Worlds Without End. Retrieved 3 August 2009.
- "1999 PKD Award Winners & Nominees". Worlds Without End. Retrieved 28 August 2016.
- "BSFA Awards - Previous Award Winners". British Science Fiction Association. Retrieved 28 August 2016.
- "Stephen Baxter on "The Venus Generations"". Coode Street. Retrieved 18 April 2017.
- "The Xeelee Sequence - Timeline". stephen-baxter.com.
- "Fiction Excerpts and Interviews". themanifold.co.uk. Archived from the original on 2 October 2006.
- McAuley, Paul (January 2010). "Introduction". In Baxter, Stephen. Xeelee: An Omnibus. Gollancz. pp. viii–ix. ISBN 978-0575090415.