The Xeelee Sequence (; ) is a series of

hard science fiction Hard science fiction is a category of science fiction characterized by concern for scientific accuracy and logic. The term was first used in print in 1957 by P. Schuyler Miller in a review of John W. Campbell's ''Islands of Space'' in the Novemb ...

space opera Space opera is a subgenre of science fiction that emphasizes space warfare, with use of melodramatic, risk-taking space adventures, relationships, and chivalric romance. Set mainly or entirely in outer space, it features technological and soci ...

novel A novel is a relatively long work of narrative fiction, typically written in prose and published as a book. The present English word for a long work of prose fiction derives from the for "new", "news", or "short story of something new", itsel ...

novella A novella is a narrative prose fiction whose length is shorter than most novels, but longer than most short stories. The English word ''novella'' derives from the Italian ''novella'' meaning a short story related to true (or apparently so) facts ...

s, and

short stories A short story is a piece of prose fiction that typically can be read in one sitting and focuses on a self-contained incident or series of linked incidents, with the intent of evoking a single effect or mood. The short story is one of the oldest t ...

written by British

science fiction Science fiction (sometimes shortened to Sci-Fi or SF) is a genre of speculative fiction which typically deals with imaginative and futuristic concepts such as advanced science and technology, space exploration, time travel, parallel unive ...

author Stephen Baxter. The series spans billions of years of

fictional history Historical fiction is a literary genre in which the plot takes place in a setting related to the past events, but is fictional. Although the term is commonly used as a synonym for historical fiction literature, it can also be applied to other t ...

, centering on

humanity's future expansion into the universe Human presence in space is about humanity in space, particularly about all anthropogenic presence in space and human activity in space, that is in outer space and in a broader sense also on any extraterrestrial astronomical body. Humans have ...

, its intergalactic war with an enigmatic and supremely powerful Kardashev Type IV alien civilization called the Xeelee (eldritch symbiotes composed of spacetime defects, Bose-Einstein condensates, and

baryonic matter In particle physics, a baryon is a type of composite subatomic particle which contains an odd number of valence quarks (at least 3). Baryons belong to the hadron family of particles; hadrons are composed of quarks. Baryons are also classified ...

), and the Xeelee's own

cosmos The cosmos (, ) is another name for the Universe. Using the word ''cosmos'' implies viewing the universe as a complex and orderly system or entity. The cosmos, and understandings of the reasons for its existence and significance, are studied in ...

-spanning war with

dark matter Dark matter is a hypothetical form of matter thought to account for approximately 85% of the matter in the universe. Dark matter is called "dark" because it does not appear to interact with the electromagnetic field, which means it does not ab ...

entities called Photino Birds. The series features many other species and civilizations that play a prominent role, including the Squeem (a species of group-mind

aquatics Aquatics may refer to: *Aquatic sports in the Olympics and other international competitions, including the disciplines of swimming, diving, synchronized swimming, water polo, and open water swimming *Water-related sports more broadly (including boa ...

), the Qax (beings whose biology is based on the complex interactions of

convection cell In the field of fluid dynamics, a convection cell is the phenomenon that occurs when density differences exist within a body of liquid or gas. These density differences result in rising and/or falling currents, which are the key characteristics ...

s), and the Silver Ghosts (colonies of symbiotic organisms encased in reflective skins). Several stories in the Sequence also deal with humans and

posthuman Posthuman or post-human is a concept originating in the fields of science fiction, futurology, contemporary art, and philosophy that means a person or entity that exists in a state beyond being human. The concept aims at addressing a variety of ...

s living in extreme conditions, such as at the heart of a

neutron star A neutron star is the collapsed core of a massive supergiant star, which had a total mass of between 10 and 25 solar masses, possibly more if the star was especially metal-rich. Except for black holes and some hypothetical objects (e.g. white ...

(''

Flux Flux describes any effect that appears to pass or travel (whether it actually moves or not) through a surface or substance. Flux is a concept in applied mathematics and vector calculus which has many applications to physics. For transport ph ...

''), in a separate universe with considerably stronger

gravity In physics, gravity () is a fundamental interaction which causes mutual attraction between all things with mass or energy. Gravity is, by far, the weakest of the four fundamental interactions, approximately 1038 times weaker than the stro ...

(''

Raft A raft is any flat structure for support or transportation over water. It is usually of basic design, characterized by the absence of a hull. Rafts are usually kept afloat by using any combination of buoyant materials such as wood, sealed barrel ...

''), and within

eusocial Eusociality (from Greek εὖ ''eu'' "good" and social), the highest level of organization of sociality, is defined by the following characteristics: cooperative brood care (including care of offspring from other individuals), overlapping generat ...

hive societies (''

Coalescent ''Coalescent'' is a science-fiction novel by Stephen Baxter. It is part one of the ''Destiny's Children'' series. The story is set in two main time periods: modern Britain, when George Poole finds that he has a previously unknown sister and f ...

''). The Xeelee Sequence deals with many concepts stemming from the fringe of

theoretical physics Theoretical physics is a branch of physics that employs mathematical models and abstractions of physical objects and systems to rationalize, explain and predict natural phenomena. This is in contrast to experimental physics, which uses experim ...

and

futurology Futures studies, futures research, futurism or futurology is the systematic, interdisciplinary and holistic study of social and technological advancement, and other environmental trends, often for the purpose of exploring how people will li ...

, such as

artificial wormhole A wormhole (Einstein-Rosen bridge) is a hypothetical structure connecting disparate points in spacetime, and is based on a special Solutions of the Einstein field equations, solution of the Einstein field equations. A wormhole can be visualize ...

time travel Time travel is the concept of movement between certain points in time, analogous to movement between different points in space by an object or a person, typically with the use of a hypothetical device known as a time machine. Time travel is a w ...

, exotic-matter physics,

naked singularities In general relativity, a naked singularity is a hypothetical gravitational singularity without an event horizon. In a black hole, the singularity is completely enclosed by a boundary known as the event horizon, inside which the curvature of space ...

closed timelike curve In mathematical physics, a closed timelike curve (CTC) is a world line in a Lorentzian manifold, of a material particle in spacetime, that is "closed", returning to its starting point. This possibility was first discovered by Willem Jacob van Sto ...

s, multiple universes, hyperadvanced

computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes, and development of both hardware and software. Computing has scientific, e ...

and

artificial intelligence Artificial intelligence (AI) is intelligence—perceiving, synthesizing, and inferring information—demonstrated by machines, as opposed to intelligence displayed by animals and humans. Example tasks in which this is done include speech re ...

faster-than-light travel Faster-than-light (also FTL, superluminal or supercausal) travel and communication are the conjectural propagation of matter or information faster than the speed of light (). The special theory of relativity implies that only particles with zero ...

, spacetime engineering,

quantum wave function A wave function in quantum physics is a mathematical description of the quantum state of an isolated quantum system. The wave function is a complex number, complex-valued probability amplitude, and the probabilities for the possible results of ...

beings, and the upper echelons of the

Kardashev scale The Kardashev scale ( Russian: Шкала Кардашева, ''Shkala Kardasheva'') is a method of measuring a civilization's level of technological advancement based on the amount of energy it is able to use. The measure was proposed by S ...

. 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 Effect may refer to: * A result or change of something ** List of effects ** Cause and effect, an idiom describing causality Pharmacy and pharmacology * Drug effect, a change resulting from the administration of a drug ** Therapeutic effect, a ...

of war and

militarism Militarism is the belief or the desire of a government or a people that a state should maintain a strong military capability and to use it aggressively to expand national interests and/or values. It may also imply the glorification of the mili ...

on society. As of August 2018, the series is composed of 9 novels and 53 short pieces (short stories and novellas, with most collected in 3

anthologies In book publishing Publishing is the activity of making information, literature, music, software and other content available to the public for sale or for free. Traditionally, the term refers to the creation and distribution of printed work ...

), all of which fit into a fictional

timeline A timeline is a display of a list of events in chronological order. It is typically a graphic design showing a long bar labelled with dates paralleling it, and usually contemporaneous events. Timelines can use any suitable scale representi ...

stretching from the

Big Bang The Big Bang event is a physical theory that describes how the universe expanded from an initial state of high density and temperature. Various cosmological models of the Big Bang explain the evolution of the observable universe from the ...

's singularity of the past to the eventual

heat death of the universe The heat death of the universe (also known as the Big Chill or Big Freeze) is a hypothesis on the ultimate fate of the universe, which suggests the universe will evolve to a state of no thermodynamic free energy, and will therefore be un ...

and ''

Timelike Infinity ''Timelike Infinity'' is a 1992 science fiction book by British author Stephen Baxter. The second book in the Xeelee Sequence, ''Timelike Infinity'' introduces a universe of powerful alien species and technologies that manages to maintain a re ...

''s 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 An ebook (short for electronic book), also known as an e-book or eBook, is a book publication made available in digital form, consisting of text, images, or both, readable on the flat-panel display of computers or other electronic devices. Alt ...

format entitled ''Xeelee Sequence: The Complete Series''. Baxter's ''

Destiny's Children ''Destiny's Children'' is a science-fiction series by Stephen Baxter. It takes place within his larger series, the ''Xeelee Sequence''. Like his previous '' Manifold Trilogy'', the books are not direct sequels to one another, but are instead them ...

'' series is part of the Xeelee Sequence.

Conception

Baxter first conceived of the Xeelee while hobby writing a short story in the summer of 1986 (eventually published in ''Interzone'' as "The Xeelee Flower" the following year). He incorporated powerful off-stage aliens to explain the story's titular artifact, and in pondering the

backstory A backstory, background story, back-story, or background is a set of events invented for a plot, presented as preceding and leading up to that plot. It is a literary device of a narrative history all chronologically earlier than the narrative of p ...

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.

Plot overview

The overarching plot of the Xeelee Sequence involves an intergalactic war between humanity and the Xeelee, and a cosmic war between the Xeelee and the Photino Birds, with the latter two being alien species that originated in the

early universe The chronology of the universe describes the history and future of the universe according to Big Bang cosmology. Research published in 2015 estimates the earliest stages of the universe's existence as taking place 13.8 billion years ago, wit ...

. The technologically advanced Xeelee primarily inhabit

supermassive black hole A supermassive black hole (SMBH or sometimes SBH) is the largest type of black hole, with its mass being on the order of hundreds of thousands, or millions to billions of times the mass of the Sun (). Black holes are a class of astronomical obj ...

s, manipulating their

event horizon In astrophysics, an event horizon is a boundary beyond which events cannot affect an observer. Wolfgang Rindler coined the term in the 1950s. In 1784, John Michell proposed that gravity can be strong enough in the vicinity of massive compact obj ...

s to create preferable living environments, construction materials, tools, and computing devices. The Photino Birds are a

-based species that live in the

gravity well The Hill sphere of an astronomical body is the region in which it dominates the attraction of satellites. To be retained by a planet, a moon must have an orbit that lies within the planet's Hill sphere. That moon would, in turn, have a Hill sp ...

s of stars, who are likely not aware of

baryon In particle physics, a baryon is a type of composite subatomic particle which contains an odd number of valence quarks (at least 3). Baryons belong to the hadron family of particles; hadrons are composed of quarks. Baryons are also classified ...

ic life forms due to dark matter's weak interactions with normal matter. Due to the inevitable risk of their habitats being destroyed by

supernova A supernova is a powerful and luminous explosion of a star. It has the plural form supernovae or supernovas, and is abbreviated SN or SNe. This transient astronomical event occurs during the last evolutionary stages of a massive star or when ...

e and other consequences of

stellar evolution Stellar evolution is the process by which a star changes over the course of time. Depending on the mass of the star, its lifetime can range from a few million years for the most massive to trillions of years for the least massive, which is cons ...

, the Photino Birds work to halt

nuclear fusion Nuclear fusion is a reaction in which two or more atomic nuclei are combined to form one or more different atomic nuclei and subatomic particles ( neutrons or protons). The difference in mass between the reactants and products is manifest ...

in the cores of stars, prematurely aging them into stable

white dwarf A white dwarf is a stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very dense: its mass is comparable to the Sun's, while its volume is comparable to the Earth's. A white dwarf's faint luminosity comes fro ...

s. The resulting dwarfs provide them with suitable habitats for billions of times longer than other types of stars could, but at the expense of other forms of life on nearby planets. The Photino Birds' activities also effectively stop the formation of new black holes due to a lack of

Type II supernova A Type II supernova (plural: ''supernovae'' or ''supernovas'') results from the rapid collapse and violent explosion of a massive star. A star must have at least 8 times, but no more than 40 to 50 times, the mass of the Sun () to undergo this ...

e, threatening the existence of the Xeelee and their cosmic projects. After overcoming a series of brutal

occupations Occupation commonly refers to: *Occupation (human activity), or job, one's role in society, often a regular activity performed for payment *Occupation (protest), political demonstration by holding public or symbolic spaces *Military occupation, th ...

by extraterrestrial civilizations, humanity expands into the galaxy with an extremely

xenophobic Xenophobia () is the fear or dislike of anything which is perceived as being foreign or strange. It is an expression of perceived conflict between an in-group and out-group and may manifest in suspicion by the one of the other's activities, a ...

and militaristic outlook, with aims to exterminate other species they encounter. Humans eventually become the second-most advanced and widespread civilization in the

Milky Way The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye ...

galaxy, after the Xeelee. Unaware of the Photino–Xeelee war and the existential ramifications of what is at stake, humanity come to the (unwarranted) conclusion that the Xeelee are a sinister and destructive threat to their

hegemony Hegemony (, , ) is the political, economic, and military predominance of one State (polity), state over other states. In Ancient Greece (8th BC – AD 6th ), hegemony denoted the politico-military dominance of the ''hegemon'' city-state over oth ...

and security. Through a bitter

war of attrition The War of Attrition ( ar, حرب الاستنزاف, Ḥarb al-Istinzāf; he, מלחמת ההתשה, Milhemet haHatashah) involved fighting between Israel and Egypt, Jordan, the Palestine Liberation Organisation (PLO) and their allies from ...

, humans end up containing the Xeelee to the

galactic core The Galactic Center or Galactic Centre is the rotational center, the barycenter, of the Milky Way galaxy. Its central massive object is a supermassive black hole of about 4 million solar masses, which is called Sagittarius A*, a compact rad ...

. Both humans and the Xeelee gain

strategic intelligence Strategic intelligence (STRATINT) pertains to the collection, processing, analysis, and dissemination of intelligence that is required for forming policy and military plans at the national and international level. Much of the information needed for ...

by using

as a war tactic, through the use of

s, resulting in a stalemate for thousands of years. Eventually, humanity develops defensive, movable pocket universes to compartmentalize and process information, and an exotic weapon able to damage the ecological stability of the core's supermassive black hole. Minutes after the first successful strike, the Xeelee withdraw from the galaxy, effectively ceding the Milky Way to fully human control. Humanity continued to advance technologically for a hundred thousand years afterwards, then attacked the Xeelee across the

Local Group The Local Group is the galaxy group that includes the Milky Way. It has a total diameter of roughly , and a total mass of the order of . It consists of two collections of galaxies in a "dumbbell" shape: the Milky Way and its satellites form ...

of galaxies. However, despite having annoyed the Xeelee enough to give up activities in the Milky Way, humans, having become an extremely powerful Type III civilization themselves at this point, prove only to be a minor distraction to the Xeelee on the whole, being ultimately unable to meaningfully challenge their dominance across the universe. Although the Xeelee are masters of

space and time Space and Time or Time and Space, or ''variation'', may refer to: * ''Space and time'' or ''time and space'' or ''spacetime'', any mathematical model that combines space and time into a single interwoven continuum * Philosophy of space and time Sp ...

capable of influencing their own evolution, they are ultimately unsuccessful in stopping the Photino Birds. They instead utilize

cosmic string Cosmic strings are hypothetical 1-dimensional topological defects which may have formed during a symmetry-breaking phase transition in the early universe when the topology of the vacuum manifold associated to this symmetry breaking was not simp ...

s to build an enormous ring-like structure (which comes to be known as Bolder's Ring, or simply the Ring) to permit easy travel to other universes, allowing them and other species to escape the Photino Birds' destruction of the universe. The Xeelee, despite their unapproachable aloofness and transcendent superiority, appear to be compassionate and charitable toward the younger and less advanced species that inhabit the universe, demonstrating this by doing such things as constructing a specially-made universe suited to the Silver Ghosts, who humans had nearly driven to extinction. Humans are likewise shown compassion by them and allowed to use the Ring to escape, despite their relentless long war against the Xeelee.

Books

Xeelee Sequence main novels

Destiny's Children sub-series novels

Collections of short stories and novellas

Currently uncollected stories

Chronology and reading order

The novels in chronological order (as opposed to publication order) are given below. Some of the novels contain elements occurring at different points in the

. The story anthologies (''Vacuum Diagrams'', ''Resplendent'', and ''Xeelee: Endurance'') each contain stories taking place across the entire chronology. 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''."

Reception

Science fiction author

Paul J. McAuley Paul J. McAuley (born 23 April 1955) is a British botanist and science fiction author. A biologist by training, McAuley writes mostly hard science fiction. His novels dealing with themes such as biotechnology, alternative history/alternative re ...

has praised Baxter and the series, saying:

Notes

*Baxter cites the pronunciation "ch-ee-lee" in '' Xeelee: Vengeance''. It's unclear why, given the history of the author himself pronouncing it as "zee-lee", but one possible reason is that it reflects how the name came to be pronounced

in-universe A fictional universe, or fictional world, is a self-consistent setting with events, and often other elements, that differ from the real world. It may also be called an imagined, constructed, or fictional realm (or world). Fictional universes may ...

due to

language change Language change is variation over time in a language's features. It is studied in several subfields of linguistics: historical linguistics, sociolinguistics, and evolutionary linguistics. Traditional theories of historical linguistics identify ...

, especially considering Baxter's prior references to

glottochronology Glottochronology (from Attic Greek γλῶττα ''tongue, language'' and χρόνος ''time'') is the part of lexicostatistics which involves comparative linguistics and deals with the chronological relationship between languages.Sheila Embleton ( ...

in the series. *Winner of the

BSFA Award The BSFA Awards are literary awards presented annually since 1970 by the British Science Fiction Association (BSFA) to honour works in the genre of science fiction. Nominees and winners are chosen based on a vote of BSFA members. More recently, m ...

for Best Short Fiction, 2004

References

External links

* Stephen Baxter'
official website
* The complete (as of September 2015

of novels and stories, hosted on Baxter's official website. * {{Stephen Baxter, state=collapsed Book series introduced in 1991 Fictional universes Novels about extraterrestrial life Stephen Baxter series Space opera Transhumanism in fiction Artificial intelligence in fiction Artificial wormholes in fiction Fiction about consciousness transfer Fiction about immortality Fiction about the Solar System Fiction about time travel Fiction set in the 7th millennium or beyond Quantum fiction novels Dystopian novels Cosmic horror