A young lunar scientist, Nemoto, invites Reid Malenfant, champion of space colonization and organizer of a failed attempt to launch an asteroid mining enterprise, to the moon to show him mysterious sources of infrared she's discovered in the asteroid belt--incontrovertible proof of aliens at last. After all manner of signals and even a probe fail to elicit a response from the aliens, who come to be called Gaijin, Malenfant sets off for the source of the wave of aliens, the solar focus of Alpha Centauri. This is only the start of a journey across the galaxy, as he and others struggle to understand why signs of intelligent life are appearing all over the galaxy ''now'' and what happened to all the previous waves of colonization soon apparent even in humanity's own solar system, while humanity itself struggles to survive against draining resources, war, and destructive waves of alien colonists.

Part of Creator/StephenBaxter's ''Manifold'' series.
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!!This book provides examples of:
* AlienSea: The Gaijin homeworld has a sea made of yellow, bubbling iron carbonyl and nickel carbonyl.
* AlternateContinuity: To the other books in the ''Manifold'' series.
* ApocalypseHow: [[spoiler:X-3, with all complex life in the galaxy periodically sterilized by the massive bursts of radiation from colliding neutron stars.]]
* ArcWords: "Where ''is'' everybody?"
* BrainFood: The [[spoiler:reconstructed ''Homo erectus'']] Magassa is seen eating the brain of his [[spoiler:''H. habilis'']] prey.
* ColonyDrop: Nemoto's plan to slam Neptune's satellite Nereid with another moon, Triton, to melt the ice so [[spoiler:the human colonists can make use of the liquid water and the Gaijin can't use the materials for their projects]].
* CompoundInterestTimeTravelGambit: Used by interstellar travelers, who are frozen in time while traveling through the portal network. It works at first, but laws are eventually passed and assets seized, leaving the travelers flat broke when they return.
* CurbStompBattle: [[spoiler:The massacre of the Cracker fleet over Mercury. The Crackers are obliterated by a volley of rocks propelled to many times Mercury's escape velocity by Nemoto's genetically engineered Moon flowers, with nobody even to fire back at, no way to avoid the rising storm of rock and dust. All that it takes for the humans are one thousand seconds and zero lives lost, with everyone being hidden safe underground]].
* DistantFinale: The epilogue, a billion years after the last chapter, seems to suggest that [[spoiler: the plan worked, and the next iteration of the Reboot cycle was postponed or avoided entirely, allowing life to flourish. Madeleine Meacher wakes up in a Gaijin habitat orbiting a ''Quasar'', and realizes that if the Gaijin survived, maybe so did the humans. And even if they didn't ''life'' itself was free from the cycle and had spread to distant galaxies]].
* DoomedHometown: Earth. [[spoiler:The onset of another Ice Age results in the collapse of civilisation, causing most humans to live as if it was the Stone Age again]].
* DopeSlap: Malenfant is repeatedly smacked on the head by superstrong Neanderthals for speaking at all. Turns out that nearly all of their language is sign, with a few super-special vocal words. The Neanderthals give him a sign-name that means "Stupid".
* FeelNoPain: One of the side effects of Saddle Point travelling is the Discontinuity, which damages the central reticular formation in the brain, causing the perception of pain to disappear.
* FlingALightIntoTheFuture: [[spoiler:At the end of the book, a coalition of aliens (including the Gaijin) are working on a mammoth solar sail designed to prevent two neutron stars from colliding and sterilizing the galaxy... except there's ''another'' collision--too late to prevent--that's going to occur first, killing the current generation. And the sail they're working on is leftover from a ''previous'' cycle.]]
* FossilRevival: One of the Gaijin's experiments following their arrival on Earth is the revival of extinct animals.
* FuturePrimitive: By 2240, following the onset of another Ice Age, the humans of Earth have reverted to a primitive existence like in the Stone Age.
* TheGhost: Individual Crackers are never seen, only their ships.
* GratuitousForeignLanguage: Japanese, Russian or Yolngu words tend to pop up every now and then in scenes involving native speakers of these languages.
* HeroicSacrifice: [[spoiler:At the end of the book, Malenfant sacrifices his very humanity--becoming some sort of pain-wracked hivemind program getting refreshed over and over again--in order to supervise the construction of the solar sail over millions of years.]]
* HiveMind: The Gaijin have little in the way of self and frequently temporarily merge together for debates.
* HollowWorld: The newly-discovered moonlet of Venus, which was dug out by aliens and thrown into orbit.
* HumanSubspecies: The Flips of the oceans of Triton in 3793 AD are dolphin-like posthuman creatures descended from human colonists who moved off the land and settled in the oceans.
* ImAHumanitarian: The human colonists of the Moon in the 4th millennium eat a soup made from the dissolved bones and flesh of the dead after one of their own dies.
* InterspeciesRomance: Mtesa, the Kabaka of Waganda, has a [[spoiler:''Homo erectus'']] concubine.
* MacrossMissileMassacre: [[spoiler:Nemoto seeds Mercury with re-engineered lunar flowers, which fire rocket-propelled seed pods. Once the entire Cracker fleet is in orbit around the planet, they simultaneously fire all pods into the sky, causing the obliteration of the '''entire''' fleet.]]
* MechanicalEvolution: The Gaijin are subject to this, with errors creeping in with each replication. [[spoiler:A visit to their homeworld confirms that they were never built by anyone else but really did naturally evolve from scratch in an exotic iron-based ecology.]]
* MechanicalLifeforms: The Gaijin might count, being iron-based lifeforms, [[spoiler:though they were not built but evolved naturally by themselves]].
* MerlinSickness: The sentient lunar flowers. They even proliferate backwards, with seed pods converging until eventually there's only one plant left. It's... odd.
* NiceJobBreakingItHero: Madeleine Meacher finds lichen-like creatures inhabiting a burster, where hydrogen from its companion star fuses when it hits the neutron star, wiping out everything on the surface, forcing the creatures to survive through 'spores' deposited under the surface and preventing them from achieving complexity. After her decision to disrupt the hydrogen flow and stop the fusion fires, the creatures surge to new parts of the world... only to die out later, as the fusion cycle is seemingly necessary to their growth in some way the humans can't understand.
* TheNightThatNeverEnds: Malenfant comes upon such a planet in his journey, where the indigenous lifeforms live off the geothermal heat in oceans of liquid water under the lightless sky.
* NumberedHomeworld: The Gaijin refer to their homeworld as Zero-zero-zero-zero and use a fluid, location-descriptive naming system for all other systems they expand to, which suits their mechanical nature.
* OrionDrive: How Malenfant reaches the portal in our solar system.
* PlanetLooters: The galaxy has been picked over by all kinds of looters many times over. [[spoiler:Venus, for instance, used to be a hospitable place until an acid-based species spun down the planet, triggered a runaway greenhouse reaction to generate acid to farm, and broke up Venus's moon to make more ships.]]
* PlanetOfHats: Humans are the only species able to devote themselves entirely to an idea (i.e. have faith), which becomes critical by the end of the book.
* PortalNetwork: The Saddle Point network. {{Precursors}} scattered portals at solar focus points throughout the galaxy that use quantum teleportation, which limits travel speed (to lightspeed) and total number of uses.
* PreciousPhoto: Malenfant keeps a photo of his wife Emma Stoney (who has already died before the start of the book in this AlternateContinuity) throughout his travels during the entire story.
* ProjectedMan - See VirtualGhost.
* RecursivePrecursors: [[spoiler:Every few hundred million years there's a gamma ray burst powerful enough, or well-directed enough, to wipe the whole of the Galaxy clean.]]
-->[[spoiler:''This is the equilibrium state for life and mind: a Galaxy full of new, young species struggling out from their home worlds, consumed by fear and hatred, burning their way across the nearby stars, stamping over the rubble of their forgotten predecessors.'']]
* RockBeatsLaser: Despite their advanced and sophisticated tech (they manage to, among others, [[spoiler:defeat the Gaijin colony in the Solar System and make stars go nova]]), the [[spoiler:Crackers are ultimately defeated by humans with nothing more than rocket-propelled rocks]].
* SapientEatSapient: The reconstructed [[spoiler:''Homo erectus'']] of the 33rd century don't really care if the prey they are hunting are [[spoiler:reconstructed australopithecines or ''Homo habilis'']].
* TheSlowPath: While other characters travel into the far future through use of the portals, experiencing no time subjectively, Nemoto persists in real time through combination of advanced medical treatments and sheer force of will, building up influence and manipulating humanity from the shadows.
* SmartPeopleKnowLatin: Latin is the language used for communication between humans and Gaijin.
* TheSpeechless: The [[spoiler:Neanderthals]] cannot speak due to their mouth structure.
* StarfishAliens:
** Each Gaijin consists of a dodecahedral central unit, with limbs sprouting in a variety of configurations, apparently specialised.
** A Chaera resembles a translucent disc about a metre across, swimming in oxygen-blue fluid like a ray.
* SuicideAttack: Pierre de Bonneville takes his revenge on his captors by sabotaging the coolant system of the Engine of Kimera (which is actually a nuclear reactor), causing a catastrophic nuclear accident in the process. No points for guessing if he survives or not.
* {{Teleportation}}: How the Saddle Point gateways work.
-->''What the builders must have done is send over the receiver gate -- the hoop Malenfant found -- by some conventional means, a slower-than-light craft like a flower-ship. The gate is EPR-correlated with another object back home, a transmitter. The transmitter makes a joint measurement on itself and the unknown quantum system of the object to be teleported. The transmitter then sends the receiver gate the classical result of the measurement. Knowing this, the receiver can convert the state of its EPR twin into an exact replica of the unknown quantum state at the transmitter...''
* TooImportantToWalk: [[TheEmperor Mtesa]] is carried around on a throne by a group of labourers.
* TreeVessel: The genetically-engineered Trees, used by a group of human colonists of 3256 AD as ports, observation platforms and resorts. The bulk of a Tree is a green ball of branches and leaves, while the trunk is hollowed out and sealed with resin to house humans. Each Tree loops around Earth in its inclined circular orbit, maintaining its altitude with puffs of waste gas.
* ViciousCycle: the Reboot.
* VirtualGhost: The limited-sentience projection of Nemoto, which leads to a WhatMeasureIsANonHuman moment.
* WeHaveReserves: The reason for which the Waganda are able to operate a nuclear fission reactor, despite their otherwise mediocre tech.
-->''They were just heaps of a radioactive material, such as uranium, into which reaction-controlling moderators, for example carbon rods, were thrust. Technical complexity only came if you cared about human safety: shields, robot devices to control the moderators, a waste-extraction process, and so forth. If you ''didn't'' care about wasting human life, a reactor could be made much more simply.''
* WhatMeasureIsANonHuman: Nemoto usually communicates with space travelers through holographic projections. One, however, is different--an advanced "limited-sentience projection", basically a copy of Nemoto's personality in a holographic "body". The characters, who have been away for subjective centuries due to relativity, have to ask what a "limited-sentience projection" is. Virtual Nemoto explains, bringing the concept into her awareness, then has just enough time to look horrified before her time expires and she evaporates into unbound light.
* WhoWantsToLiveForever: Nemoto keeps herself alive with advanced medical treatments for well over a thousand years, so she can deal with the problem of the alien Gaijin (and whoever the Gaijin are fighting). She doesn't seem to enjoy it much, and becomes extremely crotchety but she's too much of a control freak to leave things in anyone else's hands.
* {{Xenofiction}}: The short segments from the perspective of a lunar flower. The latter half of the last chapter, which is told from the POV of [[spoiler:Reid Malenfant after he gives up his humanity, might also count]].
* YouCantGoHomeAgain: For the time-shifted star travellers. While they can return to Earth if they wished, it'll be an Earth drastically changed, with their loved ones all dead, and for them home no longer exists.
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