Humanity spread throughout the universe, but never found other intelligent life. Far into the future, matter having long since decayed away, the last descendants of humanity have survived by embedding themselves into a [[AscendToAHigherPlaneOfExistence lossless computing substrate]]. They can theoretically survive indefinitely, but since there will never be new input, their thoughts are doomed to eventually begin repeating. A faction decides this was not meant to be and reaches back to the distant past...

The year is 2010. More than a century of ecological damage, industrial and technological expansion, and unchecked population growth has left the Earth on the brink of devastation. Strange, hyper-intelligent children are being born all over the globe. As the world's governments turn inward, Reid Malenfant campaigns for the exploration and colonization of space. Battling national sabotage and international outcry, as apocalyptic riots sweep the globe, he builds a spacecraft and launches it into deep space.

Part of StephenBaxter's ''Manifold'' series.
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!!This book provides examples of:
* AbsentAliens: Despite coming to dominate the universe, humanity never found any other intelligent life.
* AbusingTheKardashevScaleForFunAndProfit: In the distant future, descendants of humanity maintain vast Dyson nets around the supermassive black hole remnants of galaxies until they evaporate via Hawking radiation, accessing the power equivalent of multiple galaxies. And in the present, once the Blue children start tapping into this knowledge, things get a little crazy.
* AlternateContinuity: To the other books in the ''Manifold'' series. The story is notable for [[spoiler: likely making the other ''Manifold'' continuities ''possible'' by spawning a massive multiverse.]]
* ApocalypseHow: [[spoiler:Class X-4: The Blue children instigate a vacuum collapse incident, causing the fabric of space to collapse into a new energy state within a bubble expanding at lightspeed.]]
* ArcWords: "Watch the Moon, Malenfant".
* AscendToAHigherPlaneOfExistence: What the Downstreamers did to escape the Heat Death. However, this still isn't enough as shown in Manifold: Origin, they escape their inevitable fate by reaching [[UpToEleven an even higher level of existence]].
* BeamSpam: One of the tactics tried against the children's bubble. [[spoiler: Didn't work]].
* BiggerOnTheInside: The Blue children's space-time bubble. In fact, it's actually ''infinitely'' big on the inside, despite being only a few meters across on the outside.
* BizarreBabyBoom
* BlueAndOrangeMorality: Despite being descended from humans, the Downstreamers are described this way, the only real thing they have in common with modern humans is the instinct to survive.
* ChildProdigy: "Prodigy" doesn't even ''begin'' to describe the Blues, who are under the influence of a civilization from the end of the universe. Humanity as a whole is considerably freaked out by them.
* CoolGate: The Downstreamer portals.
* DeityOfHumanOrigin: Despite Michael's claim that the Downstreamers are not gods, they certainly qualify for this.
* DetonationMoon: Happens as a prelude to the vacuum collapse.
* DeusEstMachina: The Downstreamer neutrino computer, capable of storing all of the information that could ever possibly exist in the universe.
* FlingALightIntoTheFuture: Well, into the ''past'', but close enough.
* GooGooGodlike: The Blue children, due to their intelligence.
* GoMadFromTheRevelation: Lampshaded by several of the characters, as they fear this would happen to them if they were a bit smarter and able to actually understand the implications of the things they were learning.
* HumansAreCthulhu: Posthumans from the far future, that is.
* MadeOfIndestructium: The children's bubble as well as the ring portal.
* TheMultiverse: Referred to as [[TitleDrop The Manifold]].
* NuclearOption: The last resort against the Blue children. [[spoiler: It doesn't work]].
* PortalNetwork: Implied, although it could possibly be the same one, persisting throughout multiple universes and far into the future. Towards the end of the book, however, we do see an infinite tunnel of them.
* Precursors: The entire point of the book is how humans become this.
* ReedRichardsIsUseless: Played with. The Blue children offer humanity many advances, but humanity is too scared of them (combined with the Carter prediction) and decide to attack them instead. Even 200 years later on, they're still far behind what the children could come up with.
* ScienceMarchesOn: At one point, phenomenon known as Centauro events were mentioned, which in the book were suggested to be due to exploding chunks of quark matter in the atmosphere. They have since been proven to be simple misreadings of instruments.
* SetRightWhatOnceWentWrong: The motivation of the Downstreamers. In addition, [[spoiler:Malenfant gives up his chance at a life in the far future to stop someone from ever going on the journey with him (during which she died)]].
** To elaborate: what "went wrong" is [[spoiler: the ''Universe itself''. It spawned no other intelligent life other than humanity itself, and the Downstreamers will have ''[[ScrewTheRulesIHaveSupernaturalPowers none]] [[ScrewTheRulesImakeThem of]] [[ScrewTheRulesImDoingWhatsRight it]]''. They reconfigure its vacuum state into one where black holes are much more frequently formed. Since every black hole singularity is a "cosmic egg" for a new Big Bang, they essentially germinate countless new universes by sacrificing one (along with themselves). They reason that intelligent life ''just has'' to evolve in these new circumstances]].
* StableTimeLoop: The notes Malenfant leaves for himself [[spoiler:inside the simulation in the distant future]]. Also, the strange matter nugget the Blues send back in time. But for the rest, the Downstreamers really are changing the past.
* {{Sufficiently Advanced Alien}}s / HumansAreCthulhu: The Downstreamers are essentially ''gods''. End of story. They can influence events in the past and have more energy at their disposal than entire galaxies, can travel to other universes, ''create'' other universes, and their plan is essentially [[spoiler: the gestation of a googolplex more, by sacrificing themselves and their history]]. {{Spacebattles}} seems to think they're the UrExample of this trope, though they seem to have drawn considerable inspiration from late-nineties depictions of the [[DoctorWho Time Lords]].
* SuperIntelligence: The Blue children, as well as the later generations of squid, and of course the Downstreamers themselves.
* TimeAbyss: The Downstreamers are an extreme example, having lived for over 10^117 years (that's one billion trillion trillion trillion trillion trillion trillion trillion trillion trillion years).
* TimeTravel: In addition to the information the Downstreamers send back, Malenfant goes on a tour of the universes that existed before this one; [[spoiler:he ends up in the distant future with the Downstreamers but chooses to travel back to just before the vacuum collapse incident]].
* TimeTravelTenseTrouble: The Blue children construct their own language which specifically accounts for this.
* [[TouchedByVorlons Touched by Downstreamers]]: Malenfant and Michael towards the end of the book.
* TwentyMinutesIntoTheFuture: The 2010 Earth, which contains things such as commonly available self-driving cars, foldable, clothlike computers (softscreens) and AI therapists. Keep in mind this book was written in 2000.
* Tykebomb: The Blue children.
* VirtualGhost: Malenfant at first thinks he has become one of these in the Downstreamer substrate, before Michael explains that it really is his original consciousness.
* WhoWantsToLiveForever: The Downstreamers do, at least initially, until they realize their ultimate fate is to be locked in a sterile, never-changing cosmos. So they go back and fix things. It's implied they survived in some form (expanded in Manifold: Origin).
* WouldHurtAChild: Wayne Dupree, and later the US government, who even resort to nuclear weapons.
* {{Xenofiction}}: A major subplot involves Malenfant using squid, modified to be more intelligent, as a space exploration force. This is told from the squids' perspective.
* ZeroGSpot: It's mentioned that one spaceflight saw frequent zero-g orgies because the astronauts had no better way to pass their time. Malenfant and Emma also took part in this during their trip to Cruithne.
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