Manifold Time
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 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 Stephen Baxter's Manifold series.
- Absent Aliens: Despite coming to dominate the universe, humanity never found any other intelligent life.
- Abusing the Kardashev Scale For Fun and Profit: 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.
- Alternate Continuity: To the other books in the Manifold series.
- Apocalypse How: 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.
- Bizarre Baby Boom
- Child Prodigy: "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.
- Fling a Light Into the Future: Well, into the past, but close enough.
- Set Right What Once Went Wrong: The motivation of the downstreamers. In addition, 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 the Universe itself. It spawned no other intelligent life other than humanity itself, and they'll have none of 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.
- Stable Time Loop: The notes Malenfant leaves for himself 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 Aliens / Humans Are Cthulhu: 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 the gestation of a googolplex more, by sacrificing themselves and their history. Spacebattles.com seems to think they're the Ur Example of this trope.
- Time Travel: In addition to the information the downstreamers send back, Malenfant goes on a tour of the universes that existed before this one; he ends up in the distant future with the downstreamers but chooses to travel back to just before the vacuum collapse incident.
- 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.
- Zero-G Spot: It's mentioned that one spaceflight saw frequent zero-g orgies because the astronauts had no better way to pass their time.