As the title implies, the second part of the Manifold trilogy is about space. To be more exactly, about the Fermi paradox, which is rooted in the question why no aliens have yet shown up, despite the fact that there’s so much space, so many possibilities for life to arise on other worlds. Baxter doesn’t give just one, but actually two answers, a hard and a soft one (in this context it does mean there’s a way to escape the soft one, but the hard one is nearly inescapable, at least for some time).
It’s hard to explain, but the soft one reminded me of some plot elements of David Zindell’s Neverness and the hard one of some plot elements from Greg Egan’s Diaspora (something that’s happening far too often in recent times, I obviously read too much or the pattern matching part of my brain is running amok). I won’t say much more, since I don’t want to spoil too much of the plot, because discovering the ideas and concepts is most of the fun.
Despite being about space, the actual plot covers a lot more time than the plot in the first book. Manifold Space isn’t as concise in telling its story as Manifold Time was, everything is sprawled over eons. This makes it sometimes more exhausting to read and reminded me in that way a bit of Stapledon’s Last and First Men. It’s a bit like a future history of the Earth. Don’t expect a nice future with an enlightened mankind, this is after all Stephen Baxter, who doesn’t seem to have much hope in mankind in the long run.
Still, to me it was fascinating, even if it lacks character development, even more than Manifold Time. Surely, the characters in the book grow and change, but over such long time spans that it doesn’t really feel the same like watching a typical character change. It’s more like watching riverbeds change their course over eons.