The Manifold is an infinite sheaf of alternative universes which Baxter explores in terms of Fermi's Paradox. There's no reason why humanity should be unique; logically there should be alien races, some long enough established to have made their mark on the galaxy; where are they?
Book one, Time, offered a vision of lonely humanity extending to the far end of eternity and finally rebooting a "better" universe. Space showed the consequences of teeming interstellar life, a cruel struggle for resources, punctuated by galactic-sized extinction events. Now Origin confronts the whole Manifold and its and humanity's manipulation by enigmatic "Old Ones".
Astronaut Reid Malenfant (versions of whom starred in Time and Space) again encounters advanced technology as a huge, glowing blue circle--a portal to and from the Red Moon that wanders between universes and has just replaced our own moon. It's habitable and populated by an extraordinary medley from all stages of human evolution, scooped up from different Earths. There's much conflict with primitives leading nasty, brutish and short lives... plus super-evolved humans who debate whether we are truly sentient.
At its core the Red Moon contains the failing World Engine which flips between universes. Also down there is the secret history of this multi-verse, right back to the cataclysmic branch-point from which the Manifold flowered. Who are the Old Ones? "They made the manifold"--but were maybe not so different from us and rash, quixotic Malenfant after all. Highly superior SF, guaranteed to jolt one's sense of wonder. --David Langford
‘Baxter is taking basic sf ideas and rebuilding them based on current science, technology and politics – a tried and true method sor sf writers but no less effective for that. Baxter apparently has the ambition and the energy to reinvigorate hard sf all by himself’
Locus on SPACE
‘Like all good sf, SPACE provokes questions. What kind of species are we?… the other reason SPACE works well is that Baxter is a good writer… his format and style are assured and keep you happily suspended and engrossed. Right up to the satisfyingly vertiginous climax… Malenfant is one of sf’s more memorable characters’
SFX on SPACE
‘Pacy, visionary, extravagantly imagined, Time places Baxter firmly in the tradition of Arthur C. Clarke and Isaac Asimov. How reassuring to know that while so many authors are lying in the gutter of the information superhighway, someone at least is still looking at the stars’
‘Time is a big ambitious book… science fiction at its best’