I'm a proper nerd when it comes to sci-fi - I'll take obscure and esoteric theories over plodding character development every time. Time, therefore, was very appealing.
A strange artifact is discovered on an asteroid near Earth, and is found by a remote probe to be a portal that allows jumps of billions of years into the future. Soon after, a kind of super-intelligence begins to manifest itself in a handful of children, who proceed to make astonishing scientific breakthroughs in the field of energy production. The two apparently unrelated stories close in on each other at the climax (far too mild a word for it).
It does take a while to get going, with a lot of the first half being something of a cookie-cutter will they/won't they space launch saga, but there are sprinklings of some truly visionary science (particularly the breathtaking sequence where the probe is repeatedly pushed into the distant future - worth getting from the library on its own). The rapidly switching point of view character took me some getting used to, but it does offer a more rounded insight into the goings on. And the ENDING... ye gods, Baxter went all-out!
So good was this book that it induced me to read Flood; if I'd read Flood first, though...