Greg Egan is the Martin Gardner of science fiction storytelling, weaving mathematical and physical puzzles into entertaining howdunnits about encounters with novel forms of sentience, usually at vastly smaller scales than ours. Many of his stories, like Incandescence, are set in a post-human galaxy-spanning culture, the Amalgam, based on the idea of consciousness as an algorithm that can run on different hardware as it suits - so interstellar travel, for instance, is a simple matter of flinging your mental template (or a copy of your mind) as data to a far off receiving station where you can be re-embodied or just incorporated into any computational substrate that will let your unique OS run.
At his best (e.g. Schild's Ladder) the reader is often gripped by a plot involving a race against time to comprehend new forms of intelligent life that might be threatening the old through some inadvertent side-effect of their expansionism into the Amalgam's reality-space. At the same time, Egan has an amazing gift for explaining, Flatland fashion, the physics of extreme environments; working through the consequences of Planck scale realities or multi-dimensional spaces to render them almost as intuitively as we accept the everyday physics of our world.
In Incandescence, the story alternates between two investigators from the Amalgam trying to comprehend the possibly tragic fate of just such a new form of sentience and the struggle of that life form to comprehend its environment before the volatile conditions which exist in the star-packed inner core of our galaxy makes them extinct.
Although entertaining - I found myself rooting for the little sextupeds turning themselves on to the joys of physics - perhaps the maths that Egan describes here -- of huge gravitational forces and plasma dynamics -- aren't quite as exotic as in his other books. One half of the chapters are really just an exercise in the re-invention of Newton's Laws, Keplerian orbits, the differential calculus, special and general relativity and so on, familiar I suspect to any reader with a New Scientist-level physics education. Something is missing from the story as pure sci-fi because the reader isn't so much being stimulated by new physical concepts as being forced to try to remember the way, say, physicists solved the problem of orbits or the curvature of spacetime, etc.
It was tempting to see this tale as an allegory of a civilization at threat of extinction from vast environmental change (i.e. global warming) but even that is spoiled by a deus ex machina -- Egan's six-footed Einstein's are universally prone to collaboration and consensus! The only threat they face is lack of time, not their own foibles as a species.
Still, Incandescence is a wonderful antidote to space opera and many of Egan's descriptions of physics experiments inside extreme gravity wells are ingenious and elegant. Buy this book if you enjoy mental exercise and mathematical puzzles, but only if your scientific education is pre-college. Otherwise it might just feel like a history lesson.