Anathem by Neal Stephenson. One of my favorite SciFi books ever, period. It's not for everyone, it's quite deep on philosophical concepts and it's in the dialogues between the protagonists where most of the "action" happens, at least in the first half of the book. Highly intellectual, salted with some classic coming-of-age concepts and set in a world where the scientific method and rules for rational thought have had centuries to mature. Science is practiced mostly in secluded "monasteries " by people living in ascetic monk/nun-like lifestyles, segregated from a cyberpunk-esque outside world. Speaking of cyberpunk, if you haven't read "Snow Crash" by Stephenson yet, do so now. It is a really short book and absolutely essential literature background as any self-respecting nerd. The plot is insane, amazing action scenes interspersed with some really interesting intellectual concepts, plot twists and totally crazy yet somehow plausible world building. Oh and the book singlehandedly inspired the later creators of "Google Earth" and those of "Second Life" and it anticipated both those things back in 1992 where most other SciFi authors hadn't even heard of the Internet yet or thought it just a fad.