Ian McDonald 
Empress of the Sun 

The airship Everness makes a Heisenberg Jump to an alternate Earth unlike any her crew has ever seen. Everett, Sen, and the crew find themselves above a plain that goes on forever in every direction without any horizon. They’ve arrived on an Alderson Disc, an astronomical megastructure of incredibly strong material reaching from the orbit of Mercury to the orbit of Jupiter.Who could have built such a thing? The Jiju, the dominant species on a plane where the dinosaurs didn’t die out. They evolved, diversified, and have a twenty-five million year technology head-start on humanity. If they ever get off their plane, and into the worlds of the Plenitude…Everness has jumped right into the midst of a faction fight between rival nations, but can anyone be safe among the warring Jiju, and what is the price of their help?The crew of the Everness is divided in a very alien world, a world fast approaching the point of apocalypse. And back in the Plenitude of Known Worlds, Charlotte Villiers gathers allies and works her way deep into the corridors of power.Praise for Empress of the Sun"YA or not, the Everness series may be the most enjoyable ongoing series that SF currently has to offer." -Locus"The marvelous Everness series takes readers to a world with highly evolved dinosaurs in this third voyage through parallel universes… Mc Donald lets his imagination run rampant without abandoning credibility, tackling real scientific concepts such as confirmation bias, a feature lacking in far too much science fiction… Endlessly fascinating and fun." -Kirkus (Starred Review)"With strong characters covering all ages and genders, fine action sequences, and enough cool SF concepts that could fill a volume twice its size, EMPRESS OF THE SUN is an excellent entry in one of my favorite SF series." -SF Signal