Scientific treatise (with charts and diagrams) melds with character study and social commentary in Hugo-winner Egan's stand-alone steampunk SF novel. On a faraway world with technology and culture roughly analogous to those of our Victorian era, the female polymorph Yalda studies the properties of light and discovers a celestial object that seems certain to strike her planet. A society that harshly subjugates women (easy when childbirth inevitably kills the mother) works against her as she tries to build and launch a rocket that will take her people to safety. Difficult, dense scientific conjecturing makes this a nearly impenetrable read for those lacking physics degrees or superior spatial thinking, but the societal analogy, totally alien culture, and intriguing characters are potent reasons to power through. (Aug.)
The arrival of a prolonged meteor shower spells danger for Yalda's world, part of a universe in which time and space are not differentiated and light has no universal speed. Yalda and others who share her view of impending doom conceive a plan to launch a rocket that moves at hyperspeed, fast enough to cancel the effects of time on its voyage and buy time for scientists to discover how to save their world. Egan introduces a fascinating alien species that reproduces through the division (and death) of the mother into two sets of twins. The struggle of the planet's females to make sense of a life cut short by the act of giving birth weighs heavily on the mind of the story's central character, yet the discovery of new physics takes precedence over everything else. The characters are fully realized individuals who, though they bear no resemblance to humans, reflect on their place in the universe and the meaning of their lives. VERDICT This trilogy launch by the author of Zendegi and Incandescence is an intellectually stimulating tale (complete with diagrams illustrating an alternate physics) that will appeal to fans of hard science in their sf as well as to Egan's followers and admirers of Larry Niven and John Scalzi.