"Ellis Rogers is an ordinary man who is about to embark upon an extraordinary journey. All his life he has played it safe and done the right thing, but when diagnosed with a terminal illness, he's willing to take an insane gamble. He's built a time machine in his garage, and if it works, he'll face a world that challenges his understanding of what it means to be human, what it takes to love, and the cost of paradise. He could find more than the cure for his illness; he might what everyone has been searching for since time began...but only if he can survive Hollow World"--back cover.
"Science fiction masters Larry Niven (Ringworld) and Gregory Benford (Timescape) continue the thrilling adventure of a human expedition to another star system that is jeopardized by an encounter with an astonishingly immense artifact in interstellar space: a bowl-shaped structure cupping a star, with a habitable area equivalent to many millions of Earths. And which, tantalizingly, is on a direct path heading toward the same system the human ship is to colonize. Investigating the Bowl, or Shipstar, the human explorers are separated--one group captured by the gigantic structure's alien inhabitants, the other pursued across its strange and dangerous landscape--while the mystery of the Shipstar's origins and purpose propel the human voyagers toward discoveries that transform their understanding of their place in the universe"-- Provided by publisher.