Schild’s Ladder (2001)

Backcover Synopsis: Cass has stumbled on an entirely different kind of physics, and she has traveled to a remote experimental facility in the hope of bringing this tantalizing alternative to life. Cass’s experiment is wildly successful: the novo-vacuum is more stable than the ordinary vacuum around it, and a region in which the new physics holds sway proceeds to expand at half the speed of light.

Six hundred years later, more than two thousand inhabited systems have been lost to the novo-vacuum. People have come from throughout inhabited space: most are Preservationists, hunting for a way to stop the novo-vacuum before all inhabited space is consumed, but a few believe that the challenge of adapting to survive on the far side of the border would reinvigorate a civilization that has grown stale and insular…

This book was Egan’s proof that he was back to form after Teranesia. It shows all his strengths, inventive ideas, speculative physics, questions about philosophy and morality, and his will to go further than anybody else. Unlike others authors, Egan makes me at times think that what he envisions is really how the far future might look like, not the small details, but rather the overall feeling of his future. The way how his future people think about our time, how they interact with each other.

Egan’s novel is also one of the few SF books that has a STL civilization on a galactic scale. If there’s a weakness, it’s that the reader has to be interested in exploring strange places, the whole third part of the book until the end is about that, and if you read books mostly for characters, you’ll find yourself lost.