Quarantine — Greg Egan

It causes riots and religions. It has people dancing in the streets and leaping off skyscrapers. And it's all because of the impenetrable gray shield that slid into place around the solar system on the night of November 15, 2034.

Some see the bubble as the revenge of an insane God. Some see it as justice. Some even see it as protection. But one thing is for certain -- now there is the universe, and the earth. And never the twain shall meet.

Or so it seems. Until a bio-enhanced PI named Nick Stavrianos takes on a job for an anonymous client: find a girl named Laura who disappeared from a mental institution by the most direct possible method -- walking through the walls.