Quarantine is an earlyish Greg Egan book. I think. I found a terrible-condition copy at a used bookstore and I felt pretty sure I’d never seen another edition of it anywhere before, so yeah. It’s sort of a detective story/technothriller kind of thing based on quantum mechanics and the idea that every time people make choices and collapse waveforms we’re killing off whole universes. Also, at some point in the 2030s all the stars disappeared; the solar system was isolated in its own little bubble.
There was a lot of exposition and some good twists (by the end it doesn’t really feel like the book you started). Egan returned to similar themes in one of the stories in Crystal Nights, “Singleton” though I don’t think the stars being gone was a part of that. In fact that story felt like a mirror reflection of this novel.