Quarantine by Greg Egan

Mindblowing Hard Science Fiction. A detective/spy novel in a world where humans use nanomachines to control their moods, improve their attention, access and process information, and many other things. At the core of the mystery there is a twist on actual quantum mechanics theories which try to explain the nature of reality. I think they are related to the principle of "complementarity", part of the Copenhagen Interpretation of quantum theory which states that the "quantum world is both wave - and particle-like, its the act of measurement that causes it to show one face or another. " (New Scientist, Essential Guide 1&5). Greg Egan adapts the concept of measurement making it an inherent human ability, something that we ourselves do unwittingly to create and recreate our reality. And then something happens when someone discovers how to not do that. The novel can be hard to read at points. There is hard science everywhere, explaining particles, waves, smear, probabilities, etc. but the actual plot is really interesting and worth the effort.