The title is Matter, by Iain M. Banks, and the plot involves the inhabitants of a "shell world" (artist's rendering above) ... there's been a murder in the Royal Family and surviving Prince Furbin evades the killer with his trusty servant Holst ...
There are a lot of interesting ideas in this novel:
- the idea of the Universe being a simulation, and of war being better waged as a simulation
- the Many Worlds interpretation of quantum mechanics
- The interaction between cultural less developed civilizations and the "optimi" like the Culture and peers
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