This book is about one of my favourite subjects - the multiverse and the ontological pickle. Our protaganist, Paul Girard, is granted the ability to traverse the mutliverse - an infinite number of universes with an infinite number of possible variations - using a yo-yo made of "strange matter". All he has to do is think of where he wants to go, spin the yo-yo and he'll be there. However, with an infinite number of possibilities there is an infinite amount of interpretation that can be applied to your wishes. Paul discovers this quite fast as he misadventures through cellular automata, meme worlds, universes ruled by chaos or morphic resonances, singularities and finally, the Omega Point. He picks up quite a few people along the way and by the end, perhaps learns something from it.
The real treat in reading this book is the sheer amount of ideas that Di Filippo pours out onto every page. Menger sponges, references to the work of Italo Calvino, group personalities, happy cats, and the biggest question humanity has ever asked - "Why is there something instead of nothing?" - are all explored and more! Di Filippo takes these concepts and molds them into entire worlds.
Science fiction can often be annoyingly unimaginative - with the whole realm of possibility to play with writers often don't think very far past their own experiences. Di Filippo turns this on it's head - his character, Paul, makes some very mundane choices with his yo-yo, but Di Filippo manages to expand each one into places that you have never even thought of.
If you love high-concept science fiction then this book is for you. It'll take you through all 10 dimensions and back again!