I don’t understand quantum physics or string theory, really — I couldn’t possibly explain them to someone, anyway. But I keep trying to, and this book has probably got the closest to making me really interested in the topic. It’s easy enough to follow, and doesn’t throw maths at you without explanation, and it helps that it’s focused on one of the important more interesting factors: quantum theory and string theory could require a multiverse. Gribbin has a look at all the reasons a multiverse seems likely, including the fact that quantum computing works at all, and takes you through anthropic reasoning, etc, etc.
Overall, I still find parts of this difficult to get on with. We can’t know that we live in an average universe — even if there are an infinity of different universes, that doesn’t follow that universes which are suitable for life are more common. We could be living in a rare universe. We can’t see what the probabilities of anything are when we only have experience of one universe — nobody has ever convinced me we have the data to really judge.
This is probably going to date badly when it comes to its explanations of string theory and a theory of everything, but for someone as lacking in knowledge as me, it works.