This is a book about black holes - and there are two ways to look at these amazing phenomena. One is to meander about in endless speculation concerning firewalls and holographic universes and the like, where there is no basis in observation, only mathematical magic. This, for me, is often closer to science fiction than science fact. The alternative, which is what Marcus Chown does so well here (apart from a single chapter), is to explore the aspects of theory that have observational evidence to back them up - and he does it wonderfully. I'm reminded in a way of the play The Audience which was the predecessor to The Crown . In the play, we see a series of moments in history when Queen Elizabeth II is meeting with her prime ministers, giving a view of what was happening in life and politics at that point in time. Here, Chown takes us to visit various breakthroughs over the last 100 or so years when a step was made in the understanding of black holes. The first few are around the ba...