This is a fantastic book, and makes me wish I had become an astrophysicist. I've read a handful of books on the subject of cosmology and physics but where those have fallen short, Professor Thorne has achieved excellence. Other books present current theories (of the author usually) without much substantiation (not quite as fact though), which is understandable due to the typically advanced and/or esoteric mathematical underpinnings. Thorne overcomes this without beating the reader to death with equations by eloquently explaining the reasoning behind the theory, including what problem it was trying to solve, what alternatives there might have been, or what objections were raised. While he does this, he's also overcoming another shortcoming in this genre, dryness, by including human characters: the physicists who worked alone, together, or in opposition to others to unlock the secrets of the Universe. I especially found the passages about Soviet physicists interesting, how the politics of the Cold War kept otherwise cooperative thinkers apart, and how the nuclear arms race both hindered and helped astrophysics research. This is one small example of the connections Thorne shows between his field and others.

Overall this is an outstanding work of science literature, even though it is 20 years old. Fans of Interstellar are probably already aware of Professor Thorne's involvement. In this book, especially the short story prologue, we can get a glimpse of the singularity from which that film sprung.