Like many in the community of theoretical physicists, Professor Hawking is after the Grail of science, the theory of everything that lies at the heart of the cosmos. He involves us in the attempts at uncovering its secrets, from supergravity to supersymmetry, from quantum theory to M-theory, from holography to duality, and now, at the very frontiers of science, superstring theory and p-branes. He shares his eagerness to "combine Einstein's general theory of relativity and Richard Feynman's idea of multiple histories into a complete unified theory that will describe everything that happens in the universe." With characteristic exuberance, Hawking invites us to be fellow travelers on this extraordinary voyage through spacetime.
Hawking seems to cover the same topics as are covered in the other book, just in a different order. It did seem as though the material was clearer this time, but whether that was due to the organization of the book or to the fact that maybe some of the information is finally sinking in on a second listen, I’m not sure. There are a few concepts I think I really understand now (for example, the Doppler effect, although that could have been demonstrated very effectively with an audio/video clip of a passing train). Once again, I had to check out the book to clarify some concepts with the illustrations.
On the plus side, Hawking is humorous and drolly dry at times, especially with his references to Star Trek (and his appearances playing poker with Data, Einstein, and Newton on "The Next Generation") and quotes from Shakespeare. However, I think two trials of Hawking in audiobook are plenty, and I won’t be buying or listening to any more.
Now, ten years later, having spent five of those years studying physics at university level, I can't find much enjoyment in this book. Admittedly, it could be a question of my taste changing while growing up - but I still enjoy A Brief History of Time.
Although there were many new tidbits for me (I'm by no means an astrophysicist) and I enjoyed reading the book, the sense of wonder was not there. The "plot" of the book was hard to follow since the book wasn't as well structured as ABHoT. Also, I have a feeling that if I had read this book back when I was 16, I might not have understood very much of it, so I'm not sure that this book is as suitable to someone who has never studied physics.
All in all, a good book if you enjoy physics without the equations every once in a while, but not something I would recommend as a must read for a beginner.
In a way, this one gave me some of what I'd been hoping for from The Grand Design, as it touches a little more on topics such as M-theory, which I am very, very fuzzy on and quite interested in learning more about, instead of concentrating mainly on the basic concepts of modern physics. So I found parts of it interesting and reasonably rewarding. On the other hand, I do think I can make some of the same complaints about it as I did about The Grand Design, namely that it's often rather too abstruse and lacking in explanatory background to make sense to the complete layman, but also frequently lacks the technical detail that might help make it more understandable to, say, someone with a decent but slightly rusty undergraduate-level background in physics and astrophysics like yours truly. Admittedly, this is a problem any popularizer is going to run into when dealing with a field like this in which it's essentially impossible to grasp certain ideas without an understanding of advanced mathematics, but I know I've seen other writers do it somewhat better.
At least the illustrations make the book very attractive, and, unlike those in The Grand Design, they tend to actually be relevant and sometimes even useful, if also a little distracting.
The reason the sky is dark at night is because not all of the light from the stars in the galaxy have reached us. This tells us that the universe must have been created at some finite point some time ago. Hawking details his own contributions to showing that the Big Bang happened. He discusses how it does no good to talk about what happened before time, which would require imaginary time. But Hawking believes scientists have a duty to investigate what happened before the Big Bang and what caused it. He has no patience for people like Carl Sagan who just weren't interested. Hawking explains Richard Feynman's concept of multiple histories. The concept of multiple histories still doesn't explain the cause of the big bang. While the crude form of the anthropic principle says the universe exists the way it is because we are here to see it, we can merge the principle with that of Feynman's multiple histories and supposedly explain why the universe is as we know it.
Determinism is obviously an issue in quantum physics. I would say that Hawking does not explain the multiple dimensions of M-theory very well; I would say he does a better job of that in The Grand Design (2010). To appeal to the sci-fi reader, Hawking has a rabbit rail on time travel. He explains how mathematically time travel is likely impossible, and would take an advanced civilization to figure out a way to do it without getting destroyed by radiation. He also has an odd divergence on human evolution and genetic engineering. While DNA doesn't seem to be evolving with new information, we're finding ways to engineer ourselves such that the human race will look dramatically different 400 years from now. We will have to do so to travel to the stars. This odd divergence on genetics is way outside his expertise and does not fit well in the book.
Hawking concludes with talk of a brane universe, and whether our universe is just a projected hologram. All of this is theoretical, which is a major problem for physicists. The scientific method, which Hawking holds favorably in The Grand Design, requires hypothesis testing. But Hawking ends the book by remarking that a particle collider larger than the universe would be required to test some of these theories. For more on these problems, and a large criticism of Hawking I plan to read Lee Smolin's The Trouble with Physics.
In all, good and accessible. 3.5 stars