Brian Greene's The Hidden Reality is an entertaining look at the physics behind various possible conceptual parallel universes. I listened to it as an audiobook and Greene does the narration himself. His voice doesn't have the sonorous quality of say, a Carl Sagan, but it's not annoying either. There's no brand new material in the book but he nicely summarizes some of the current developments in string theory and cosmology. I particularly enjoyed the chapter on Nick Bostrom's work and the possibility/probability that we are all living in a sim universe. I also liked the chapter on the holographic universe but after listening to it twice I can't actually say that I understood it. ...
The book makes me think it likely that there are parallel universes in space as well as time and that we are living in what can only be called a multiverse (hideous word). It's the stuff of science fiction of course from Iain Banks to Philip Pullman, but Greene is pretty convincing and I for one don't have the math to contradict him.
