Unfortunately, this book is only good in theory. By that I mean Lightman has a great idea, but the execution was flawed. The idea is that before Einstein presented his theory of relativity he was spending a lot of time thinking about Time and perhaps he even dreamed of different way time might flow or be experienced. The book presents over 30 very short explorations of different concepts time or ways in which it might exist. The first problem was that the writing was somewhat dry (perhaps this was due to a lack of dialogue as most of the descriptions of these different time worlds were primarily descriptive). The second problem was that some of the worlds explored were logically incoherent. While it might be possible to have logically incoherent worlds, the concept is so confusing that one can make little sense of what that would be, as well as why some aspects of causality and logic would be preserved while others would not.
I did enjoy some of the stories, especially the ones that were more parabolic (i.e., like a parable) and suggested that maybe we all shouldn’t run around in a hurry so much.
In summation: probably best to avoid this one and instead try to think of different ways in which time could be experienced/exist.