This was a confusing book, not so much because of the physics of it (which are complex) but because it seems to not be sure what kind of book it wants to be. We meet characters from the present, past, and distant future, presented out of time, telling a tale of a possible missing or maybe-it-never-existed very important book which might change the course of history. And there were a lot of homages to Golden Age scifi which were neat but felt gratuitous. If you are someone who appreciates that kind of homage, this might be more up your alley.