This is hard science fiction right on the cutting edge of physics, cosmogeny and cosmology just like I like it. The plot concerns an interstellar war with an unfathomable species and presents some interesting twists and turns because both sides can accomplish time travel and thereby can receive actionable information from the future. Just give some thought to how that would effect strategy and tactics. To me, though, the most interesting premise of the book is what is actually something of a subplot. It is a subplot told in a series of flashbacks and these flashbacks flash back about as far as is conceivable. It turns out that an entire civilization rises, flourishes and begins to die all in the first nanosecond after the big bang. The beings that make up this civilization almost go into despair as baryonic matter begins to coalesce because that means the end to all of them. However, they get to work trying to survive the next stage in cosmological evolution. They have a certain amount of success too, but they would never have succeeded without primordial black holes. That is closely related to a statement in the book that says that the universe teems with life, even in the black holes and even in the singularity itself. To me this is fascinating stuff.