Overview: From Eternity to Here is a survey of the thinking and research into a simple question "why is there an arrow of time?". The simple answer is "because the past has low entropy and the future has high entropy", done. Sean Carroll asks the simple question of "why does the past have low entropy?" and spends the book explain what science, both good and bad, points us to an answer. He discusses the idea of temporal chauvinism that our timeline shouldn't be privileged and that, entropy as an explanation, while powerful, has big implications into how we experience a notion of time.

Writing: While I enjoy books on Cosmology and "big physics" most are a fight with the author to figure out what they assume the reader knows. Lawrence Krauss runs into this problem and even Richard Feynmann makes the assumption that once something is explained, however elegantly, it'll never need to be revisited. Sean Carroll makes no such assumption and has a rare gift for issuing timely reminders on what he's talking about. Despite having just read some blob of text on de Sitter space, his next chapter includes a one-liner of "remember de Sitter space has a positive vacuum energy and anti de Sitter space has a negative vacuum energy". Another polite tactic is how he reminds the reader of differences between how experts and laypeople define terms. This popped up when talking about multiverse in the sci-fi sense of realities somehow separated by another dimension and multiverse in the sense of a patch of spacetime that moves together meaning stuff outside of that area will never and can never effect something inside of it.

Organization: Leonard Susskind writes such that he states his theory at the beginning and spends the rest of the book explaining it. Instead, Sean Carroll spends the first 15 chapters explaining the problems that face modern cosmology, one chapter explaining how he answers those problems, and a final one admitting his idea's shortcomings as well as suggesting the leg work required to prove his idea. Normally, the term "humble" applied to a big brain means "quiet arrogance" but not in this case. I think Carroll's genuinely of the opinion that his model is a contender and seems very excited to tell you about it.

Flow: There were a few cases where I had to page back once or twice to remember the idea of the current chapter but the pacing was acceptable except when he dove into the history of statistical mechanics which was 20 pages too long for my taste. This may be because I consider Boltzmann a personal hero but his discussion of boltzmann-lucretius space borders on droning. The first few chapters move slowly but I think this is of necessity; we're simply not used to thinking about time in a strongly analytical manner.

Rating: My five star usually means "I'd recommend it to everyone" which I'd love to grant the book but while being inviting to even the non-enthusiast, without a glossary, better organized footnotes, and a few more reminders, I think people who've not at least been exposed to some big ideas in Cosmology would find the book 400 pages of drivel. Otherwise, it's awesome.