The Universal Timekeepers started out a bit rocky for me, with the opening segment feeling somewhat chaotic and disconnected, with some abrupt shifts. But after that relatively brief section, the book slowed down and smoothed out. The early sections deal more generally with the chemistry of the elements, their place on the Periodic Table, the types of bonds, differences in states, and so forth. It’s a refresher for your high school and/or basic chem classes; honestly I’m not sure it was fully necessary for what follows, but I never mind having the basics reimpressed on me. Where the book really took off for me was when moved beyond the foundational aspects and into the application of using the elements and their isotopes for dating. Here we get a number of specifics cases within several different areas of exploration, including but not limited to confirming whether works of art are real or forgeries, dating cave wall art, ascertaining whether homo sapiens or one of our now-extinct cousins created art, determining the global temperature over centuries, thousands of years, and even millions of years, piecing out the atmospheric makeup of Earth at various stages, and more, closing with more astrophysics than Earth-based information. It’s mostly all explained clearly and in easy-to-follow fashion, though it does get densely detailed in spots and there are a number of equations, but these are presented in such a manner that if you don’t really need to know the precision of which isotope of nitrogen has this effect and which other isotope of nitrogen has the effect, and just want to understand the larger point being described, that’s easy to do. There’s also a very useful glossary, and I’d also encourage readers to not skip the notes. Recommended

This book describes the workings of several dating technologies, like carbon dating, that utilise the atomic properties of materials to decipher the age and other details of an event. Though the subject matter is very technical and requires a basic understanding of chemistry, physics, and a bit of biology to fully comprehend its nitty-gritty, Helfand makes sure that the layman reader is not too confused or bogged down while reading the book. His description is elementary enough to sustain the reader's interest, though he never succumbs to the temptation to dump it down to a level that trivialises its implications.

This book was adapted from a course that the author taught for non-science students for many years. That course seems like it would be amazing and interesting. Unfortunately, distilling a ton of interdisciplinary fields into one survey course/book made all the subjects go too fast. As someone who has read a lot of pop science books about cosmology and is studying paleontology and archaeology, the last two-thirds of the book didn't expand my knowledge or think about the things that I already knew differently. The art history sections were the highlight for me - worth reading but probably not worth spending your money. Unless of course you're thinking about teaching a college course on different dating techniques across different fields, in which case this book could be your bible.

Bottom line up front: too much chemistry, not enough history.

I enjoyed the book OK, but the editor needed a heavier hand. It start with a long recap of all the high school chemistry you forget, so it takes a long time to get to the interesting parts about all the ways history can be determined, forgeries detected, etc. Authors don't always realize that what they think is their second chapter is actually their first. Start with something interesting to pull us in, then give us some background. In this case, the background would've been more effective if it had been spread out between the historical anecdotes. Unfortunately, those are outweight by the chemistry lesson, no matter how you arrange the book. We needed more history and just a little less chemistry.

There's a long section near the end that spends a lot of time on the history of the solar system and the universe,. It's interesting, of course, but it ends up seeming like it's the real focus of the book. Was that the intent? I expected more about forgery detection and human history, so maybe it was a matter of managing my expectations going in.

It's a decent read, skim through the chemistry if you didn't forget as much as the author thinks you did. He clearly loves the subject and is very knowledgeable. Be ready for unexpected balance of chemistry lessons vs. applications of those lessons, and if you're into astrophycis, you'll close strong. Worth a read by the right person.