This is a bit early for #ThrowbackThursday!

More seriously, if the topic is of interest to you, I recommend Tanenbaum's book on Distributed Systems. In particular, the chapter 4 explains the rationale behind vector, or logical, clocks using very down-to-earth examples. I did not realize how time synchronization could be such a pain before reading it.

More generally, Tanenbaum's books are always of really high quality. There are maybe slightly outdated, but if you are looking to learn about the fundamentals - it is a safe bet.

This paper and other interesting topics are covered in an introductory form here: http://book.mixu.net/distsys/single-page.html . There are also great references to seminal papers and other interesting research.

This very detailed discussion of clocks and synchronicity sounds oddly like the discussion of clocks in special relativity and in quantum field theory.

https://en.wikipedia.org/wiki/Time_dilation

Lamport clocks are awesome. I've used them in the past in really affective ways with data which needs to be synchronized, and you need to discover only the data updates which you are missing. Lamport breaks this down into such a simple method for tracking that in an elegant way.

Shameless self/conference plug: I'll be talking about logical clocks at Midwest.io next month.

It's a new conference as of last year, was really impressed with it. Organizers have been inspired by Alex Miller and Strange Loop.

I think it would be good if author explained why we cannot use a reliable NTP server.