Status Updates From Einstein's Clocks, Poincaré...

this radical upheaval in the conception of time lay an
extraordinary yet easily stated idea that has remained dead-center in physics, philosophy, and technology ever since: To talk about time, about simultaneity at a distance, you have to synchronize your clocks. And if you want to synchronize two clocks, you have to start with one, flash a signal to the other, and adjust for the time that the flash takes to arrive.

Fascinating, especially on the social, cultural, political as well as scientific environment that Poincaré and Einstein operated in: The importance of the work on longitude for Poincaré! The importance to Einstein of the patent work in Bern!
I suspect I'll wind up purchasing a copy!