Jonathan Hockey’s Reviews > Einstein's Clocks, Poincaré's Maps: Empires of Time > Status Update

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.