““And everything we know about time, everything we can know about time, comes from the study of clocks. Time, Clocks and Relativity There are many popular books attempting to explain Relativity. In general, they take the same approach that we do with university undergraduates, revisiting the angst of physicists in the late 19th century as they struggled with the idea that the speed of light would remain constant even for a moving observer. Stripped of the math, for the benefit of the lay reader, the arguments become rather hollow. Instead, we will look at relativity as it is today: the practical engineering of transferring time signals from clocks on the lab bench, to clocks in GPS satellites and spacecraft””
