Pegram Lecture

In the standard picture of the history of special relativity, Einstein's reformulation of simultaneity is considered a quasi-philosophical intervention, a move made possible by his *dis*-connection from the standard physics and technology of the day. Meanwhile, Einstein's engagement at the Patent Office enters the story as a lowly day job, irrelevant to his work on relativity. I argue, on the contrary, that Einstein's patent work located him squarely in the middle of a wealth of technological developments, cultural discussions about the meaning of time, and important patents that accompanied the coordination of clocks. And Henri Poincare, far from being lost exclusively in the far reaches of abstract mathematics, was at the same time profoundly involved with the use of precision coordinated clocks for long-distance longitude determination. Indeed, at a crucial moment in the development of Poincare's own thoughts on simultaneity, he was presiding of over the Paris Bureau of Longitude. By understanding the history of coordinated clocks, Einstein's and Poincare's work in relativistic physics shines in a very different light: the "modern" of "modern physics" stood was the intersection of physics, technology, and philosophy.