> Atomic-based Coordinated Universal Time was implemented in 1972, > superseding the astronomically determined Greenwich Mean Time. > This reminds me of a neat book I read recently "Einstein's Clocks and Poincare's Maps by Peter Galison. He places the discovery of relativity within an historical context that I had never heard about: The late 19th century international effort to define precisely and unify time for all users. Galison discusses the political struggles over how time would be unified in particular with reference to france england and the US. The need for uniform time was mostly to keep railroad schedules accurate so that trains did not collide but time precision and unification became something of a fad. Poincare was the ultimate insider heavily involved in french naitonal efforts to unify time in a way that paid due credit to his country. He was mainstay of the french rationalist tradition that had successfully instituted the uniform measures of the metric system. He had been involved in the bureau of mines. He was the french ideal of polytechnician - an engineer mentality that sought solutions to concrete problems. But of course he was also one of the greatest mathematicians physicians and philosophers science of the 19th century. He came to relativity from both a practical and theoretical position that enabled him to solve the problem but only within the context of traditional science which he did not seek to overthrow. So he kept the either and he kept the concept of an absolute time but they were without consequence. Like Einstein he dealt with and solved the problem of simultaneity by making all measurements relative to each other.
Einstein was the ultimate outsider. He was seeking to overthrow the old. But like Poincare he was encased in a culture that was obsessed with time. Einstein was a file clerk in the patent office of Bern. This is usually described as "lowly" and I had always assumed that this was a beurocratic position. Not according to Galison. The file clerks were all well trained physicists who reviewed the patents with a very critical eye. Einstein's boss taught him how to look for every assumption. Much of the work of the patent office had to do with clocks so Einstein was emmersed in time at work as well as in his thoughts. I do not do justice to the book (although he does spend more time than I needed on railway time measurement). A very neat perspective
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