When you use the GPS in your phone or car, your device receives wireless signals from at least four of the twenty-four satellites in the global positioning system that are orbiting about twelve thousand miles overhead. Each satellite carries four atomic clocks that are synchronized to within a billionth of a second of one another. The various satellites visible to your receiver send it a continuous stream of signals, each of which is time-stamped to the nanosecond. That’s where the atomic clocks come in. Their tremendous temporal precision gets converted into the tremendous spatial precision
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