How Long is A Second? Knowledge Cards

How Long is A Second? Knowledge Cards

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Clocks connect us to our universe. From the upright stick whose shadow traced the hours in the Stone Age to the pendulum inspired by Galileo's swinging chandelier, the tools we first used to slice up a day also measured the motion of the Earth; more recently, the task of measuring time has been assigned to atoms, resulting in clocks accurate to within one second in eighty million years.

The cards in this deck examine some of the challenges involved in timekeeping, from engineering the revolutionary technology of wristwatches to coordinating clocks around the world, as well as looking back to ancient stone calendars and mechanical clocks that burned incense or dripped water.