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The Invention of Time: Why The Day Has Twenty-Four Hours
On the origins of calendars and clocks
This story was originally published by The Quantum Cat, a regular newsletter covering space and science. Get it for free by signing up today!
Year 169, month XII, night of the sixth,
beginning of the night,
the Moon one cubit to the west of Alnath.
In the morning, the child was born.
~ Babylonian Horoscope
In Colorado, amid the foothills of the Rocky Mountains, we have built a clock so accurate it would not have erred by a single second in all the years since the Big Bang.
Such precise counting of time is possible only at the frontiers of modern physics. The clock measures the steady beat of electrons vibrating in atoms; a feat that required not only the use of vacuums and lattices of lasers, but also the careful elimination of every possible disturbance.
To do this, the builders of the clock isolated it from the outside world. It sits enclosed in a temperature controlled box, inside a vacuum. The mirrors in its optical systems are shielded with copper to reduce stray electrical fields, and its lasers are run at as low a power as possible.
