Atomic Clocks
 Baby Collar, Dong people. China, Yunnan province, 20th century 38 x 19 cm. From the collection of Tan Tim Qing, Kunming. Photograph by D Dunlop.

We can think of atoms as little clocks having a phase-angle $\theta$ that varies with the time coordinate $t$ like

$\theta = \theta_{0} +\omega t$

where $\omega$ is the angular frequency and $\theta_{0}$ is some arbitrary initial value of the phase angle. Sub-atomic particles also clump together in bigger atomic aggregates that oscillate and jostle about in ways that are not simple. But different modes of vibration have been examined experimentally and assessed for their stability and practical application for use as clocks. Some are excellent. Atomic clocks can be used to make time measurements that are good to about one part in 1014 and they are still being improved. The current standard for a high precision laboratory clock uses atoms of caesium. For more detail, here is a link to the Wikipedia article on .
 Next step: cause and effect.

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page revision: 117, last edited: 20 Jan 2017 20:03