Everyday Time and Atomic Time: Part 3

NIST/JILA Fellow Judah Levine discusses the history of time and frequency measurements.

View as a Web Page Taking Measure Blog Everyday Time and Atomic Time: Part 3 By Judah Levine, a physicist at NIST and a professor at the University of Colorado Boulder In the previous essay, I introduced the ideas that frequency and time interval are closely related concepts, and that the time at any instant is a count of the number of basic time intervals (such as the second) that have elapsed since some origin. These relationships became very significant because of two developments in the late 19th and early 20th centuries. Read More IN CASE YOU MISSED IT Everyday Time and Atomic Time: Part 1 March 31, 2021 Coordinated Universal Time (UTC) is the legal time in most countries. Currently, UTC is based on data from an international ensemble of atomic clocks combined with astronomical observations on the rotation rate of Earth. The UTC time scale is kept within 1 second of astronomical time (which I will define later) by the occasional addition of "leap seconds."  Read More Everyday Time and Atomic Time: Part 2 April 7, 2021 Frequency was originally considered to be the province of musicians. The pitches or frequencies of the notes in a musical scale are defined by ratios — octaves, for example, where the frequency of the higher note is twice the frequency of the lower one. The 12 notes between octaves in Western music are also defined by ratios — in principle the ratios of small integers, because notes that have this relationship are generally regarded as pleasing when sounded together and because these relationships arise naturally in the resonant frequencies of vibrating strings and pipes. Read More

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