The European Physical Journal H

, Volume 41, Issue 1, pp 1–67

The history of time and frequency from antiquity to the present day


DOI: 10.1140/epjh/e2016-70004-3

Cite this article as:
Levine, J. EPJ H (2016) 41: 1. doi:10.1140/epjh/e2016-70004-3


I will discuss the evolution of the definitions of time, time interval, and frequency from antiquity to the present day. The earliest definitions of these parameters were based on a time interval defined by widely observed apparent astronomical phenomena, so that techniques of time distribution were not necessary. With this definition, both time, as measured by clocks, and frequency, as realized by some device, were derived quantities. On the other hand, the fundamental parameter today is a frequency based on the properties of atoms, so that the situation is reversed and time and time interval are now derived quantities. I will discuss the evolution of this transition and its consequences. In addition, the international standards of both time and frequency are currently realized by combining the data from a large number of devices located at many different laboratories, and this combination depends on (and is often limited by) measurements of the times of clocks located at widely-separated laboratories. I will discuss how these measurements are performed and how the techniques have evolved over time.

Copyright information

© EDP Sciences and Springer-Verlag Berlin Heidelberg 2016

Authors and Affiliations

  1. 1.Time and Frequency Division and JILA, National Institute of Standards and Technology and the University of ColoradoBoulderUSA

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