This article, written by a scientist from NIST, reflects on the nature of time and its measurement. The author recalls how his early interest in time led him to a career in developing highly precise atomic clocks. He explains that time is measured through periodic motion, such as the oscillations of atoms, and that modern atomic clocks are so accurate they would lose only one second every 300 million years. These clocks are now based on optical transitions in atoms, which allow for even greater precision than the traditional cesium-based atomic clocks. The article also discusses how these clocks are sensitive to gravity, as predicted by Einstein’s theory of relativity, and how they could be used in the future for applications like deep-space navigation and detecting changes in Earth’s surface.
The author also explores philosophical questions about time, suggesting that time is not a dimension but a measure of motion. He argues that without motion, time cannot be measured or even exist. The article touches on the idea that the universe may have had a time dimension from the very beginning, due to the presence of motion like spin. Looking ahead, the author mentions that the definition of the second may soon be updated to reflect the performance of next-generation optical atomic clocks, which could be placed in space to avoid disturbances from Earth’s surface. This evolution in timekeeping continues to open new possibilities for scientific discovery and technological advancement.
Source: https://www.nist.gov/blogs/taking-measure/what-then-time
Keywords: atomic clocks, optical atomic clocks, timekeeping
