Our New Atomic Clock Is So Precise That We Need a Better Understanding of Gravity To Use It
Our measurements of gravity are not good enough for NIST's new atomic clock.
By Avery Thompson
Nov 30, 2018
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National Institute of Standards and Technology
The scientists at the National Institute of Standards and Measurement have one big job: to measure things as accurately as possible. To do that, they build a lot of big and complicated machines, including precise tape measures and absolutely gigantic scales.
For the past few years, NIST has been building the world’s most accurate clock, and new research shows it’s actually too precise. How so? It turns out our understanding of the Earth’s gravity is not good enough to take full advantage of the clock.
NIST’s clock doesn’t use gears or springs or even quartz crystals like what's inside a modern wristwatch. Their atomic clock, which occupies an entire table, works by hitting atoms with microwave radiation, which causes electrons inside those atoms to oscillate at a specific frequency.
https://www.popularmechanics.com/science/a25362045/nist-atomic-clock-gravity/