
There are hundreds of atomic clocks in orbit right now, perched on satellites all over Earth. We depend on them for GPS location, Internet timing, stock trading ... and space navigation?Today on the show, hosts Emily Kwong and Regina G. Barber learn how to build a better clock. In order to do that, they ask: How do atomic clocks really work, anyway? What makes a clock precise? And how could that process be improved for even greater accuracy?For more about Holly's Optical Atomic Strontium Ion Clock, check out the OASIC project on NASA's website.For more about the Longitude Problem, check out Dava Sobel's book, Longitude. Listen to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave.Have questions or story ideas? Let us know by emailing [email protected]!Learn more about sponsor message choices: podcastchoices.com/adchoicesNPR Privacy Policy
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Hey, everyone. Regina Barber here with Emily Kwong and a story about time. Yes.
A tale about how time tells us our place in the world. So, Gina, are you familiar with longitude?
Yeah. So longitude is like the east-west position on Earth. It's relative to the Prime Meridian in Greenwich, England, right?
Yeah. The longitude there is zero degrees and extends by 180 degrees westward and 180 degrees eastward. And back in the 1600s, it was really difficult to calculate longitude. Right. A ship leaving port would set two clocks, one for the prime meridian and another for local time. So crews would update their local time as they sailed, calculating it by using the position of the sun.
And by knowing the difference between these two times, you can calculate, like, the in-between longitudinal degrees and know your location. Yeah, you can math. Right.
But the clocks aboard these ships were not reliable. Like, picture pendulum clocks on rolling seas, right? Surrounded by salty air and changes in temperature or barometric pressure. The clock parts are going to warp. All of this can ultimately cause the clock to stray from the correct time. We call this clock drift. Ooh, I like that term, clock drift. Yeah, clock drift is dangerous.
Regularly throughout the 16 and 1700s, this accumulation of errors through ships so off course that it resulted in shipwrecks and lost lives and merchants and seamen began calling for a scientific solution. So the British government created the Board of Longitude and they announced a contest to solve this problem, the longitude problem.
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