Leap Seconds, Smear Seconds, and the Slowing of the Earth
Unsung Science
CBS News
4.9 • 1.1K Ratings
🗓️ 17 December 2021
⏱️ 38 minutes
🧾️ Download transcript
Summary
The earth’s spinning is slowing down. Any clocks pegged to the earth’s rotation are therefore drifting out of alignment with our far more precise atomic clocks—only by a thousandth of a second every 50 years, but that’s still a problem for the computers that run the internet, cellphones, and financial systems.
In 1972, scientists began re-aligning atomic clocks with earth-rotation time by inserting a leap second every December 31, or as needed. It seemed like a good idea at the time—until computers started crashing at Google, Reddit, and major airlines. Google engineers proposed, instead, a leap smear: fractionally lengthening every second on December 31, so that that day contains the same total number of seconds. But really: If computer time drifts so infinitesimally from earth-rotation time, does anybody really care what time it is?
Guests: Theo Gray, scientist and author. Geoff Chester, public affairs officer for the for the Naval Observatory. Peter Hochschild, principal engineer, Google.
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Transcript
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| 0:00.0 | The Earth's rotation is slowing down, very gradually, but enough that it's drifting out of |
| 0:09.0 | sync with our atomic clocks, the ones that run our internet, cell phones, and financial |
| 0:14.3 | systems. |
| 0:15.3 | Since the late 50s, they drifted apart by 37 seconds, cumulatively. |
| 0:19.6 | So how do we, well, so leap seconds is what people do. |
| 0:25.5 | Yes, leap seconds. |
| 0:28.0 | We add one second to each year as needed, which is great unless it crashes your software. |
| 0:34.4 | And there were funny reports of some crashes in Google service, and that really caught |
| 0:39.8 | our attention. |
| 0:41.0 | Today on Unsung Science, the Earth's time, computer time, and the battle to manage the difference. |
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