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  • 2020 may have felt like it lasted forever,

  • but it was actually the shortest year in decades.

  • In fact, it was 1.3 milliseconds shorter.

  • The planet is now spinning faster than it has any time in the last half-century,

  • with 2020 containing 28 of the fastest days on record since 1960.

  • And 2021 is expected to be even faster...

  • which has ignited a fiery debate about what we should do to keep the world on track.

  • It may sound weird, but shifts in a planet's spin are actually normal.

  • Things like the pull of the moon,

  • jet stream winds,

  • and plate tectonics all have an effect.

  • Just like an ice skater draws in their arms to spin faster,

  • anything that moves mass closer to Earth's axis speeds up the planet's spin,

  • making the days a few milliseconds shorter.

  • It doesn't seem like much, but these subtle changes in Earth's spin

  • can cause major headaches for anyone trying to keep their clocks in sync.

  • But first, here's a little context on how our timekeeping has evolved.

  • Before we had cell phones, computers, or GPS to tell time, we had the Sun.

  • Ancient civilizations measured time using Earth's rotation relative to the sun

  • with devices like sundials.

  • We know this today as solar time.

  • Around 150 AD, Ptolemy divided Earth's 360 degrees of latitude and longitude

  • into 60 equal parts, into thefirst minute”, and then again, into a “second minute”, the basis for a second.

  • The development of quartz clocks in the 1930's made timekeeping even more precise,

  • and for the first time allowed us to measure variations in Earth's rotation.

  • Then atomic clocks revolutionized timekeeping.

  • In 1955, the National Physics Laboratory in England built the first accurate cesium clock,

  • and twelve years later, the General Conference on Weights and Measures redefined the second,

  • based on this crazy number of oscillations of a cesium atom.

  • This ultra-precise definition of a second is the foundation of International Atomic Time,

  • the average of hundreds of atomic clocks worldwide, making it our most accurate time keeper.

  • Atomic time can measure the spin of the planet down to the millisecond.

  • But the increase in accuracy comes with a downside.

  • Since atomic time ticks away at an incredibly constant rate,

  • it doesn't slow-down or speed-up with the spin of the Earth.

  • So, over the years atomic time has slowly drifted out of sync with the fluctuations of the planet.

  • Whenever the difference between solar time and atomic time

  • threatens to exceed 0.9 seconds,

  • a leap second gets added to Coordinated Universal Time to make up for the difference.

  • UTC is kept using atomic clocks, but with all those leap seconds added in.

  • To date, we've added 27 leap seconds since 1972.

  • The extra second gets squeezed in at midnight UTC.

  • Which is where the heated debate comes in.

  • Those who want to abolish the leap second say that in addition to being cumbersome,

  • it would take 5,000 years to notice even a one hour difference

  • between Earth's rotation and the atomic clock.

  • And when one was added in 2012,

  • the reservation system used by Qantas airlines collapsed,

  • and several websites including Reddit, Mozilla, and Gawker,

  • crashed when their systems failed to handle the extra second.

  • However, those in favor of the leap second argue that the technical issues are overblown.

  • Just a few years later in 2015, another second was added

  • and there were only a few minor hiccups.

  • The standoff is real and countries have already taken sides,

  • with the U.K. and Russia in favor of keeping leap seconds,

  • and countries like the U.S. and China advocating their drop.

  • At the 2015 World Radiocommunication Conference held by the U.N.,

  • countries couldn't come to an agreement,

  • so they decided to put off their decision till their next conference in 2023.

  • But no matter how long they debate, the Earth will continue to spin.

  • And it's up to the International Earth Rotation and Reference Systems Service, or IERS,

  • to determine if a year needs a leap second or not.

  • Last year Earth's rotation was fast,

  • and didn't need a leap secondat least, in the traditional sense.

  • Because it was spinning so fast,

  • the average day was estimated to be .05 milliseconds shorter than a typical 24-hour period.

  • Because of this, the group considered something they never had before: adding a negative leap second.

  • Instead of gaining a second, we would lose one.

  • And this year, scientists expect it to be even speedier!

  • While the group ultimately decided not to add this negative leap second last year,

  • it's possible that they might have to when they meet again this June.

  • All I know is when they finally make a decision,

  • we'll all be saying, it's about time.

  • We talked about removing a second from our clocks, but what about time itself?

  • Can it ever run backward?

  • Check out this video from Julian that explains how time might not reverse like physicists thought.

  • Have some cool science you'd like to see us cover?

  • Let us know in the comments below and as always, thanks for watching Seeker.

2020 may have felt like it lasted forever,

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Scientists Are in a Race Against Time and Earth’s Rotation

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    Summer posted on 2021/06/30
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