Nixing the Chaotic Leap Second

Can't Stop Thinking About

- Darren Orf

SINCE THEIR INCEPTION OF THE LEAP SECOND 50 years ago, 27 have been added to our clocks to make sure Universal Coordinated Time aligns with our solar reality-sort of like how leap days or leap years keep our calendars from becoming a complete chronological mess.

Well, no more. Last year, government representatives at the General Conference on Weights and Measures decided to scrap the leap second, beginning in 2035 and lasting until at least 2135 (or until we discover a better method for adjusting our clocks).

What Is a Leap Second? // Human time has long been calculated by how long it takes Earth to complete a full rotation on its axis. However, there's just one problemEarth doesn't rotate at a uniform rate. Earthquakes, volcanoes, tidal forces, and even wind patterns can affect how fast or how slow the world turns.

This is a problem because the world is built on the extreme timekeeping precision of atomic clocks, baked into the programming of orbiting satellites, financial markets, and everything in between. Atomic clocks calculate a second as "9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom," and cesium atoms don't know (or care) how fast Earth spins. Over time, these discrepancies can sometimes be more than a millisecond per day. When those milliseconds add up, the world needs to add another second.