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Science & Nature
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The 61-Second Minute: How 27 Leap Seconds Secretly Broke the Internet
Since 1972, 27 leap seconds have been added to our clocks to sync atomic time with the Earth's slowing rotation. While keeping us aligned with the sun, this tiny adjustment has caused major chaos for computer systems, prompting a global decision to abolish them by 2035.
Have you ever seen a clock read 23:59:60? It sounds like a glitch from a science fiction movie, but this exact time has officially occurred 27 times since 1972. This is no error. It’s a “leap second,” a tiny, deliberate hiccup in global timekeeping designed to keep our hyper-precise digital world in sync with our wobbly, imperfect planet—often with chaotic consequences.
Two Clocks, One Planet
At the heart of the issue is a fundamental conflict: we operate on two different clocks. The first is astronomical time (UT1), based on the Earth’s rotation. It gives us our days and nights. The second is atomic time (UTC), the global standard kept by hundreds of atomic clocks that tick with unfathomable precision. The problem? The Earth is a sloppy timekeeper. Due to the gravitational pull of the Moon and Sun, its rotation is gradually, and unpredictably, slowing down. Our planet's day is now slightly longer than the 86,400 seconds defined by atomic clocks.
To prevent our civil time from drifting ever further from the position of the sun in the sky, scientists at the International Earth Rotation and Reference Systems Service (IERS) add a leap second whenever the discrepancy approaches 0.9 seconds. This correction keeps our clocks—and the sun—in alignment.
The Digital Mayhem of a 61-Second Minute
While this sounds like a neat solution for astronomers, it's a recurring nightmare for the digital infrastructure that underpins modern society. Computers and software are built on the rigid assumption that time always moves forward, and every minute has exactly 60 seconds. The appearance of a 61st second (23:59:60) violates this rule and can cause systems to crash, hang, or lose data synchronization.
This isn't just a theoretical problem. The leap second added on June 30, 2012, caused widespread outages, impacting major websites like Reddit, LinkedIn, and Gizmodo, and even grounding hundreds of flights in Australia's Qantas airline system. For system administrators, it's a regularly scheduled crisis. As one commenter on the topic aptly put it:
It's a pain in the ass for anyone who manages servers. Especially if you have a distributed system where it's absolutely critical that every server has the exact same time. It's not a fun day at work.
To sidestep this chaos, tech giants like Google and Amazon have developed a clever workaround known as a “leap smear.” Instead of adding one extra second all at once, they gradually add tiny fractions of a second to their internal clocks over a 24-hour period, effectively smearing the leap second so their systems never experience the disruptive 23:59:60.
The End of an Era and a New, Terrifying Problem
The repeated digital disruptions have finally led to a major change. In November 2022, the General Conference on Weights and Measures voted to officially abolish the leap second by 2035. After this date, UTC will no longer be adjusted, and our civil time will be allowed to drift away from solar time. Future generations, perhaps a century or more from now, may have to deal with a larger correction, like a “leap minute.”
But there’s a final, bizarre twist to this story. In recent years, the Earth’s rotation has unexpectedly begun to speed up. This has raised the unprecedented and alarming possibility of a *negative* leap second, where a second would be *removed* from the clock, jumping from 23:59:58 directly to 00:00:00. This is a far scarier prospect for programmers, as many systems designed to handle an extra second were never built to accommodate time going backward. This potential for even greater chaos has only added urgency to the decision to stop meddling with the clock altogether.
The story of the leap second is a fascinating clash between astronomical reality and digital precision. For half a century, we fought to keep them perfectly aligned. Now, we’ve chosen to prioritize our digital world, accepting that our time will slowly, imperceptibly, fall out of sync with the sun.