Could the world be thrown into chaos by the first-ever 'negative leap second'!? | Latest technology in 5 minutes

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From space development, AI, and quantum technology to general scientific topics, I explain them from an engineer's perspective.
The concept is to deliver content that even those who think 'I'm not a science person, so this is too difficult...' can easily understand in 5 minutes.

Speaking of 'leap years,' everyone knows what that is, right?
Yes, that thing where February 29th only happens once every four years.
But have you ever heard of a 'leap second'?

You all know that time is determined by the time it takes for the Earth to rotate once, right?
And to adjust the 'gap' between the Earth's rotation and the time, a 'second' is occasionally added or removed. This is a 'leap second'.

By the way, adding a 'day' every four years to adjust for the time it takes for the Earth to orbit the sun (one year) is a 'leap year'.

Wait, adding just one second is no big deal, right?
If you thought that, you might have been right 30 years ago...
But in modern society, this 'one second' could cause a major problem!

🌎 The Earth's rotation is actually fickle

A day is exactly 24 hours. I'm sure everyone believes that.
But in reality, the speed at which the Earth rotates is not perfectly constant. It slows down and speeds up, albeit by a tiny amount.

If left alone, the gap between the Earth's rotation and the time would gradually grow!
It would be a disaster if the sun were setting on the horizon while it was still supposed to be daytime!!
That is why we have 'leap seconds' to reset that gap.

However, changes in the Earth's rotation speed are quite fickle. They are completely unpredictable.
So, unlike 'leap years' which are set to occur every four years, 'leap seconds' are irregular.
Moreover,
they are suddenly decided, like 'We're adding a leap second in six months!'

Since the 'leap second' system began in 1972, 27 leap seconds have been added so far.
Specifically, what happens is'23:59:60' is inserted between '23:59:59' and '00:00:00'.

🚅 Recently, is the Earth's rotation 'speeding up'!?

Wait? If it slows down and speeds up, isn't it bad to just keep inserting 'leap seconds'?

If you noticed that, you are extremely sharp!!
Yes, in fact, until now, the Earth's rotation has always been slowing down little by little.
So, leap seconds have been inserted. In other words, adjustments have only been made to delay the time.

However... recently, observational data has emerged showing that the Earth's rotation is speeding up a bit.
You might feel that rotating objects would gradually decelerate, but it's not that simple.

Last year, July 5, 2024, was the shortest day in recorded history, clocking in at '-1.66 milliseconds'.
Even this month, on July 10, the shortest day of the year was observed at '-1.36 milliseconds'.

If this continues,for the first time in human history,an adjustment to speed up time by one second, in other words,a 'negative leap second'will be necessary!!
That is what it means.

You might think, 'Adding a second is easy to understand, but how do you remove a second?' but this is simple.
The method is to jump from '23:59:58' directly to '00:00:00'.In other words, you skip '59 seconds'.

⌛ Is a negative leap second really such a big deal?

Yes, it is a big deal.

In our daily lives, it's normal to notice and adjust if a clock is off by two or three minutes.
A one-second deviation is within the margin of error; no one cares about it, and in the first place, you probably wouldn't even notice.
But in a world where everything is connected via a network, this one-second deviation can be fatal.

You may not have noticed, but even with the 'positive leap seconds' we've had until now, various troubles have occurred.
Stock exchange systems have stopped functioning properly, and airline check-in systems have gone down, causing flight delays...

Actually, I too...

I myself am one of the people who has been affected by a 'leap second' trouble.
It turned out there was a bug in a 'GPS module' that the company I worked for at the time had developed in the past.
We realized that after the 'leap second' scheduled to be inserted a few weeks later, products equipped with that GPS module could have their positions off by several kilometers.

With the time limit approaching, we were frantically scrambling to deal with it. Fortunately, we managed to avoid any major issues, but it makes me shudder to think what would have happened if we had realized it too late.

There is no precedent for a negative leap second...

Even with the 'positive leap second,' which has been implemented 27 times in the past, that many troubles have occurred.
Since there is no precedent for a 'negative leap second,' we won't know what kind of unexpected situations will occur in various systems until it actually happens.

It's been about 9 years since the last 'leap second'

Moreover, the last time a 'positive leap second' was implemented was at the end of 2016. That was 9 years ago.
Compared to back then, networks are now more deeply rooted in society. The damage caused by troubles might be even greater than it was then.

🚫 Actually, it's already been decided that 'leap seconds' will be abolished

Are 'leap seconds' that only create such troubles really necessary?
Actually, that debate has been going on for a long time.
And in 2022,
Let's stop using 'leap seconds'
was the conclusion, and it was internationally agreed toabolish 'leap seconds' by 2035.

In other words, the direction has shifted to:
'If it's going to cause this much trouble, isn't it okay if the time is off by a little bit?'
'Let's think about it again if the discrepancy becomes too large.'

However, the current outlook is that we might need a 'leap second' before it is abolished.
There is a possibility that the first-ever 'negative leap second' will be implemented around 2029!

If we're going to abolish it anyway, I wish we could just stop immediately...
but I wonder what will happen?
IT industry professionals around the world must be feeling nervous.

📝 Summary

Many of you might have thought, 'I can't believe there's such a big fuss over just one second!'
In modern society, where everything is connected and synchronized via networks, even a one-second discrepancy cannot be underestimated.

What will happen with the first 'negative leap second' in human history?
We should keep a close eye on future developments.