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No leap second will be introduced at the end of June 2026

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Re: No leap second will be introduced at the end of June 2026

#21

Post by paulddraper »

Vvector wrote: post #13

Leap Seconds need to be abolished. The only people who need it are Astronomers. They could just use an offset. Implementing leap seconds correctly is a huge burden, for no gain. Where I live, high noon today occurs at 1:03 PM. No one is complaining that it is 3 minutes (or 63 minutes) off. It's a non-issue for 99.9% of the population.

> The only people who need it are Astronomers.

And anyone that cares about the relationship of the time of day and the position of the Sun.

Granted, it's not a lot, only a minute per century.

Re: No leap second will be introduced at the end of June 2026

#22

Post by toast0 »

SeanDav wrote: post #10

I assumed that leap seconds could be determined algorithmically, it appears I assumed badly. This is a bit of a can of worms...

They basically are, the algorithm is something like:

At the beginning of january and july, observe the difference between UT1 and UTC. If the difference is >= 0.6s, a leap second will be inserted at the end of june/december. Publish the results here: https://hpiers.obspm.fr/eoppc/bul/bulc

Re: No leap second will be introduced at the end of June 2026

#24

Post by coldpie »

ralferoo wrote: post #20
coldpie wrote: post #14

Earlier quoted context omitted.

Hmm. I understand that perspective, but I'm not sure I agree. It does seem to matter over a relatively short & realistic time scale. According to the Wikipedia page, there have been 27 seconds added since 1972, which is only 44 years ago. At that rate, that's about 1 minute per 100 years. We have many systems that have existed for several centuries and I think it's not unreasonable to start making plans for systems t…

The problem is that Earth's rotation isn't consistently faster. Some years leap seconds need to be added, some years they need to be removed. Would be far better to leave them alone, let them average out, and as the GP said let the people who care about this add the offset they need.

> Some years leap seconds need to be added, some years they need to be removed.

Is that true? Per Wikipedia:

> Since [1972], 27 leap seconds have been added to UTC, with the most recent occurring on December 31, 2016. All have so far been positive leap seconds, adding a second to a UTC day; while a negative leap second is theoretically possible, it has not yet occurred.

Either way, it's due in part to Earth's rotation slowing down, so the average drift would still be non-zero.

Re: No leap second will be introduced at the end of June 2026

#25

Post by throw0101c »

tialaramex wrote: post #9
throw0101d wrote: post #7

Earlier quoted context omitted.

> The complexity goes up tremendously if some condition is rarely encountered: eg leap second. This means it gets pushed to a "corner case" and tested more lightly and more rarely. There is some talk of eliminating the leap second, which would over time have the Earth and sun diverge with regards to noon and such. One 'answer' to this concern is to have a 'leap hour' or something in the future (some future generation…

The calendar adjustments are because the planet's constant orbital period isn't a whole number of days. The leap seconds were an attempt to have wall clock time map to the planet's rotational angle consistently despite the problem that the planet's spin varies unpredictably. Yes the "leap hour" is a legal fiction of course. In reality in the event anybody cares about this in the distant future they will make the kind…

So lunar tidal forces are slowing the rotation, but (recently?) Earth mantle/core is causing a speed up, but climate change and melting ice is contributing to the slow down side:

* https://www.scientificamerican.com/article/leap-seconds-may-...

* https://scripps.ucsd.edu/news/global-warming-influencing-glo...

The general trend is slowing down. Apparently (?) once the day gets to be 24h+0.001sec (+1 millisecond), a leap second would occur about every 1000 days; then when it becomes 24h+0.002sec, a leap second would occur about every 500 days; when it reaches 24h+0.003sec, a leap second would occur about every year; etc.

Re: No leap second will be introduced at the end of June 2026

#26

Post by [deleted] »

throw0101d wrote: post #7
imglorp wrote: post #4

Responding to a deleted comment: > ... the "invisible infrastructure" of the web; balancing historical accuracy with the technical need to minimize zone fragmentation is a much more complex trade-off than it appears on the surface ... The complexity goes up tremendously if some condition is rarely encountered: eg leap second. This means it gets pushed to a "corner case" and tested more lightly and more rarely. At $wo…

> The complexity goes up tremendously if some condition is rarely encountered: eg leap second. This means it gets pushed to a "corner case" and tested more lightly and more rarely. There is some talk of eliminating the leap second, which would over time have the Earth and sun diverge with regards to noon and such. One 'answer' to this concern is to have a 'leap hour' or something in the future (some future generation…

[deleted]

Re: No leap second will be introduced at the end of June 2026

#27

Post by throw0101c »

netsharc wrote: post #8
throw0101d wrote: post #6

There was some talk about a negative leap second† a few years ago: * https://www.npr.org/2024/03/30/1241674216/climate-change-tim... † T23:59:58Z would have skipped/suppressed :59 and gone to T00:00:00Z.

You make it sound like time labels like "23:59:58Z" can perform actions (e.g. to skip or "suppress"). I had to look it up: https://www.timeanddate.com/time/negative-leap-second.html . In proper words, the clock ("the one humanity agrees to use) would skip 23:59:59Z. I wonder how much chaos a minute that only has 59 seconds would cause. Measurements would be off by that missing second (e.g. a pipeline delivering fuel…

> I wonder how much chaos a minute that only has 59 seconds would cause.

The FreeBSD folks test(ed?) their code for these things and it works:

* https://lists.freebsd.org/pipermail/freebsd-stable/2020-Nove...

Of course third-party userland code understanding what happens is another thing.

Re: No leap second will be introduced at the end of June 2026

#28

Post by layer8 »

himata4113 wrote: post #19

How about a leap minute instead so we only have to worry about this when it's not a problem anymore :)? We will either hit the fermi filter or accend intelligence.

The length of day increases by around 1.7 milliseconds per century long term (due to the moon’s gravity continuously slowing down Earth’s rotation), which without leaps seconds translates to around one total minute per century. Note that this is cumulative: next century you will need two leap minutes, and so on. Of course, there are significant shorter-term variations in Earth’s rotation due to other factors, so it isn’t quite that smooth in practice.

There was a resolution in 2022 to make a decision in or before 2035, to increase the allowable deviation from one second to a longer interval, like one minute. But that would become more frequent in the long run as well, and likely would still cause disruptions whenever it happens. Though on the other hand there would likely be a longer advance notice for it as well.

Re: No leap second will be introduced at the end of June 2026

#29

Post by amenghra »

throw0101d wrote: post #7
imglorp wrote: post #4

Responding to a deleted comment: > ... the "invisible infrastructure" of the web; balancing historical accuracy with the technical need to minimize zone fragmentation is a much more complex trade-off than it appears on the surface ... The complexity goes up tremendously if some condition is rarely encountered: eg leap second. This means it gets pushed to a "corner case" and tested more lightly and more rarely. At $wo…

> The complexity goes up tremendously if some condition is rarely encountered: eg leap second. This means it gets pushed to a "corner case" and tested more lightly and more rarely. There is some talk of eliminating the leap second, which would over time have the Earth and sun diverge with regards to noon and such. One 'answer' to this concern is to have a 'leap hour' or something in the future (some future generation…

IMHO the correct way to handle leap seconds would have been at the same layer as timezones, i.e. a display-only thing. Timezone databases are regularly updated, you push out leap second updates there. In the worst case, people's clocks are off by one second but all the underlying timing logic doesn't crash.

Re: No leap second will be introduced at the end of June 2026

#30

Post by wmf »

throw0101d wrote: post #7
imglorp wrote: post #4

Responding to a deleted comment: > ... the "invisible infrastructure" of the web; balancing historical accuracy with the technical need to minimize zone fragmentation is a much more complex trade-off than it appears on the surface ... The complexity goes up tremendously if some condition is rarely encountered: eg leap second. This means it gets pushed to a "corner case" and tested more lightly and more rarely. At $wo…

> The complexity goes up tremendously if some condition is rarely encountered: eg leap second. This means it gets pushed to a "corner case" and tested more lightly and more rarely. There is some talk of eliminating the leap second, which would over time have the Earth and sun diverge with regards to noon and such. One 'answer' to this concern is to have a 'leap hour' or something in the future (some future generation…

We had a leap hour yesterday...
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