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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

#131

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…

> to the point that to get the equinoxes/solstices back to where they 'should' be 10 days had to be removed with the Gregorian calendar Note that the equinoxes and solstices are officially supposed to be on the 25th. By the time of Julius Caesar, that had diverged, but the divergence in reality made no impact on the date of the official solstice. The Gregorian calendar could easily have put the solstices back on the…

By the time of Julius Caesar, the solstices were on the 25th, which is the reason why Christmas is celebrated on that day.

The Gregorian calendar has not restored the time of Julius Caesar, but the time of the First Council of Nicaea (325 AD), when the rule about how to compute the date of the Easter was established.

From the time of Julius Caesar to 325 AD, more than 3 days of drift had accumulated, so the Gregorian calendar would have required 13 or 14 days of correction.

When many countries transitioned to the Gregorian calendar much later, they had to add additional correction days to the initial 10-day difference, about 1 day per century.

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

#132

The worst bug I ever dealt with in a 20 year career was a leap second bug (back in 2012). Servers all slowed down dramatically very suddenly, CPU saturated. No relevant code changes or changes in traffic. Turns out, they just got into that state due to a leap second. Some Livelock bug. A restart fixed everything. It wasn't just our site that went down. If I recall correctly, many other large sites (like Reddit, Linke…

Me too! In my case postfix locked up and stopped sending mail there was a massive queue. I checked the logs and saw the same second twice and that's when I learned about leap seconds. Since then I have a reminder in my calendar every 6 months to check if ones been announced. Thankfully we've only had two.

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

#133
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.

Astronomers do not need leap seconds, because even with this adjustment UTC cannot be used to determine anything in astronomy.

Astronomers need either true time, which is TAI, to be used in computing the positions of celestial bodies, and they need for observations the so-called Sidereal Time, which is not a time but the angle between a coordinate system attached to the Earth and an inertial system of coordinates attached to distant celestial objects that have negligible angular movement (in the past those were distant stars, now they are distant galaxies or quasars).

The Sidereal Time can be computed in a complex way from TAI, because it is determined by the periodic rotation and precession of the Earth and by various superposed periodic or random movements.

The UTC is not adjusted to match the current true rotation angle of the Earth, which you can measure by looking up to the stars, but it is adjusted to match within 1 second a fictitious angle that would be the rotation angle of the Earth-Sun direction corresponding to an Earth that would rotate uniformly both around itself and around the Sun, so that the duration of a day would have been constant.

In reality, the duration of a Solar day, i.e. the time between 2 consecutive noons, varies a lot during the year, by a large fraction of an hour (by about a half of hour peak-to-peak), so using UTC directly for estimating the position of the Sun gives a very big error, of many minutes of hour.

So what you need for astronomy is to know the current TAI and you need a Sidereal Time calculator, which you need for knowing in what direction to point your telescope, to find a given celestial object.

UTC cannot be used directly in astronomy, but only after passing either explicitly or implicitly through TAI. The fact that astronomical almanacs are published using UTC in their tables is obfuscating this, because the values in the tables have not been computed using UTC, but everything has been converted to UTC to match the time that is presumably shown by the watch or clock that the almanac user may have.

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

#134

The idea that if being dark at 12pm in 20k years will bother anyone is absurd. The shift will happen so slowly that the only people who will even realize it happened are historians and history buffs. Really the idea that there will enough civilizational continuity that our current timekeeping infrastructure and systems will continue unbroken for that long is insane.

Changing a global time system is not a trivial task. We’re still using a calendar developed over 400 years ago and just making minor tweaks. Without some central global authority, change is unlikely. And even with that, it would be extraordinary disruptive. The middle for the day, on our time keeping devices, being light outside goes all the way back to the first sundials over 3,000 years ago. Small and regular maint…

>The middle for the day, on our time keeping devices, being light outside goes all the way back to the first sundials over 3,000 years ago.

Most of the world is perfectly fine with 12:00 not being synchronized with high noon [0]. And some jurisdictions still semiannually f*k with it further using DST. Generously assuming the current time keeping system will survive for ~6k years (looking at the leap seconds accumulation rate for the last 50 years) we can just shift timezones by one hour.

[0]: https://64.media.tumblr.com/4a9a4613f057d3b5f17ec548e6ac06d1...

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

#135

Earlier quoted context omitted.

> One 'answer' to this concern is to have a 'leap hour' or something in the future We've had 27 leapseconds in the last 54 years [1] - an average of 0.5 seconds per year. At that rate, solar time will drift by 60 seconds over the course of 120 years. Drifting by 10 minutes will take 1200 years. The leap hour will be in 7200 years, around year 9226. [1] https://en.wikipedia.org/wiki/Leap_second

> The leap hour will be in 7200 years, around year 9226. 7200 years ago the Neolithic revolution was still in full swing and many of the most famous megaliths like Stonehenge hadn’t even been built yet. The first real state, the Sumerian civilization, hadn’t formed yet in Mesopotamia. Personally, I’m very comfortable making this someone else’s problems 7200 years from now. If they’re still having basic coordination i…

> 7200 years ago the Neolithic revolution was still in full swing

Older folks at Göbekli Tepe grumbled that climate change wasn't real. As far as they were concerned, the Sumer and Indus Valley kids were playing with fire and didn't know squat. The older generation just couldn't understand the crazy architecture over in Egypt and the slangy "new wave" movement at Salisbury Plain. It always seemed that the shiftless youth there just loitered and smoked and invented new expressions to frustrate communication. And everyone could agree that no one liked their so-called music!

https://en.wikipedia.org/wiki/G%C3%B6bekli_Tepe

https://en.wikipedia.org/wiki/8.2-kiloyear_event

https://en.wikipedia.org/wiki/Sumer

https://en.wikipedia.org/wiki/Indus_Valley_Civilisation

https://en.wikipedia.org/wiki/Old_Kingdom_of_Egypt

https://en.wikipedia.org/wiki/Stonehenge

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

#136
post #129

Earlier quoted context omitted.

As another poster already said, there will be 25-hour days at some time. The dinosaurs had days with fewer hours than us.

Where there fewer hours or were those hours just different length? Now we have locked in second extremely hard underpinning all of our measurements. But you could consider that you have same number of hours in a day and length of those hours has changed...

You could look at it either way. I couldn't say which system the dinosaurs actually used.

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

#137
post #119

Earlier quoted context omitted.

Sure; but I happen to be one of the dozens of people who do not live in UTC. So you have to do the conversion at some point _anyway_. If your app presents me data making the assumption that _my_ day is always 86400s, it will be _wrong_.

You do not have to do the conversion. It is just for presentation for you and the users. You do not have to read or know anything about TZ.

Do you consider implementing filters like “filter these items to those that have happened in a given day/week/month” a “presentation issue” too?

Because you need TZ awareness to implement that in a way that most humans expect.

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

#138
post #123

Earlier quoted context omitted.

you can use TAI (international atomic time, basically UTC without leap seconds) if you want to be serious about it I'm a fan but it's rare for anyone else to agree!

The problem with TAI is that the rest of the world uses UTC. So you can use TAI on a small island and then you have to convert to and from UTC. My hobby kernel is based on TAI internally. And it constantly converts to and from UTC.

The rest of the world should abandon UTC completely. It's not suitable for time keeping because butt scratching hairless monkeys mess with it.

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

#139
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.

They already got to that conclusion, but because of computers.

https://rin.org.uk/news/624222/Leap-Seconds-To-Be-Phased-Out...

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

#140
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.

They already got to that conclusion, but because of computers. https://rin.org.uk/news/624222/Leap-Seconds-To-Be-Phased-Out...

That’s super interesting—I didn’t know that.

Before modern standardization, maintaining calendars and clocks was typically the responsibility of states or similar authorities, often guided by astronomers. Now it seems that international organizations are effectively following the early UNIX/POSIX model, and astronomers no longer have the same authority over timekeeping.

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