"To authorities responsible for the measurement and distribution of time" is just the best preamble ever.
Sounds like something out of a Douglas Adams novel.
Or XKCD. I love patch day.
No leap second will be introduced at the end of December 2026
41–50 of 259 posts
Re: No leap second will be introduced at the end of December 2026
#42As one HN comment said years ago: I feel leap seconds have always lived in the wrong abstraction layer. They should live in the same abstraction layer that does leap days and daylight savings: the time zones.
god that would be awful. Can you imagine time zones being one second off from each other. Or two or three? ah yes, india is GMT+4:30:03, where europe is GMT+0:59:58
Re: No leap second will be introduced at the end of December 2026
#43"To authorities responsible for the measurement and distribution of time" is just the best preamble ever.
For many years, the title of the leadership role over the various precise time products at the USNO was "Director of the Directorate of Time"
Re: No leap second will be introduced at the end of December 2026
#44As one HN comment said years ago: I feel leap seconds have always lived in the wrong abstraction layer. They should live in the same abstraction layer that does leap days and daylight savings: the time zones.
The changes in Earth's rotational speed that leap seconds help account for affect the whole globe. Why shouldn't the effects be noted in the global time standard?
Re: No leap second will be introduced at the end of December 2026
#45Does this mean the negative leap second isn't happening anymore?
There's an opportunity to insert or remove a leap second twice a year. They only decide about 6 months in advance of each opportunity what to do (leap second, skipped second, or do nothing).
Re: No leap second will be introduced at the end of December 2026
#46Earlier quoted context omitted.
It’s a huge problem. The most common approach to address it is called smearing; the duration of each second for a 24 hour period ahead of the “leap” is adjusted. For strict ordering systems this works as each device maintains time sync with the global clock, the duration of a clock cycle is just slightly different. I think this was in the original Spanner paper, actually. Some rare systems use monotonic oscillator se…
I wonder if that's what electricity producers do? If you are selling 50 or 60 Hz service, an extra second here or there must really mess things up.
Clocks used to be able to use the 60Hz cycle to track time, and grid providers would run slightly slow or fast ("time error correction") to get back into sync. A leap second would just be part of this.
I believe in the US this error correction has been discontinued in the East and in Texas, but is still done in the West for some kind of non-clock "inadvertent interchange" reasons I don't understand.
Re: No leap second will be introduced at the end of December 2026
#47What causes the unpredictability in this? I would have guessed we have earth's rotation and orbit down to many decimals. Does geological activity, weather, or something else cause rotation speed differences that we just can't predict?
Yes, all of those and more. Our measurement precision is much better than the year-to-year first and second derivatives of day length. https://datacenter.iers.org/singlePlot.php?plotname=Bulletin... has the most relevant plot to this; the vertical jumps reflect leap seconds. (IERS has other plots for other dimensions of rotation, but I like this one.)
Very interesting, I wonder what happened in 2020 that causes the rotational speed to start drifting the other way?
Pandemic -> more people working from home -> less people in tall office buildings -> faster rotation (like a skater pulling in their arms).
Probably not remotely true but it would be funny.
Re: No leap second will be introduced at the end of December 2026
#48Notice they only said leap second . Meanwhile.... International timekeepers to vote on changing the leap second to a leap hour https://www.scientificamerican.com/article/international-tim... ( https://archive.ph/GnQUj https://news.ycombinator.com/item?id=48842329 )
really, my I just don't have the time to keep up with this.
A leap hour wouldn't affect you.
In practice it will never affect anyone because it's a legal fiction, but even if you pretend to believe we would actually introduce this "leap hour" it would be in the distant future long after we're all dead and if there are still humans who have any idea the year 2026 happened they're not sure which of Donald Trump, Taylor Swift, Tony Stark and John McClane were real people.
Edited to add:
This is such a ridiculously long time frame that they might not be sure whether we were worried about climate change, for them that's either a disaster they survived (and maybe most didn't) or it's a weird blip in their historical charts which they struggle to explain. Did our civilisation do something very, very stupid? There is a flammable gas deep underground, did we set fire to it because we were crazy? Why the hell would we have done that? There are signs we deliberately set fire to the coal which is a toxic rock also found underground? That would explain the global climate going nuts. Maybe it was a ritual or something. Ancient people are mad.
Re: No leap second will be introduced at the end of December 2026
#49> The difference between Coordinated Universal Time UTC and the International Atomic Time TAI is : > > from 2017 January 1, 0h UTC, until further notice : UTC-TAI = -37s This means the atomic clock is behind the solar clock by 37 seconds? I also don’t understand the reference to 2017.
Apparently December 2016 was the last time a leap second was inserted, at least that's what Wikipedia says: https://en.wikipedia.org/wiki/Leap_second
we were ought to insert a negative leap second, but cowards got too afraid it would break code
Re: No leap second will be introduced at the end of December 2026
#50What causes the unpredictability in this? I would have guessed we have earth's rotation and orbit down to many decimals. Does geological activity, weather, or something else cause rotation speed differences that we just can't predict?
In short, yes, the weather, geology, and signicantly, human movement of water via aquifer draining and dam building, as well as glaicial and ice melts, all contribute to unpredictable changes in the earths rotational period, as well as the axis of rotation. The models for this are IIRC trigonometric polynomials of fairly low order, so even if we could model the unpredictability perfectly, truncation error would limit our ability to distribute the model at super high accuracy. The existing models are built in to, eg, satellites, so you can't just make them arbitrarily complex.
Fun fact: leap seconds will stop being a thing soonish. I think they phase out in 2035, with a delay because Russia needed time to update glonass satellites.
(Note: on mobile, this is from memory, details need checking ;))