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Comment by CryZe | Hacker News Reader

How is this supposed to work? The rotation of the earth is not a constant. So we either scrap UT1 ("the atomic clock") or UTC ("the calendar"). Neither sound like an actual option. The latter would imply that at some (far off) point in the future you wake up at like 10pm as UTC and UT1 are now entirely mismatched (you may as well get rid of all time zones at that point).

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TAI - atomic clock, ignores earth rotation.

UT1 - based on Earth's rotation only, strictly 86400 seconds per day; length of each second varies; takes a heck of a lot of effort (and time) to measure accurately.

UTC - has same length of a second as TAI, but (for now) tracks UT1 to a precision of +/- 1 second. To achieve that, can have days that are 86399, or 86400, or 86401 seconds long.

None of 3 is planned for scrapping. The only change discussed in TFA is to fix UTC day to 86400 seconds (at cost of letting it drift further away from UT1).

Oh right, I confused the terminology, but the point still stands mostly.

It's a minor problem. One minute off in a hundred years is something we can all live with.

Can GPS handle this? Or is it under a different time standard?

The article mentioned GPS uses UT1

GPS has its own time thing, kinda fixed offset from TAI iirc

I'm not saying that we can't, but saying that we can seems quite brave (and by "brave" I mean foolishly reckless) without actually trying it. I, for one, am not so sure. There is a lot of stupid stuff about calendars and clocks (of which DST is worst by far), but at least nothing is really drifting.

Is it important that midnight is actually midnight? I don't know. I would prefer it to be, but perhaps I can just update my knowledge on when the midnight actually is once or twice a year. Perhaps it isn't a big deal at all. But I wouldn't dare to claim that "surely there can be no problems with it".

And, yes, that kinda means I don't support the leap second removal. It wasn't great, but eventually fixing the software written by incompetent people sounds more like a solution, than breaking the existing solution and making both competent and incompetent people alike eventually come up with a new one (to abolish it as well after 100 more years).

> Is it important that midnight is actually midnight?

Midnight is almost never at midnight.

Let's talk noon, specifically solar noon, as it is easier to visualize. Solar noon varies throughout the year, and based on the position in the timezone.

Solar noon for two cities in Eastern Time Zone: 11:29:16 - Boston 12:22:36 - Atlanta

Tomorrow, solar noon in Atlanta will be 12:22:50, 14 seconds later than today. No one notices a 14 second shift from one day to the next. As you can see, solar noon is almost never at clock noon, yet no one complains about that. Who would notice a 1 minute shift over 100 years?

The programming problem is made vastly more difficult because the leap seconds are not known in advance. When a new leap second is announced, every dependent system has to be updated.

I propose waiting a thousand years, so that the difference builds up to an hour, and then handle the adjustment as part of the daylight savings reform, which should just about have worked its way through the U.S. Congress and the EU institutions by then.

No. You’d need to actually change all the calendars. for example, an event recorded as happening at UTC 0 doesn’t get changed by a time zone change. And yet the hour you’ve accumulated is a “real” hour that’s accumulated in the number of seconds you think has elapsed since 0. You could of course keep track of when those leap seconds applied but now you have to have an almanac to compute the difference between two time stamps to account for all the smearing.

In my opinion, leap seconds are accumulated so slowly that the impact of abolishing leap seconds won't be noticeable in daily life for a couple hundred years.

As the article said, many countries jump forwards and backwards an entire hour twice a year and after the adaptation period we don't notice

> The CGPM — which also oversees the international system of units (SI) — has proposed that no leap second should be added for at least a century, allowing UT1 and UTC to slide out of sync by about 1 minute.

So there are two things to note. First is that it takes a long time for the seconds to add up, and second is that when we're looking into the deep future the current system of leap seconds won't be enough even if we do keep them.

> The latter would imply that at some (far off) point in the future you wake up at like 10pm as UTC and UT1 are now entirely mismatched (you may as well get rid of all time zones at that point).

We (or our descendants) can try to fix Earth rotation. All is needed is a big enough rotating mass with a variable speed of rotation.

UTC is the atomic clock (TAI minus 37 seconds currently); UT1 is "Earth time".

We would use UTC. UT1 would end up only being used by astronomers and whoever else cares about the Earth's rotation.

By the time UTC and UT1 diverge enough to matter, humanity will have either destroyed itself or come up with a new time standard.

If it gets too bad we can just leap-hour back onto schedule, way easier. (alter the tables that hold the existing offsets - this is done all the time)

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