4 ms·

Ya, and Unix time decided they could fool people into thinking they had all 3, and as a result, every couple of years, time "jumps backward" by one second. It's

by bloppe 2y ago

Ya, and Unix time decided they could fool people into thinking they had all 3, and as a result, every couple of years, time "jumps backward" by one second. It's hands down the worst option to use as the basis for a computing system that needs accurate timestamps, and it's made software developers really resent leap seconds. Now the BIPM decided to "get rid" of leap seconds in UTC a couple years ago. I hope they come to their senses before 2035 when the change takes effect. Here's what will happen: Rather than inserting a leap second every 1-2 years to keep UTC in sync with solar time, they plan to defer the problem to once every 100 or so years, and just insert like 50 leap seconds all at once. Think about that for a second. If leap seconds are so bad, how in the hell is the world going to deal with 50 of them at once after a century of oblivious complacency? They won't. They'll just say "Look, it's not worth it to have leap seconds in UTC anymore". Then, UTC will forever be just a constant offset away from TAI. But we already have TAI. Why not just use TAI as your "source of truth", and let UTC be UTC? We'll have to introduce a new system to take the place of UTC and be in-sync with solar time; like how UTC used to be.

nemetroid 2y ago
If we wait until UTC and UT1 differ by one hour, dealing with the adjustment will be no more difficult than dealing with time zones.
- moefh 2y ago
  I thought that was the plan when they decided to give up on leap seconds. I don't get the insistence on keeping nominal seconds-alignment (or even minutes-alignment) between the clock and the sun's position; we already don't experience it in practice. Timezone regions are fudged all over the world[1] for political and practical reasons, but even if they weren't, people living near one timezone edge don't experience the "sun noon" at the same time as people living near the other edge, even though they share the same clock time. [1] just look at the map here: https://en.wikipedia.org/wiki/Time_zone https://en.wikipedia.org/wiki/Time_zone
  - bloppe 2y ago
    It has nothing to do with time zones. People can deal with weird time keeping practices, but distributed software systems can become completely borked. It's happened before in all sorts of different ways. Transaction order can get messed up. Event queues can drop or duplicate events. Obviously, it's a big problem, otherwise people wouldn't be so intent on getting rid of them. And having a leap hour instead of a leap second would be a whole order of magnitude worse, especially if it occurs after hundreds or thousands of years of people writing software that's oblivious to the phenomenon. But completely getting rid of leap seconds for UTC is misguided. We already have TAI, which is literally just UTC without leap seconds. If leap seconds are messing with your system, just use TAI. Don't make UTC a slightly worse version of TAI. I feel like I'm taking crazy pills.
    - mattpallissard 2y ago
      > I feel like I'm taking crazy pills. I always told our new-hires to avoid thinking too deeply about computer timekeeping if they value their sanity.
      - bloppe 2y ago
        Time can only be measured by clocks (oscillatory systems). It's a slippery concept for which humans have a natural, flawed intuition. But if you understand your clock(s) really well, then timekeeping makes perfect sense. There's just a lot of clocks around. There's Unix time, UTC, TAI, smeared UTC, stop-the-clock UTC, UT1, and lots of others. Make sure you understand the clocks your system is using and how they relate to one another, and you can keep your sanity.
    - nemetroid 2y ago
      > I feel like I'm taking crazy pills. Civil society around the world has decided on UTC as the basis for time. What’s easier, convincing everyone to switch to TAI or changing the definition of UTC? I would guess it’s the latter.
    - moefh 2y ago
      > It has nothing to do with time zones. [...] And having a leap hour instead of a leap second would be a whole order of magnitude worse [...] The idea is exactly to not have a leap hour, UTC is kept completely untouched. Everyone changes their timezone instead, exactly like we already do with daylight savings, except this would happen only once every few thousands of years instead of twice a year.

by bloppe 2y ago

nemetroid 2y ago

If we wait until UTC and UT1 differ by one hour, dealing with the adjustment will be no more difficult than dealing with time zones.

moefh 2y ago
I thought that was the plan when they decided to give up on leap seconds. I don't get the insistence on keeping nominal seconds-alignment (or even minutes-alignment) between the clock and the sun's position; we already don't experience it in practice. Timezone regions are fudged all over the world[1] for political and practical reasons, but even if they weren't, people living near one timezone edge don't experience the "sun noon" at the same time as people living near the other edge, even though they share the same clock time. [1] just look at the map here: https://en.wikipedia.org/wiki/Time_zone https://en.wikipedia.org/wiki/Time_zone
- bloppe 2y ago
  It has nothing to do with time zones. People can deal with weird time keeping practices, but distributed software systems can become completely borked. It's happened before in all sorts of different ways. Transaction order can get messed up. Event queues can drop or duplicate events. Obviously, it's a big problem, otherwise people wouldn't be so intent on getting rid of them. And having a leap hour instead of a leap second would be a whole order of magnitude worse, especially if it occurs after hundreds or thousands of years of people writing software that's oblivious to the phenomenon. But completely getting rid of leap seconds for UTC is misguided. We already have TAI, which is literally just UTC without leap seconds. If leap seconds are messing with your system, just use TAI. Don't make UTC a slightly worse version of TAI. I feel like I'm taking crazy pills.
  - mattpallissard 2y ago
    > I feel like I'm taking crazy pills. I always told our new-hires to avoid thinking too deeply about computer timekeeping if they value their sanity.
    - bloppe 2y ago
      Time can only be measured by clocks (oscillatory systems). It's a slippery concept for which humans have a natural, flawed intuition. But if you understand your clock(s) really well, then timekeeping makes perfect sense. There's just a lot of clocks around. There's Unix time, UTC, TAI, smeared UTC, stop-the-clock UTC, UT1, and lots of others. Make sure you understand the clocks your system is using and how they relate to one another, and you can keep your sanity.
  - nemetroid 2y ago
    > I feel like I'm taking crazy pills. Civil society around the world has decided on UTC as the basis for time. What’s easier, convincing everyone to switch to TAI or changing the definition of UTC? I would guess it’s the latter.
  - moefh 2y ago
    > It has nothing to do with time zones. [...] And having a leap hour instead of a leap second would be a whole order of magnitude worse [...] The idea is exactly to not have a leap hour, UTC is kept completely untouched. Everyone changes their timezone instead, exactly like we already do with daylight savings, except this would happen only once every few thousands of years instead of twice a year.