4 ms·

We have a monotonically increasing time, TAI (International Atomic Time). The problem is that people want 00:00 each day to correspond with midnight, and so we

We have a monotonically increasing time, TAI (International Atomic Time). The problem is that people want 00:00 each day to correspond with midnight, and so we need either (a) varying seconds or (b) leap seconds. So we have UTC (Coordinated Universal Time) which uses leap seconds to stay within one second of UT1, which is the mean solar time at 0 degrees of longitude, and which has variable seconds.

zarzavat 4y ago
Didn't we give up on having "the time" correspond to solar time in the 1800s with the advent of railways? Unless you live exactly upon a specific set of lines on Earth, 00:00 never corresponds to midnight, leap seconds or not.
- lalaithion 4y ago
  Fair. It would be more accurate to say that people want the time of midnight and noon to be consistent across ~decades and centuries (and if the leap second isn't going to happen the leap minute or hour almost certainly won't...).
  - Vvector 4y ago
    We already have a leap year, where we add an extra day every four years. So why could we not adjust the clock every 500 years when it gets out of sync by 20 minutes?
    - lalaithion 4y ago
      Yeah, I mean thats an option, but I basically expect that to cause a y2k-like level of emergency refactorizations as everyone realizes that their software isn't built for it. On the other hand, we already have leap seconds. They're not much of a problem.
      - arp242 4y ago
        > On the other hand, we already have leap seconds. Well, leap seconds are going away, so we don't. They were never adequate for the long-term anyway, as the "two leap seconds a year" scheme will break down as the earth's rotation slows over the centuries and more and more leap seconds will be needed. We're talking about an hour time drift over a few thousand years. Does that really matter? It's like caring what Julius Caesar's sense of "morning" or "evening" was. They never really solved any practical problem.

zarzavat 4y ago

Didn't we give up on having "the time" correspond to solar time in the 1800s with the advent of railways? Unless you live exactly upon a specific set of lines on Earth, 00:00 never corresponds to midnight, leap seconds or not.

lalaithion 4y ago
Fair. It would be more accurate to say that people want the time of midnight and noon to be consistent across ~decades and centuries (and if the leap second isn't going to happen the leap minute or hour almost certainly won't...).
- Vvector 4y ago
  We already have a leap year, where we add an extra day every four years. So why could we not adjust the clock every 500 years when it gets out of sync by 20 minutes?
  - lalaithion 4y ago
    Yeah, I mean thats an option, but I basically expect that to cause a y2k-like level of emergency refactorizations as everyone realizes that their software isn't built for it. On the other hand, we already have leap seconds. They're not much of a problem.
    - arp242 4y ago
      > On the other hand, we already have leap seconds. Well, leap seconds are going away, so we don't. They were never adequate for the long-term anyway, as the "two leap seconds a year" scheme will break down as the earth's rotation slows over the centuries and more and more leap seconds will be needed. We're talking about an hour time drift over a few thousand years. Does that really matter? It's like caring what Julius Caesar's sense of "morning" or "evening" was. They never really solved any practical problem.