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I hope that, when they redefine UTC, they define a new name for it. UTC has been the same timescale since it started; the history of redefinitions of GMT is a h

I hope that, when they redefine UTC, they define a new name for it. UTC has been the same timescale since it started; the history of redefinitions of GMT is a horror-story. I guess what I'm really saying is that UTC-without-LS won't be UTC; rather, we'd declare that the new universal civil-time timescale is to be UTC-without-LS. You could carry on computing old-fashioned UTC after the transition; but one wouldn't generally use UTC to render civil-time for display.

sgtnoodle 4y ago
Leap seconds are determined manually, though, so it seems like there's no practical difference other than UTC's error from solar time going out of spec?
- denton-scratch 4y ago
  > other than UTC's error from solar time going out of spec? Well, yeah. Except that if it's not in-spec, it's not UTC; it's something else, and it shouldn't be called UTC. If you don't change the name, you would end up unable to compare two UTC times without also knowing which version of UTC the two times were given in.
  - sgtnoodle 4y ago
    I don't follow. UTC with no more leap second updates isn't a new version. It's the same timebase, just without any future updates to the leap second table. If the folk that maintain UTC decide to stop adding or subtracting leap seconds, it's not a fork in the timebase. That fork already happened with TAI. TAI was the same as universal time in 1958, and has progressed without any leap seconds. The current offset between TAI and UTC is 37 seconds. We could all agree to switch unix time to TAI, but there would be a 37 second discontinuity. I currently work on autonomous aircraft, and we use GPS time internally for avionics. The monotonicity is very nice for correctness when developing real time code. Outside of avionics, it's very confusing for people that tend to work in UTC. I've written table based timebase converters a few times now.
unnah 4y ago
Since the French-speaking world has started to acknowledge that English is the modern lingua franca, perhaps we could now reach agreement to call the new system UCT for "Universal Coordinated Time".
Nullabillity 4y ago
This is effectively just an agreement to _stop_ redefining UTC every couple of years.
- denton-scratch 4y ago
  Leap-seconds are a fundamental part of the definition of UTC. Declaring a leap-second doesn't amount to declaring a new timescale. Abolishing the leap-second, however, does declare a new timescale.

sgtnoodle 4y ago

Leap seconds are determined manually, though, so it seems like there's no practical difference other than UTC's error from solar time going out of spec?

denton-scratch 4y ago
> other than UTC's error from solar time going out of spec? Well, yeah. Except that if it's not in-spec, it's not UTC; it's something else, and it shouldn't be called UTC. If you don't change the name, you would end up unable to compare two UTC times without also knowing which version of UTC the two times were given in.
- sgtnoodle 4y ago
  I don't follow. UTC with no more leap second updates isn't a new version. It's the same timebase, just without any future updates to the leap second table. If the folk that maintain UTC decide to stop adding or subtracting leap seconds, it's not a fork in the timebase. That fork already happened with TAI. TAI was the same as universal time in 1958, and has progressed without any leap seconds. The current offset between TAI and UTC is 37 seconds. We could all agree to switch unix time to TAI, but there would be a 37 second discontinuity. I currently work on autonomous aircraft, and we use GPS time internally for avionics. The monotonicity is very nice for correctness when developing real time code. Outside of avionics, it's very confusing for people that tend to work in UTC. I've written table based timebase converters a few times now.

unnah 4y ago

Since the French-speaking world has started to acknowledge that English is the modern lingua franca, perhaps we could now reach agreement to call the new system UCT for "Universal Coordinated Time".

Nullabillity 4y ago

This is effectively just an agreement to _stop_ redefining UTC every couple of years.

denton-scratch 4y ago
Leap-seconds are a fundamental part of the definition of UTC. Declaring a leap-second doesn't amount to declaring a new timescale. Abolishing the leap-second, however, does declare a new timescale.