7 ms·

I think it's weird how people react with such horror to the idea that maybe, just maybe, it wouldn't represent any kind of problem to the people of the 23rd cen

I think it's weird how people react with such horror to the idea that maybe, just maybe, it wouldn't represent any kind of problem to the people of the 23rd century if 12:00 didn't correspond to the instant the sun was directly overhead, but instead a minute past. Nor would it cause any issue for people thousands of years from now if 12:00 was in the evening or the morning or any other part of the day or night. For those future people it would simply be the way things are, and it would stay that way their whole lives.

mjevans 2y ago
Noon already does not correspond to the sun overhead. Timezones, and IIRC the time of year and inclination relative to the equator matter too. However, irrespectively, it's basically never solar noon at noon if someone is using time zones rather than local solar time, which of course would be a custom timezone for that exact location.
- sfilmeyer 2y ago
  This article that I just came across does a nice job at explaining some of the nuances of solar noon https://www.timeanddate.com/astronomy/solar-noon.html https://www.timeanddate.com/astronomy/solar-noon.html . The time of year does matter a bit, but the effect is smaller than the effect of timezones. Their equation of time article includes a nice graph of the variations in time of solar noon at Greenwich. https://www.timeanddate.com/astronomy/equation-of-time.html https://www.timeanddate.com/astronomy/equation-of-time.html
  - Izkata 2y ago
    > This article that I just came across does a nice job at explaining some of the nuances of solar noon https://www.timeanddate.com/astronomy/solar-noon.html https://www.timeanddate.com/astronomy/solar-noon.html . And a related thing, the analemma - the sun's position at the same place on earth at solar noon over the course of a year doesn't resemble an arc, it's a figure-8: https://en.wikipedia.org/wiki/Analemma https://en.wikipedia.org/wiki/Analemma
lovecg 2y ago
Many parts of the world move forwards and back a full _hour_ every year. We complain about it but it’s mostly ignored. A gradual drift of a couple of minutes is fine.
- teruakohatu 2y ago
  Its not quite the same problem. Timezones are a transformation applied on top of UTC. If you are writing code, you are transforming the always increasing UTC to a more or less arbitrary dates and times. Moving backwards means you (your code) experiences the same time twice.
  - ffsm8 2y ago
    Keep in mind that the earth is round and timezones switch an hour by area, so there is always some drift between the suns position and midday. So from my point of view, they were spot on
    - jpitz 2y ago
      You might be surprised to learn that there are time zones that are not an integer number of hours different from UTC.
      - ffsm8 2y ago
        I'm always open to change my mind, but I struggle to see the relevance of that in this context. Are there timezone areas in the world which change their UTC differential fluidly throughout the year and by the yard to pin midday to the highest position of the sun? I'll definitely say that that'd not only surprise me but blow my mind if true! If there isn't ... Then what was your point?
        jpitz 2y ago
        You claimed that timezones change an hour by area. That's not the case. That's my point.
plesner 2y ago
It makes a lot of sense to not care about a slight amount of drift. But that already exists: that's what TAI is. Why make UTC into another TAI just slightly offset? Why not just switch to TAI? Or, if the 37 second difference between UTC and TAI is the problem they can make a new TAI-minus-37. What makes no sense is taking something useful, UTC, and redefining it out of existence. Then what time do you use if you really do care about drift? Do we invent a new UTC?
- modeless 2y ago
  > Why not just switch to TAI? That would be great. > Then what time do you use if you really do care about drift? Nobody uses UTC because they want to know where the Sun is to the nearest second. People who actually need to care about variations in the Earth's rotation speed (e.g. astronomers) already need far fancier stuff than just UTC. People use UTC because someone else made a mistake and decided they should use UTC, like a government standard, or an operating system vendor, or whatever. Unfortunately the best way to correct all those millions of mistakes is to redefine UTC rather than convince everyone in the world to simultaneously switch to TAI. > taking something useful, UTC, and redefining it out of existence I question that UTC is useful. What utility does it have over TAI, outside of interoperability with other people who are using UTC? Again, anyone who actually needs to care about Earth rotation speed changes already needs to use something better than plain UTC, and my argument in my original comment is that drift that is small on a scale of a human lifetime is not an actual problem for anyone alive today or in the future.
  - weberer 2y ago
    >That would be great. Well whats stopping you?
    - modeless 2y ago
      > interoperability with other people who are using UTC
- zokier 2y ago
  > Why not just switch to TAI? Getting the world to switch timescales is orders of magnitude more difficult that redefining currently used timescale. The latter can be done in the BIPM backrooms by small committee, the former needs action and agreement from pretty much everyone.
GuB-42 2y ago
Also, very few people today have the sun directly over their head at noon. If you don't live at the prime meridian, it is an abstract concept. And even if you do, there may be DST. In some countries, you can be hours off. Few people actually care about the precise earth rotation, and there are time bases for these people that are better than UTC anyways. Sunrise and sunset are important, but the middle of the day, not so much.

mjevans 2y ago

Noon already does not correspond to the sun overhead. Timezones, and IIRC the time of year and inclination relative to the equator matter too. However, irrespectively, it's basically never solar noon at noon if someone is using time zones rather than local solar time, which of course would be a custom timezone for that exact location.

sfilmeyer 2y ago
This article that I just came across does a nice job at explaining some of the nuances of solar noon https://www.timeanddate.com/astronomy/solar-noon.html https://www.timeanddate.com/astronomy/solar-noon.html . The time of year does matter a bit, but the effect is smaller than the effect of timezones. Their equation of time article includes a nice graph of the variations in time of solar noon at Greenwich. https://www.timeanddate.com/astronomy/equation-of-time.html https://www.timeanddate.com/astronomy/equation-of-time.html
- Izkata 2y ago
  > This article that I just came across does a nice job at explaining some of the nuances of solar noon https://www.timeanddate.com/astronomy/solar-noon.html https://www.timeanddate.com/astronomy/solar-noon.html . And a related thing, the analemma - the sun's position at the same place on earth at solar noon over the course of a year doesn't resemble an arc, it's a figure-8: https://en.wikipedia.org/wiki/Analemma https://en.wikipedia.org/wiki/Analemma

lovecg 2y ago

Many parts of the world move forwards and back a full _hour_ every year. We complain about it but it’s mostly ignored. A gradual drift of a couple of minutes is fine.

teruakohatu 2y ago
Its not quite the same problem. Timezones are a transformation applied on top of UTC. If you are writing code, you are transforming the always increasing UTC to a more or less arbitrary dates and times. Moving backwards means you (your code) experiences the same time twice.
- ffsm8 2y ago
  Keep in mind that the earth is round and timezones switch an hour by area, so there is always some drift between the suns position and midday. So from my point of view, they were spot on
  - jpitz 2y ago
    You might be surprised to learn that there are time zones that are not an integer number of hours different from UTC.
    - ffsm8 2y ago
      I'm always open to change my mind, but I struggle to see the relevance of that in this context. Are there timezone areas in the world which change their UTC differential fluidly throughout the year and by the yard to pin midday to the highest position of the sun? I'll definitely say that that'd not only surprise me but blow my mind if true! If there isn't ... Then what was your point?
      - jpitz 2y ago
        You claimed that timezones change an hour by area. That's not the case. That's my point.

plesner 2y ago

It makes a lot of sense to not care about a slight amount of drift. But that already exists: that's what TAI is. Why make UTC into another TAI just slightly offset? Why not just switch to TAI? Or, if the 37 second difference between UTC and TAI is the problem they can make a new TAI-minus-37. What makes no sense is taking something useful, UTC, and redefining it out of existence. Then what time do you use if you really do care about drift? Do we invent a new UTC?

modeless 2y ago
> Why not just switch to TAI? That would be great. > Then what time do you use if you really do care about drift? Nobody uses UTC because they want to know where the Sun is to the nearest second. People who actually need to care about variations in the Earth's rotation speed (e.g. astronomers) already need far fancier stuff than just UTC. People use UTC because someone else made a mistake and decided they should use UTC, like a government standard, or an operating system vendor, or whatever. Unfortunately the best way to correct all those millions of mistakes is to redefine UTC rather than convince everyone in the world to simultaneously switch to TAI. > taking something useful, UTC, and redefining it out of existence I question that UTC is useful. What utility does it have over TAI, outside of interoperability with other people who are using UTC? Again, anyone who actually needs to care about Earth rotation speed changes already needs to use something better than plain UTC, and my argument in my original comment is that drift that is small on a scale of a human lifetime is not an actual problem for anyone alive today or in the future.
- weberer 2y ago
  >That would be great. Well whats stopping you?
  - modeless 2y ago
    > interoperability with other people who are using UTC
zokier 2y ago
> Why not just switch to TAI? Getting the world to switch timescales is orders of magnitude more difficult that redefining currently used timescale. The latter can be done in the BIPM backrooms by small committee, the former needs action and agreement from pretty much everyone.

GuB-42 2y ago

Also, very few people today have the sun directly over their head at noon. If you don't live at the prime meridian, it is an abstract concept. And even if you do, there may be DST. In some countries, you can be hours off. Few people actually care about the precise earth rotation, and there are time bases for these people that are better than UTC anyways. Sunrise and sunset are important, but the middle of the day, not so much.