4 ms·

How I'm reading this - the argument is: we need timezones because, above all, we all want time to be fairly inline with daylight hours everywhere or at least so

How I'm reading this - the argument is: we need timezones because, above all, we all want time to be fairly inline with daylight hours everywhere or at least some approximation of a 9-5 workday? Eh, maybe. I'm not convinced.

bombcar 3y ago
that's basically it we want to be able to say "in the morning" and have it be reliably interpreted, because most human activities are actually tied to the sun and not to the clock (the clock is incidental for precise timing, but it's just reflecting the sun position).
- makeitdouble 3y ago
  The part that's really weird to me is those lines are latitude based, so Finland and South Africa share the same timezone. Sun wise, situations are a pretty different at any moment in the two countries. I wouldn't call the system "reliable" ( and those are not outliers, any zone with countries on opposite hemispheres has the same issue)
  - rypskar 3y ago
    >>Sun wise, situations are a pretty different at any moment in the two countries The sun is still at its high point at the same time of the day in both countries
    - makeitdouble 3y ago
      Doesn't that presume the earth is perfectly turning around its North/South axis ?
      - mixmastamyk 3y ago
        How would a rock spin other than "perfectly?"
        makeitdouble 3y ago
        It was more about the spin axis: timezones are vertically cut on a South/North line, while the earth rotation deviates from there. I actually couldn't find how much it deviates. I assume there's variation depending on the seasons as well.
        mixmastamyk 3y ago
        Not really, there’s a tiny bit of wobble but it moves over a thousands years or so, nothing to worry about. The axis doesn't change to my knowledge. https://en.m.wikipedia.org/wiki/Axial_precession https://en.m.wikipedia.org/wiki/Axial_precession Magnetic poles changing is not relevant it seems.
        makeitdouble 3y ago
        Thanks, that I didn't know. I'm kinda glad I tried to explain this, because I realize just how much I lack the proper words for it. The earth rotation wobbles a bit, but the axis itself is also not tilted towards the sun (it has no specific reason to) nor tilted towards the inside of the revolution axis relative to the sun. Basically the earth can be spinning on itself around any axis (let's call it A), while revolving around the sun on an unrelated axis (B). And neither A nor B has to be following the North/South axis. That's where the idea that a latitudinal timezone sees a similar solar cycle seems at odds to me. If an image can help more, the earth's self rotation and sun revolution in this video are clearly not aligned, nor any of them follow the North/South axis: https://www.britannica.com/video/151528/Earth-rotation-axis-revolution-Sun https://www.britannica.com/video/151528/Earth-rotation-axis-...
        mixmastamyk 3y ago
        Right they aren’t aligned. Sun’s axis is aligned perpendicular to the ecliptic. Earth is tilted 23.5 degrees from that. So North pole is tilted towards the sun on June 21 and South pole tilted towards it on December 21—why there are seasons. Doesn’t affect timezones to my knowledge.
    - brightlancer 3y ago
      > The sun is still at its high point at the same time of the day in both countries No. Helsinki's solar noon is about 35 minutes later than Cape Town's and 100 minutes later than Pretoria's. This is normal, because time zones are mostly broken into non-uniform 1 hour increments across 180 degrees of latitude.
      - garrickvanburen 3y ago
        yep - timezones are not straight lines - namely around the international date line.
jimbob45 3y ago
The alternative is that we have a DNS-style lookup of every city on earth which contains what each city has chosen for their daylight hours. You’d run into many more boundary-centric issues than with our columnar approach.
- brightlancer 3y ago
  > The alternative is that we have a DNS-style lookup of every city on earth which contains what each city has chosen for their daylight hours. We already have to do that: every business and government office (including schools) has their own hours (and holidays); even in the same city, people are not waking (or going to sleep) at a uniform time. Time zones are a 19th century solution to a 19th century problem.
fragmede 3y ago
China is one giant timezone, despite being 20% wider than the US. Imagine going to work at 6 am or coming home from work at 8 pm as the normal thing, depending on where you lived, not adjusted for local sun times.
- kawhah 3y ago
  Sounds fine.
  - humanrebar 3y ago
    "So you wake up at 14:00 over there?" "Yep!" "Huh. Weird. So how did Grandma's test results turn out?"

bombcar 3y ago

that's basically it we want to be able to say "in the morning" and have it be reliably interpreted, because most human activities are actually tied to the sun and not to the clock (the clock is incidental for precise timing, but it's just reflecting the sun position).

makeitdouble 3y ago
The part that's really weird to me is those lines are latitude based, so Finland and South Africa share the same timezone. Sun wise, situations are a pretty different at any moment in the two countries. I wouldn't call the system "reliable" ( and those are not outliers, any zone with countries on opposite hemispheres has the same issue)
- rypskar 3y ago
  >>Sun wise, situations are a pretty different at any moment in the two countries The sun is still at its high point at the same time of the day in both countries
  - makeitdouble 3y ago
    Doesn't that presume the earth is perfectly turning around its North/South axis ?
    - mixmastamyk 3y ago
      How would a rock spin other than "perfectly?"
      - makeitdouble 3y ago
        It was more about the spin axis: timezones are vertically cut on a South/North line, while the earth rotation deviates from there. I actually couldn't find how much it deviates. I assume there's variation depending on the seasons as well.
        mixmastamyk 3y ago
        Not really, there’s a tiny bit of wobble but it moves over a thousands years or so, nothing to worry about. The axis doesn't change to my knowledge. https://en.m.wikipedia.org/wiki/Axial_precession https://en.m.wikipedia.org/wiki/Axial_precession Magnetic poles changing is not relevant it seems.
        makeitdouble 3y ago
        Thanks, that I didn't know. I'm kinda glad I tried to explain this, because I realize just how much I lack the proper words for it. The earth rotation wobbles a bit, but the axis itself is also not tilted towards the sun (it has no specific reason to) nor tilted towards the inside of the revolution axis relative to the sun. Basically the earth can be spinning on itself around any axis (let's call it A), while revolving around the sun on an unrelated axis (B). And neither A nor B has to be following the North/South axis. That's where the idea that a latitudinal timezone sees a similar solar cycle seems at odds to me. If an image can help more, the earth's self rotation and sun revolution in this video are clearly not aligned, nor any of them follow the North/South axis: https://www.britannica.com/video/151528/Earth-rotation-axis-revolution-Sun https://www.britannica.com/video/151528/Earth-rotation-axis-...
        mixmastamyk 3y ago
        Right they aren’t aligned. Sun’s axis is aligned perpendicular to the ecliptic. Earth is tilted 23.5 degrees from that. So North pole is tilted towards the sun on June 21 and South pole tilted towards it on December 21—why there are seasons. Doesn’t affect timezones to my knowledge.
  - brightlancer 3y ago
    > The sun is still at its high point at the same time of the day in both countries No. Helsinki's solar noon is about 35 minutes later than Cape Town's and 100 minutes later than Pretoria's. This is normal, because time zones are mostly broken into non-uniform 1 hour increments across 180 degrees of latitude.
    - garrickvanburen 3y ago
      yep - timezones are not straight lines - namely around the international date line.

jimbob45 3y ago

The alternative is that we have a DNS-style lookup of every city on earth which contains what each city has chosen for their daylight hours. You’d run into many more boundary-centric issues than with our columnar approach.

brightlancer 3y ago
> The alternative is that we have a DNS-style lookup of every city on earth which contains what each city has chosen for their daylight hours. We already have to do that: every business and government office (including schools) has their own hours (and holidays); even in the same city, people are not waking (or going to sleep) at a uniform time. Time zones are a 19th century solution to a 19th century problem.

fragmede 3y ago

China is one giant timezone, despite being 20% wider than the US. Imagine going to work at 6 am or coming home from work at 8 pm as the normal thing, depending on where you lived, not adjusted for local sun times.

kawhah 3y ago
Sounds fine.
- humanrebar 3y ago
  "So you wake up at 14:00 over there?" "Yep!" "Huh. Weird. So how did Grandma's test results turn out?"