Because now 5PM is in the morning. And you can't even make sense of opening hours if you go to Shanghai or Melbourne. (Why are they open from 1AM to 1PM?)
"The terms "a.m." and "p.m." (ante meridiem and post meridiem) are strongly deprecated now, because they refer to the position of the Sun, not of the clock."
I am from Germany where time goes from 0:00 to 24:00 - so to me they are just arbitrary numbers.
"So to rephrase: I want to call my Uncle Steve in Melbourne. What time is it there?
It is 04:25 ("four twenty-five") there, same as it is here.
Does that mean I can call him?
I don't know."
If you want to know that, e.g. inform yourself of the current solar altitude at the respective place.
"...Well, put it this way. I'm in the UK. He's in Australia. How far ahead of me is he?"
> It is 04:25 ("four twenty-five") there, same as it is here. Does that mean I can call him?
To further strengthen that: Depending on which country in Europe you’re calling, a call at 7:00 may be okay, or one before 10:00 may be rude. A call past 18:00 may be rude, and people may be in bed at 21:00 – or people may not have even eaten dinner before 22:00.
This gets even more extreme when looking at China, where people living in the west of china will be off by 5 hours from local time.
> "To further strengthen that: Depending on which country in Europe you’re calling, a call at 7:00 may be okay, or one before 10:00 may be rude. A call past 18:00 may be rude, and people may be in bed at 21:00 – or people may not have even eaten dinner before 22:00."
You need to take into account cultural (and personal) details regardless, and those are usually understood based on patterns of human activity (e.g., "call before dinner") which is generally understood on the position of the sun, not the ordinality of the hour of the day. You might have dinner at 18:00, but that's because 18 marks an hour in the evening, not because there's something special about the number 18. Having a easy mapping between numbers and solar position is convenient.
Western Spain and eastern Germany are in the same time zone, but the position of the sun will be offset by 3 hours.
In the current world, timezones only cause confusion, and do not provide any of the benefits you think they do.
Timezones work okay-ish for the US and UK, but that’s because their timezones generally map to local time quite well, and they have a shared culture. Everywhere else, they’re purely rage-inducing madness, and useless.
China has abandoned timezones eons ago for that very reason.
> Western Spain and eastern Germany are in the same time zone, but the position of the sun will be offset by 3 hours.
To argue that the hour is supposed to track to some arbitrary precision is to argue against a straw man. They're approximations that help us communicate with each other. As is arguing that some current configuration of time zones is a problem so the idea of time zones in general is flawed. If western Spain and eastern Germany sharing the same time zone is problematic (which may be, but just saying "the position of the sun will be offset by 3 hours" doesn't mean it is practically), then we can decide to place them in other time zones.
> "In the current world, timezones only cause confusion, and do not provide any of the benefits you think they do. ... Everywhere else, they’re purely rage-inducing madness, and useless."
Having lived in time zones across the world while communicating with family and business partners in multiple time zones while doing so, I respectfully disagree. While you may find they don't provide benefits to you, to decree they provide no benefits for anyone in such an absolute sense is frustrating. Yes, there are tradeoffs regardless of the adopted system. To dismiss them out of hand is absurd.
I'm sympathetic to reducing rage-inducing madness in general. However, as it is very general, it makes it hard to address directly. Sometimes reductionist is used as a pejorative. In this case I would like to know specific examples so we can determine their root cause and see if it's essential or accidental.
I suspect there are other issues that arise in China with such a large area spanning such a longitudinal range. I'm sure there are trade offs.
> "I am from Germany where time goes from 0:00 to 24:00 - so to me they are just arbitrary numbers."
I'm very comfortable with (and prefer) a 24-hour clock myself. The advantage the 24-hour clock provides is that a.m. and p.m. are no longer needed to distinguish between morning and night, and there's no ambiguity with hour 12. They're not arbitrary numbers with respect to the (approximate) position of the sun in the sky.
A 24-hour vs 12-hour clock is orthogonal to the issue of time zones. I think the author's done a bit of a disservice by adding this detail here, as the issue is that you don't know from the hour whether it's morning or night.
> "Compute the difference of the solar altitudes."
This isn't a convenient calculation to make, and something that time zones already give us to a reasonable approximation. For example, (using a 24-hour clock):
It's 9:00 in New York (and Tokyo, since everywhere it's the same). Do I call? First, I have to look up the relative positions of the sun in London and Tokyo. How do I easily do that without any assistance? One quick (?) approximation would be to look up the longitudes.
New York City is at 74°W, Tokyo is at 143°E, that's a difference of 217°, or 60% of a day. So the sun is 60% further along in Tokyo than in NYC. Since we're not talking about changing the length of the day, how many hours is that? About 14½. How am I going to make that meaningful to me? Likely add it to the time, so I get 23:30. You could argue that they could put the differences on the map in terms of hours rather than doing the longitude calculations, but then you've just got (roughly) a time zone map.
If you have other thoughts on how to do this, please do share. I haven't been able to come up with a scenario that doesn't boil down to this, doesn't rely on a more sophisticated tool which isn't always available, and takes into account human psychology.
With time zones, I can easily find out how many hours Tokyo is ahead of London which can be found in a simple table or map (15). I add that to the current time: it's 24:00 in Tokyo. I know that it's the middle of the night.
I still need to take into account what I know of but I have to do this anyway, regardless of knowing the relative position of the sun, and that's usually mental calculation based on the relative position of the sun.
Time zones are a convenient short hand for computing the difference in solar altitudes and putting it into human understandable terms.
> A 24-hour vs 12-hour clock is orthogonal to the issue of time zones. I think the author's done a bit of a disservice by adding this detail here, as the issue is that you don't know from the hour whether it's morning or night.
I disagree: I don't know how native English speakers think about this, but the wording that am and pm stand for are references to sun positions while numbers are not.
They're orthogonal because you can change one without changing the other: 24-hour vs 12-hour clock is about how we label the passage of time throughout the day locally, roughly mapping the local position of the sun to an hour table. Time zones are a method of being able to use the same labels locally and translating between them. We can change to a 25 hour day, partitioning that into 5-hour segments we label α, β, γ, δ, and ε and still use time zones to know that 2β (because we can also choose this arbitrarily with varying measures of utility) is approximately the time when the sun is highest in the sky.
Another example: we could use 0 as noon and label hours + or - relative to noon, so 11 a.m. would be -1 and 1 would be 1 p.m. That would have the utility that you would know, roughly, relative darkness based on the absolute value of the hour. And again, you can change this independently of the choice whether to use time zones. This arguably makes more sense with respect to sun position: while the a.m. and p.m. label periods leading up to and after midday, the number used as part of that label is still arbitrary.
This makes it even more clear that we do fine some kind of measure of relative position of the sun in the sky useful. We want to be able to understand relative to the location of a point on the earth. Hours set locally do this. Using UTC everywhere does not. Yes, you can find situations where this isn't as important, but they're generally outside of the everyday human domain.
I encourage you to carry your ideas further than a one sentence description of disagreement: How do they apply across cultures? How are they practical? How would they be used in every day life? What are the implications? What are other reasonable alternatives? Please note I'm not saying they're not, but it's really hard to figure out exactly what you're getting at. My goal is not to construct a straw man to argue against, but any model that I may make to explore the issue further may be inaccurate because you've provided so little to base it on. In particular, I'd like to hear about your ideas on computing the difference in solar altitudes.
Eastern Time: open 2PM to 2AM UTC (Mon evening -> Sat morning)
PST: open 5PM to 5AM UTC (Mon -> Sat)
This makes exactly 0 sense.