why do we have different time zones instead of everyone being at the same current time and simply doing things at different hours of the day?

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Wouldn’t this prevent things like a country above another country (aka being in the same latitude) and having a different time zone (which never made sense to me); and other things that just don’t make sense in the current system?

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The whole idea with the time zones is that everyone should – with a small shift that isn’t really noticeable – have midnight in the middle of the night and noon in the middle of the day.

The way we track time is relative to the position of the sun. If you said “noon” no matter where you are you can determine the “noon” that is relative to you by the sun’s position in the sky.

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Two questions being asked here: 1. Why *are* things this way? and 2. Why might we want to *keep* things this way? I’m not sure about the historical context leading to the first answer, but I can come up with some ideas for the second answer:

– Right now, statements like “need to wake up at 5:00” are culturally unambiguous, because everybody in the world understands how awful it is to wake up at 5:00. Changing that will make it more difficult to communicate time information relative to your day/night cycle. (Though admittedly a weak point, since “after 5 hours of sleep” works just as well)

– In a legal context, it’s possibly easier to formalize “citizens must remain silent from 22:00 to 5:00” rather than having to go with some awkward description like “from -2 hours to +5 hours *relative to midnight*”, which is technically just what “22:00” and “5:00” already mean anyways.

– With a fixed time zone, DST would translate to needing to adjust all your memorized times, i.e. your meeting is now always at 3:00 instead of 2:00 – having locally shifting timezones allows you to keep the same times in your head even as the mapping from time to day changes. If you want to preserve this property you’ll still have weird +/-1 hour differences, which somewhat defeats the point.

– In most contexts where it matters (international trade, technology, etc.), people already use UTC as this universal source of constant time. But most things that depend on the time (i.e. primarily local events) aren’t really burdened by timezones existing.

– Changing things now would be a massive disruption to the entire ecosystem, people’s habits, etc. – look at how long it’s taking to standardize units of measurement across countries, to get a sense of how difficult it would be to standardize the units of time.

All in all it seems like an idea with some neat fringe benefits for frequent international travelers / collaborators, but probably relatively inconsequential to our everyday life and doubtfully worth the effort of disruption.

It wouldn’t work for many reasons. If you wanted to phone somebody far away you would still have to work out which part of their wake/sleep cycle they will be in. Just because their clock says the same as yours doesn’t meant that they will be doing the same thing you are. You would still have to look up their location in a table to find out if it was a good time to call. There would be a bigger variation because without the hour slots, everybody’s circadian rhythm would tend to revert to local Sun time.

This would just shift the problem of having to know what time is it now in US East Coast, to, say, what poeple would be doing at this time in US East Coast. Now I know it is 1PM in Hungary, my colleagues in NY are behind me 6 hours, so it is 7AM there. NOW as I know what I would do at 7AM I can put myself in their situation and know that they are probably waking up, having breakfast, drive kids to school, just as I would do at 7AM.
Given the time would be 1PM there as well as here in Hungary (although “AM” and “PM” would lost their meaning) now I would have to think about “what time it would have been there” so I do not disrupt their lives. It is usually custom that we don’t call people on phone during lunchtime. When would be lunchtime on this new system? Everytime. This problem would bring back timezone shift to the system indirectly (you would have fo calculate with that), which would make things harder.

If you have time zones varying with longitude, then the time is basically telling you “where is the sun in the sky right now”

Imagine you’re going on a long plane or train journey, travelling across multiple time zones. When you get off, you want to know if the shops will still be open, if it’ll be dark out, when you should start thinking about finding some food, that kind of thing. With time zones, this is easy. Your pilot tells you what the local time is, or you look for a clock when you get off, or your phone tells you, and now you have a pretty good idea of all of that stuff.

Without time zones, you know it’s 3 PM, but you have no idea what that means. Maybe you can take a guess based on how far away it is, but still; you don’t know if it’s light or dark out, how many people will be out on the streets, whether anything will be open.

And every time you travel you have to keep mentally adjusting to remind yourself _3 PM doesn’t mean mid afternoon here, it’s late evening_, which would be quite confusing, particularly if you travel a lot.

Or even simple things, like reading a news story and it says “the crime happened at 10 AM” but it’s in a distant country so you have no idea what that means.

Or you’re trying to schedule a meeting with people across what would currently be multiple time zones. Since the time zone is the same for everyone, you have to awkwardly ask everyone what times they’d be awake for rather than just looking at their time zone and immediately being able to work out something that makes sense for everyone.

There’s _no_ way you would get almost every country in the whole world to agree to radically change their time tracking.

You would have to agree on one time zone which would remain the “master” time. Good luck with that.

The Brits would say: “the official ‘zero’ timezone is UTC anyway, which sometimes corresponds to British time, so we should keep our time and let everyone else adjust theirs.”

Some United-States-of-Americans in Washington (I believe that’s East Coast?) would say: “no way, the United States of America is super important, we’ll keep our time and everyone else must adjust!”

Then the _other_ United-States-of-Americans on the West Coast would get really angry and say “you East Coastians are not going to tell _us_ what to do! We should keep the West Coastern time as the master!”

(I think there’s _also_ another different central time zone in the US?)

Meanwhile Russia says (imagine this in a terrible Russian accent): “Englandskies and Americanskies vill not dictate time zone change for Great Motherland! Russia vill be master of great time zone!”

And the Chinese just chuckle and shake their heads: imagine those silly Westerners try to force their silly time zone ideas on the glorious Chinese Communist Party!

Simply changing the formal timezones while allowing people to do things at different hours would do absolutely nothing to address the issue you mentioned. If such a thing passed legislation worldwide, people would just keep their present schedules regardless of what other people living in other countries at same longitude are doing.

You’d just make it unnecessarily difficult to communicate when people do things in different countries. I can say “Don’t call your uncle now, it’s midnight in London” instead of “Don’t call your uncle now, if he is maintaining a healthy sleep schedule, he is asleep and probably will be for the next 7-9 hours or so”

This is a thing but it’s use is limited to things like military applications where coordinated operations regularly take place over multiple time zones.

Names for it include Zulu time, Z-Time, Coordinated Universal Time and Universal Time Coordinated (UTC).

In the NATO phonetic alphabet “Z” is named “Zulu”, so to actually say “Z”Time over a radio you’d say “Zulu” Time, hence how it got its name. Why they picked Z ¯_(ツ)_/¯

“Everyone being at the same current time and simply doing things at different hours of the day” causes more problems than it’s worth.

With time zones, someone who wants to do business with a different time zone simply looks up the conversion (from either their own time zone or UTC or some other known time) and based on what time they get, they can determine when the people in that zone are most likely to be open/available for such business.

Without time zones – i.e. if everyone just used UTC, you would still need to figure out when someone in a different region is available to do business, so it’s not any *more* convenient. In fact it would be less convenient because you would depend on that person and/or business having a publicized schedule and sticking to it.