Why are time zones important?

I have a good idea about why they exist, but are they important?

Realistically if it is daylight in the Midwest from
6am-6pm, would it matter on the other side of the world if it was daylight between 6pm and 6am?

Is it mainly for commerce or is there another reason why timezones exist?

I think you mean to ask, “Are they strictly necessary?”

Not really. In theory, we could all use UTC nowadays. That would mean daylight hours in the US would more or less be what is currently midnight to noon.

The reason time zones exist at all is simply history. We didn’t always have fast transportation. Setting local noon as the time when the sun was directly overhead is very simple and reasonably accurate.

That changed when the locomotive came around. Suddenly, we could travel between two places fast enough that the local clocks don’t match. Rather than telling everybody “Let’s toss out a few thousand years of history and custom”, it was simpler to switch to time zones.

It’s noon, or mid day, when the sun is overhead in my part of the world. If you want noon to happen at midnight where you live, go ahead; but I’m not changing for you.

Seriously, time zones are a pretty recent invention when it comes to keeping time. The sun is the arbiter of days.

Also, the concept of “universal” time is already more or less used. That’s what UTC basically is. We offset a set number of hours based on that for local purposes.

Somewhat less seriously (but still actually pretty serious), can you imagine celebrating the coming of the New Year at what is now locally 7pm in New York, which is 4pm in Los Angeles, 9am in Tokyo, and 3am in Moscow? That’s messed up.

It is to keep the trains on time.

I thought that was Mussolini.

Actually, since all of those clocks would read “00:00 UTC”, I think it would make perfect sense.

But it would make perfect sense only in the context of the whole world ushering in the new year simultaneously. It would be a real pain when we’d all go back to work and school. What I mean is: For everyone to switch to UTC sounds nice in theory, but do you really want to switch from “2359 Mon Jan 6” to “0001 Tues Jan 7” right in the middle of lunch?

If you accept that human beings have a body clock that makes them want to be awake when the sun is up and sleep when the sun is down, having time zones makes things a little easier.

Suppose you’re a nationwide chain like Wal-Mart, or for that matter, Fox TV. You want your product/service to be available locally when people are most likely to be awake. If everyone is on UTC, you’d wind up with listing like “Open at 0300 in New York City, Boston, Washington, Philadelphia; Detroit and cities like that; 0400 in Minneapolis, Chicago, Kansas City, Dallas, Houston and places around them; 0500 in Denver, Phoenix and the Rocky Mountains; 0600 in California; and 0800 in Hawaii.”

It does make it a lot easier just to say to everyone, “Our stores open at 8:00 a.m.”

I was thinking along the same lines. I remember when TV promos would end with “Thursdays at 8, 7 Central”. It would be even more awkward if they had to announce all the time zones (don’t forget Alaska and Hawaii).

Would the days start and end at local midnight, or UTC midnight? If Friday became Saturday at lunchtime, what time does your bank close that afternoon?

I assume the kinks could somehow be worked out, but the way things are now is simpler. My dad was a pilot, and since they do everything by UTC, he used to set his watch to it. When I used to ask him what time it was, he’d just show me his watch. That wasn’t particularly helpful.

Very true. But there is another side to the story: Right now, when I see a website that says “Call our Customer Service people between 6 AM and 9 PM Central Time”, everyone outside of that time zone has to do the conversion.

The trouble is that it’s getting more and more inconvenient to reset clocks for summer time and time zone changes [insert photo of two cable boxes that both show a different wrong time the morning after the switch], so maybe we should just all use UTC and get it over with.

I’m always surprised to see how many people keep their computer/phone/watch on their home timezone when traveling across timezones, although I guess today that’s less common because these devices will adjust themselves automatically.

How do time zones keep Mussolini on time?

In Europe all trucks have an electronic tachograph that records their work hours. The machine records everything in GMT, but the time on the face of the recorder will usually be set to the local time. This means that there are no discrepancies when crossing time zones.

Now - if they would just do away with this summer/winter time nonsense…

One of the lines from the TV show MASH* that still cracks me up:

People organize their lives and their activities by dividing the day into night, morning, noon, afternoon, evening etc. Hours are just a way of fine-tuning and expressing this concept more precisely. “Evening” means the same to individuals in Los Angeles, New York, Moscow, Beijing and Melbourne, and so does “08:00 PM” or “20:00”.

My father, born 1906, once told me that there were two kinds of timekeeping in Philadelphia when he grew up. The clock on City Hall tower told sun time (actually, mean sun time, but that’s a whole nother story), while the clocks at the railroad station told “railroad time”, that is standard time. Since the 75th longitude passes through the NE corner of Philadelphia, I don’t see that they could have seriously differed, maybe by one minute. If I figure correctly, at 40 deg latitude, one minute on the clock is something like 12 miles. At any rate, he said that the clock in Media, PA, was three minutes later than the one in Philly. When all this local silliness disappeared. Probably during the war, when people had more important things to worry about.

But it is correct that the railroads were instrumental in getting standard time zones adopted. Now if only they had nipped DST in the bud (the change is a headache for them on the days of the change to/from DST). It was supposed to save power; it doesn’t.

AIUI, Mainland China does it more or less that that way. The whole country is on Beijing time.

So if sunrise today in Beijing is 8AM Beijing time, sunrise in the far west of the country will be around 1pm Beijing time. And folks there will break for lunch when the sun is high in the sky and their clocks say 4pm, and eat dinner shortly after sunset when their clocks say 10 pm. And then they’ll get up for work shortly before sun-up when their clocks say around noon.

It works for them, ~20% of humanity. Which proves it *can *be done. Whether it *ought *to be done is another question.

China Only Has One Time Zone—and That’s a Problem

If I need to send an e-mail to a customer in, let’s say, Germany, I might check the world clock on my phone and see that it’s 7:00 PM in Berlin. Thus, I can deduce that it’s after normal business hours in Germany, and that I shouldn’t expect a quick response. If everyone used universal time, I would have no clue what time of day it was where this customer lived.

The same question arises on a much larger scale (whole years instead of days) between the northern hemisphere and southern hemisphere. When it’s snowy and cold up north, it’s bright and sunny down there in Oz. So clearly, we should have time zones of latitude as well as time zones of longitude.