7 ms·

I never got what different time zones was supposed to accomplish. Why doesn’t everyone just use GMT? Why does the clock have to say 8 when you go to work? Would

by ambyra 3y ago

I never got what different time zones was supposed to accomplish. Why doesn’t everyone just use GMT? Why does the clock have to say 8 when you go to work? Wouldn’t it be better if we used the same clock everywhere?

AnimalMuppet 3y ago
A lot of us expect that "noon" has some connection to "sun at its highest point in the sky". Having that happen at 10 PM just feels wrong. But in fact, the military does have one standard time - Zulu time. Why have so many time zones? Well, they were originally introduced by railroads in the 1880s. Back then, "noon" was defined as "highest sun", so deviating very far from that was unreasonable. But also, railroads didn't run very fast back then. Each time zone was something like 700 miles across. That was enough to give enormous operational improvements. Removing the transitions (going to all one time zone) would have added only a little additional improvement.
- jameshart 3y ago
  "the military does have one standard time - Zulu time" Nah they don't. Skipping over the (common on the internet) parochiality of assuming that US military practice is just 'what the military does'... The US military certainly uses UTC/Zulu time for time stamping messages and coordinating operations globally, and timekeeping during extended missions (like submarine patrols, or air missions), but military bases and even surface vessels underway keep somewhat local time. They don't use Zulu time - that would mean the date changes in the middle of the day. You wouldn't be able to use words like 'next Tuesday' without having to disambiguate. It'd be crazy. Zulu - Z - is just the last of the alphabetically named military timezones: https://en.m.wikipedia.org/wiki/Military_time_zone https://en.m.wikipedia.org/wiki/Military_time_zone, which is a NATO standard.
  - bombcar 3y ago
    Zulu is used for aircraft scheduling, because it makes it simpler. Outside of that, the military recognizes two times, zero dark hundred and late as hell.
  - kawhah 3y ago
    I think you hit on the right answer. The justifications given above don't really make sense - "how would you know when to call Sydney" or "the sun being overhead at 10PM would feel strange". They are just rationalizations of a system that we're used to. But everywhere around the world, people want the date to change at a time when most things are closed and most people are asleep - which coincides with night-time for obvious reasons. This is effectively more important than having the date change at the same time for all of us.
    - humanrebar 3y ago
      I'm still not sure the costs outweigh the benefits, but I agree that this is the only concrete requirement that can't be solved with time, slow cultural change, and adjustments to some software.
gumby 3y ago
People used to set the town clock locally with noon when the sun is directly overhead. Also precision didn’t matter much when you weren’t trying to catch a train,
lucasmullens 3y ago
You need time zones to tell what's "early" or "late" in a place. If you're planning to call someone far away, picking a time "during work hours" becomes very difficult without time zones. You would have to consult some chart that describes when "work hours" are in each region which is basically just reinventing time zones.
- hyperhopper 3y ago
  This only matters in inter-timezone communication, which I'd wager is less than 0.0001% of communication. Let's not optimize for edge cases
  - SllX 3y ago
    I don't know what it is as a percentage, but globally there is in absolute terms significant amounts of East-West inter-timezone communication going on all of the time. Like literally, it does not stop happening and is happening right now. Percentages are misleading when the population is several billions of people conversing and conducting commerce at near-light speed on a global scale. Just the three hour difference between the East and West coast of the United States is significant enough to be worthy of consideration on when to call people on the other coast (or just expect them to get back to you through asynchronous comms) because people on the West Coast are on average waking up three hours later as measured by GMT.
  - allturtles 3y ago
    The same is true for the proposed global universal time. Without inter-timezone communication, everyone would just operate relative to their local solar noon, like they did pre-nineteenth century. The 'edge cases' of inter-timezone communication and travel are the only reason we need to care about any kind of coordinated time system.
- brightlancer 3y ago
  > If you're planning to call someone far away, picking a time "during work hours" becomes very difficult without time zones. Does everyone in your office work the same hours? We _already_ have the problem of "What are Bob's work hours" because most office workers don't work the same hours. Some folks come in early, some work late -- some come in late and leave early. That has been common for decades and has become even more pronounced with increased remote work, particularly across time zones. We shouldn't build our society around a myth of 9-5 office workers.
K7PJP 3y ago
What would abolishing time zones accomplish? https://qntm.org/abolish https://qntm.org/abolish
- humanrebar 3y ago
  No more arguments about daylight savings times!
jasontedor 3y ago
Let’s say we do that, use UTC everywhere. You live in London. It’s 3 PM. For you, that’s mid-afternoon. It’s your brother’s birthday. You want to phone him and wish him a happy birthday. He lives in Sydney. In a world without timezones, it’s 3 PM for him too. So you give him a call and start singing loudly when he answers. He’s mad at you because actually it’s the middle of the night and he’s sleeping. Or think about traveling. At home, you set your alarm for 6 AM. You really like waking up at this time even when you travel. You want time to hit the gym, and eat a nice breakfast. Now, in a world without timezones, you travel to SF. When your flight lands at 5 PM, what phase in the day is it? Local “morning”? Local “late evening”? Are you going to have a hard time catching a taxi? What time do people eat breakfast there? What time should you set your alarm for? So you need a translation layer from your location to another location to know what phase in the day it is for people in the other location. Is it their “morning”? Their “afternoon”? Their “business hours”? When do they sleep? That translation layer exists. That’s timezones. Abolishing timezones doesn’t make coordination problems easier. In fact, it makes them harder. The time on the clock might be the same around the world, but when people do things (wake up, eat breakfast, conduct business, grab a cocktail) would vary around the world. (Yes, it’s true there’s regional variance to these things today, but for the most part you can rely on morning having a rough relationship with when people wake up and sunrise, for example.)
- jpalawaga 3y ago
  These are all really obvious items. I sometimes wish people would put a bit of thought into things before engaging in conversation.
  - makeitdouble 3y ago
    These are only obvious if you never move outside of a few select zones. Time on the wall still being somewhat related to the sun doesn't even apply to countries with strong summer/winter variations. That's part of why killing DST has gained much more popularity in recent years. I think it's clinging to something that was an approximation in the best case scenario, and appears to be pure fantasy the more we dig into it and look around.
  - 3y ago
jcranmer 3y ago
A lot of people have already mentioned this, but the short answer is that you ultimately need a civil time that approximates local solar time. For example, you want to make sure that day changes happen at a time when there's little activity. Civil time doesn't need to be exact to solar time, and there's room for a fair amount of divergence, but when the divergence gets too great, people will spontaneously create their own civil time instead of using the official civil time (see, e.g., western China). It's better to have a minimal set of official civil times that are good enough for local purposes than have a large set of unofficial and semiofficial civil times.
drfuchs 3y ago
It's not going to work well when both the day of the week and the date change while you're having lunch.
WalterBright 3y ago
What we need to get rid of is Daylight Savings Time.
robsh 3y ago
Time zones were invented for time agreement across longitudes. We could easily do away with them if we included longitude, and everybody used a true solar noon clock. It could be automatic for GPS-enabled devices to maintain accurate solar noon time. Actually GPS satellites send a very accurate time on the signal, so you wouldn’t necessarily need a time server, except to know which epoch you’re on.

by ambyra 3y ago

AnimalMuppet 3y ago

A lot of us expect that "noon" has some connection to "sun at its highest point in the sky". Having that happen at 10 PM just feels wrong. But in fact, the military does have one standard time - Zulu time. Why have so many time zones? Well, they were originally introduced by railroads in the 1880s. Back then, "noon" was defined as "highest sun", so deviating very far from that was unreasonable. But also, railroads didn't run very fast back then. Each time zone was something like 700 miles across. That was enough to give enormous operational improvements. Removing the transitions (going to all one time zone) would have added only a little additional improvement.

jameshart 3y ago
"the military does have one standard time - Zulu time" Nah they don't. Skipping over the (common on the internet) parochiality of assuming that US military practice is just 'what the military does'... The US military certainly uses UTC/Zulu time for time stamping messages and coordinating operations globally, and timekeeping during extended missions (like submarine patrols, or air missions), but military bases and even surface vessels underway keep somewhat local time. They don't use Zulu time - that would mean the date changes in the middle of the day. You wouldn't be able to use words like 'next Tuesday' without having to disambiguate. It'd be crazy. Zulu - Z - is just the last of the alphabetically named military timezones: https://en.m.wikipedia.org/wiki/Military_time_zone https://en.m.wikipedia.org/wiki/Military_time_zone, which is a NATO standard.
- bombcar 3y ago
  Zulu is used for aircraft scheduling, because it makes it simpler. Outside of that, the military recognizes two times, zero dark hundred and late as hell.
- kawhah 3y ago
  I think you hit on the right answer. The justifications given above don't really make sense - "how would you know when to call Sydney" or "the sun being overhead at 10PM would feel strange". They are just rationalizations of a system that we're used to. But everywhere around the world, people want the date to change at a time when most things are closed and most people are asleep - which coincides with night-time for obvious reasons. This is effectively more important than having the date change at the same time for all of us.
  - humanrebar 3y ago
    I'm still not sure the costs outweigh the benefits, but I agree that this is the only concrete requirement that can't be solved with time, slow cultural change, and adjustments to some software.

gumby 3y ago

People used to set the town clock locally with noon when the sun is directly overhead. Also precision didn’t matter much when you weren’t trying to catch a train,

lucasmullens 3y ago

You need time zones to tell what's "early" or "late" in a place. If you're planning to call someone far away, picking a time "during work hours" becomes very difficult without time zones. You would have to consult some chart that describes when "work hours" are in each region which is basically just reinventing time zones.

hyperhopper 3y ago
This only matters in inter-timezone communication, which I'd wager is less than 0.0001% of communication. Let's not optimize for edge cases
- SllX 3y ago
  I don't know what it is as a percentage, but globally there is in absolute terms significant amounts of East-West inter-timezone communication going on all of the time. Like literally, it does not stop happening and is happening right now. Percentages are misleading when the population is several billions of people conversing and conducting commerce at near-light speed on a global scale. Just the three hour difference between the East and West coast of the United States is significant enough to be worthy of consideration on when to call people on the other coast (or just expect them to get back to you through asynchronous comms) because people on the West Coast are on average waking up three hours later as measured by GMT.
- allturtles 3y ago
  The same is true for the proposed global universal time. Without inter-timezone communication, everyone would just operate relative to their local solar noon, like they did pre-nineteenth century. The 'edge cases' of inter-timezone communication and travel are the only reason we need to care about any kind of coordinated time system.
brightlancer 3y ago
> If you're planning to call someone far away, picking a time "during work hours" becomes very difficult without time zones. Does everyone in your office work the same hours? We _already_ have the problem of "What are Bob's work hours" because most office workers don't work the same hours. Some folks come in early, some work late -- some come in late and leave early. That has been common for decades and has become even more pronounced with increased remote work, particularly across time zones. We shouldn't build our society around a myth of 9-5 office workers.

K7PJP 3y ago

What would abolishing time zones accomplish? https://qntm.org/abolish https://qntm.org/abolish

humanrebar 3y ago
No more arguments about daylight savings times!

jasontedor 3y ago

Let’s say we do that, use UTC everywhere. You live in London. It’s 3 PM. For you, that’s mid-afternoon. It’s your brother’s birthday. You want to phone him and wish him a happy birthday. He lives in Sydney. In a world without timezones, it’s 3 PM for him too. So you give him a call and start singing loudly when he answers. He’s mad at you because actually it’s the middle of the night and he’s sleeping. Or think about traveling. At home, you set your alarm for 6 AM. You really like waking up at this time even when you travel. You want time to hit the gym, and eat a nice breakfast. Now, in a world without timezones, you travel to SF. When your flight lands at 5 PM, what phase in the day is it? Local “morning”? Local “late evening”? Are you going to have a hard time catching a taxi? What time do people eat breakfast there? What time should you set your alarm for? So you need a translation layer from your location to another location to know what phase in the day it is for people in the other location. Is it their “morning”? Their “afternoon”? Their “business hours”? When do they sleep? That translation layer exists. That’s timezones. Abolishing timezones doesn’t make coordination problems easier. In fact, it makes them harder. The time on the clock might be the same around the world, but when people do things (wake up, eat breakfast, conduct business, grab a cocktail) would vary around the world. (Yes, it’s true there’s regional variance to these things today, but for the most part you can rely on morning having a rough relationship with when people wake up and sunrise, for example.)

jpalawaga 3y ago
These are all really obvious items. I sometimes wish people would put a bit of thought into things before engaging in conversation.
- makeitdouble 3y ago
  These are only obvious if you never move outside of a few select zones. Time on the wall still being somewhat related to the sun doesn't even apply to countries with strong summer/winter variations. That's part of why killing DST has gained much more popularity in recent years. I think it's clinging to something that was an approximation in the best case scenario, and appears to be pure fantasy the more we dig into it and look around.
- 3y ago

jcranmer 3y ago

A lot of people have already mentioned this, but the short answer is that you ultimately need a civil time that approximates local solar time. For example, you want to make sure that day changes happen at a time when there's little activity. Civil time doesn't need to be exact to solar time, and there's room for a fair amount of divergence, but when the divergence gets too great, people will spontaneously create their own civil time instead of using the official civil time (see, e.g., western China). It's better to have a minimal set of official civil times that are good enough for local purposes than have a large set of unofficial and semiofficial civil times.

drfuchs 3y ago

It's not going to work well when both the day of the week and the date change while you're having lunch.

WalterBright 3y ago

What we need to get rid of is Daylight Savings Time.

robsh 3y ago

Time zones were invented for time agreement across longitudes. We could easily do away with them if we included longitude, and everybody used a true solar noon clock. It could be automatic for GPS-enabled devices to maintain accurate solar noon time. Actually GPS satellites send a very accurate time on the signal, so you wouldn’t necessarily need a time server, except to know which epoch you’re on.