Time Zone Problem I Can't Wrap My Head Around

[Stargate525]

Or: This is why I can't be alone at night with my thoughts.

So this is the layout. A man in a plane is flying west at speed precisely able to keep him at local noontime. Every hour, he radios down below him and asks for the time and the day. He starts on Wednesday.

As he progresses, he will eventually have to swap to Thursday like the rest of the world. But to do that, he's going to have to go from one person telling him he's noon on Wednesday to telling him he's noon on Thursday. How can a single timezone jump be twenty-four hours apart? Am I missing something obvious here?

[EdFred]

This is why we do everything in Zulu time in aviation.

Everywhere in the world, right now, it is 2225Z

But, even if we do go with local, there's the international date line in the middle(ish) of the Pacific where the west side of it, it's always a day ahead of the east side of it, even if only 1m apart.

Edited February 1, 2015 by EdFred

[Stargate525]

This is why we do everything in Zulu time in aviation.

Everywhere in the world, right now, it is 2225Z

Right, but that doesn't solve the crux of the problem; that somehow in this situation there is a person who is on one time zone, and an hour to the west of them they are not 1 hour behind, but 24.

[Tex]

I think you're just overthinking it- Everywhere in the world changes from one day to the next at some point. Due to this, it can be Wednesday in Wyoming and still Tuesday in Washington just like it would be if it were Wednesday in Russia and Tuesday in Germany. The day switch happens at some point all around the planet no matter what. People across the world are used to it.

[Stargate525]

I think you're just overthinking it- Everywhere in the world changes from one day to the next at some point. Due to this, it can be Wednesday in Wyoming and still Tuesday in Washington just like it would be if it were Wednesday in Russia and Tuesday in Germany. The day switch happens at some point all around the planet no matter what. People across the world are used to it.

I get that. It happens on the midnight turnover; it's 1am Tuesday in Chicago and 11pm Monday in Seattle.

But in this situation, somehow we've created a situation where it is 1pm Tuesday in New York, and noon MONDAY in Chicago. HOW?

[Albert VDS]

How can a single timezone jump be twenty-four hours apart? Am I missing something obvious here?

Because hes crossing the GMT-12 to GMT+12 border and gets into the next day.

Those 2 times zones have 24 hours between them.

[Newt]

When Magellan sailed around the world, (well, he died, but when his gaunt, starving former shipmates made it around the world), they missed one day in their logs. I think that this is what will happen here, too.

As you go around the world, you will build up on day of error per circumnavigation. There is not some inherent rule that makes this be the case, just the way that our time zones work.

[Sirrobert]

That is just one of the difficult things we have to keep up with in order to get the rest of the system to work right. Like leap years

[K^2]

Because hes crossing the GMT-12 to GMT+12 border and gets into the next day.

Those 2 times zones have 24 hours between them.

You just ended up with 25 time zones. But yes, there is an international date line in Pacific which gives you +24h when you cross it going East.

[Albert VDS]

You just ended up with 25 time zones.

Because there are 25 or 23 and 2 halves, depends on how you are counting.

[PakledHostage]

Fun fact: In winter time when the west coast of North America (Pacific Time) reverts to Standard Time and New Zealand observes Daylight Saving Time, the effective time difference between New Zealand and Pacific Time is only three hours (plus one day). That's the same as the difference between North America's Pacific and Eastern time zones (neglecting the difference in calendar day between New Zealand and North America). In other words, 11:00 AM in LA is 8:00 AM in Auckland.

And another fun fact: The date line effect is used as a major plot device in Jules Verne's "Around the World in Eighty Days".

[Red Iron Crown]

The thing the OP is missing is the International Date Line. When crossing it from east to west, instead of time going back by 1 hour it jumps forward by 23 hours. When crossing west to east, the clock jumps back 23 hours instead of jumping ahead 1 hour.

In the hypothetical situation described, when the pilot passes the dateline is when it stops being Wednesday and starts being Thursday.

[cantab]

Quite easily.

Time zones are referenced to UTC, which is the time in London more or less, and they range from 12 hours behind UTC to 14 hours ahead of UTC.

At some point our pilot will cross from a timezone which is well behind UTC to one which is well ahead of UTC. At this point it will around midnight Wednesday/Thursday in London.

The difference between for example UTC+13 and UTC-11 is the day. This is important for Pacific island countries, who might want to be generally on the same day as Australia/New Zealand or on the same day as the Americas - and either way don't want to be split within the country.

[K^2]

Because there are 25 or 23 and 2 halves, depends on how you are counting.

Ah, I see. Date line runs through the middle of a time zone. I did not anticipate that. Thanks for pointing it out.

[Nibb31]

Right, but that doesn't solve the crux of the problem; that somehow in this situation there is a person who is on one time zone, and an hour to the west of them they are not 1 hour behind, but 24.

Ever heard of the international date line ?

There are places in Alaska where you can actually see tomorrow from your doorstep

Edited February 2, 2015 by Nibb31

[K^2]

There are places in Alaska where you can actually see tomorrow from your doorstep

*Insert Sarah Palin joke here.*

[KerBlam]

What if you were flying at more than double the speed of the rotation of the earth, and you fly over the international dateline twice or more in one day?

[andrewas]

The date increments each time, but that gets cancelled by the time zones you cross.

[Nibb31]

What if you were flying at more than double the speed of the rotation of the earth, and you fly over the international dateline twice or more in one day?

Actually, if you fly around the Kiribati Islands, you can even cross the dateline several times. Good luck in knowing what time or even day it is when landing at a random island in that area!

[YNM]

Just use this. Saves a lot of headache. (hence why most astronomical timestamp uses it - it's easier when you have a joint observation across the globe).

[Red Iron Crown]

Just use this. Saves a lot of headache. (hence why most astronomical timestamp uses it - it's easier when you have a joint observation across the globe).

While that reduces the sort of error we're talking about (similar to using UTC for everything), the number of people one meets in everyday life who would understand that approaches zero.

[Lukaszenko]

Samoa and Tokelau skip a day for dateline change

[YNM]

Just use this. Saves a lot of headache. (hence why most astronomical timestamp uses it - it's easier when you have a joint observation across the globe).

While that reduces the sort of error we're talking about (similar to using UTC for everything), the number of people one meets in everyday life who would understand that approaches zero.

Uh, there isn't an infinite amount of people yet... And I'm not the only one who do.

Probably helps : think that there's two date-changing "line" exist in this world. The first one is what we call midnight, fixed against the sun; the second one is what we define to be the IDL (international date line), fixed against the Earth (it's there to avoid infinity loops of timezone, because Earth is round). Pass any of these lines and you'll change your date. Doesn't mean that anything doesn't happen in a single instance anyway.

[Red Iron Crown]

I don't see how the finite number of people in the world has anything to do with my statement, YNM. There are certainly people in some circles who understand Julian days, but they are few and far between in real life social interactions, at least in my experience. Your mileage may vary, of course.

[Beowolf]

While that reduces the sort of error we're talking about (similar to using UTC for everything), the number of people one meets in everyday life who would understand that approaches zero.

Better odds than you're thinking. Depends on who you hang out with. Julian dates are in common use in computer system administration, banking, insurance, navigation... Pretty much any field that frequently deals with "how many days between these two dates?" use it. Most may never find a reason to bring it up socially, though.