The world is not enough

[Baluncore]

Also, I once had three vernal equinoxes in a row before finally having another autumnal equinox.

I guess that means you are well sprung.

 

[DaveC426913]

I once had three vernal equinoxes in a row before finally having another autumnal equinox.

If that lasts longer than four hours, see your doctor.

 

[.Scott]

This is when the OP discovers what happens to puzzle threads after they are solved - they become a home to this sort of enlightened discourse.

 

[red_ed]

the original problem spec was in error.

In the original spec, it was postulated that the sun was over Greenwich, two ob

TL;DR: Viewed from above, the world has 24 hours. But it doesn't add up.

Though experiment: imagine yourself floating above one of the poles of the earth. Since I'm in the Northern Hemisphere I will use the North pole. Looking down at Noon Greenwich time, the sun is directly above Greenwich.

Now freeze the tableau and imagine yourself as an infinitely fast runner, starting at Greenwich and running West, across oceans and cities and all that stuff. As you run you wil cross time-lines: 11am, 10am,...until you reach the terminator between today and yesterday, 12:01 am. One more step puts you into yesterday. Leave this imaginary observer in place and return a new observer to Greenwich.

Observer 2, starting at noon Greenwich, starts running East, crossing timelines: 1pm, 2pm...11:59pm. One more step and your observer crosses into tomorrow. He/she/it is also face-to-face with observer #1. Two observers. Three days (Yesterday, Today, Tomorrow) all at the same point.

It doesn't work. Yet we live it daily.

this problem spec contains an error. Observer 1 and 2 facing each other across the line of midnight are both inside the same day. If either crosses the midnight line they do not transition to another day, they move one hour in 'clock time' but no date changes.


The idea of there being three days at one point devolves from my misunderstanding of the date line.

Thank you all for your assistance.

 

[russ_watters]

The sum of my net global travel, has me travelling 1½ laps of the Earth from West to East.

What does that mean? Because I'm pretty sure the sum of my [net (?)] global travel has me around halfway back from the moon. Or do you mean you were born in the US but now live in India? But anyway, I've done exactly one circumnavigation, on a trip to the Philippines where I traveled West on both legs.

 

[Baluncore]

What does that mean?

Born in the UK, now live in the antipodes. I have been backwards and forwards a few times, but mostly they cancel, leaving 1½ to the East.

You and I have the same winding number, ±½ .

 

[OmCheeto]

TL;DR: Viewed from above, the world has 24 hours. But it doesn't add up.

...

Did you know that it takes 48 hours for a day to pass?
This was probably the oddest thing I learned while playing Wordle.

 

[A.T.]

Observer 1 and 2 facing each other across the line of midnight are both inside the same day.

Yes. At noon in Greenwich the whole world agrees on what day it is.

If either crosses the midnight line they do not transition to another day, they move one hour in 'clock time' but no date changes.

Yes, in this special case that's what effectively happens.

More generally speaking, they adjust 1 hour for crossing a time zone line, and 24 hours in the opposite direction for crossing the date line, resulting in a 23 hours time-shift.

Only if that 23 hours time-shift goes beyond the boundary of their current day, they also have to adjust their current date accordingly. But when it's noon in Greenwich the 23 hours time-shifts stay within the same day for both directions of crossing the date line.