An easy birthday puzzle


image by y2bk

Have you ever celebrated your birthday in another time zone?

There’s some novelty to it, as you can celebrate both during local time and your “home” time as you please. This sort of unusual time accounting can translate into a few extra hours of celebration.

My friend loves doing this, and she came up with an even grander idea:

One year I am going to start celebrating my birthday the minute it’s August 11 somewhere in the world, and I’ll keep going until it is August 11 nowhere in the world.

So the question is: If you follow this rule, how much time will you be celebrating your birthday?

Leave your thoughts/ideas in the comment section as usual. I will post an answer with an explanation by Sunday.



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  • http://www.dial4cleanhome.com Ninad

    My Windows clock says there are timezones from GMT-12 to GMT+13. So you would be celebrating your birthday for 49 hours.

  • Vikas

    Hey

    The answer got to be 48 hours! 24 hours for the eastern most point to have that day and 24 hours for the western most point to catch up!

    Regards,

    Vikas

  • http://thehologram.blogspot.com Sailesh Ganesh

    It becomes August 11 earliest just east of the international date line (call it point A), and August 11 latest just west of the line (call it point B). If we assume an straight international date line from north pole to south pole, then August 11 will end at point A just as it starts at point B. Therefore, the total celebration time is 24 hours of August 11 in point A plus 24 hours of August 11 in point B, making it 48 hours in total.

    In reality though, the line is crooked. The most advanced time on earth is on the Line Islands of Kiribati, which are UTC + 14 hours, and the least advanced time is on Howland Island and Baker Island at UTC – 12 hours, making a difference of 26 hours between them. Therefore, your friend will be able to celebrate her birthday for a total of 50 hours.

  • Chandra

    MAXMAX:If you live just east of the international date line, you can celebrate for at most 2 days.
    MAXMIN:If you live just west of the international date line, you can celebrate for at most 1 day.

  • James

    you will be celebrating between 48 hours and 24 hours, but does depend on where somewhere is.

  • wh

    @Chandra- maybe I’m missing something, but why wouldn’t it be the same answer of 2 days irregardless of where you celebrated?

  • Sebastian

    It’s actually a whooping 50 hours. According to Wikipedia, Line Island is +14 of UTC, whereas Howard Island is -12 of UTC (those are the 2 extremes).
    So if I start celebrating at 0:00AM on Aug.11 (=10AM Aug.10 UTC) on Line Island, I can celebrate until it’s 24:00 on Howard Island (=12PM Aug.13 UTC).
    So I have 14+24+12=50!
    Here’s the map: http://en.wikipedia.org/wiki/File:Standard_time_zones_of_the_world.png
    I guess one could consider things like days being slightly longer on the equator or leap seconds(! http://en.wikipedia.org/wiki/Leap_second ), but that would only account for at most 1 minute.
    Daylight savings could possibly add another hour, but countries in +14 UTC or -12 UTC dont follow this convention. http://en.wikipedia.org/wiki/Daylight_saving_time

  • http://headinside.blogspot.com Grey Matters

    Chandra, where the friend lives shouldn’t make any difference as to how long the friend celebrates. She didn’t say anything about being in a particular time zone, just that she’d start celebrating when someplace in the world had her birthday.

    Here’s my approach and solution:

    Just west of the dateline, it turns from 11:59 PM on August 10th to 12:00 AM on August 11th, so the friend starts celebrating.

    After another hour, it hits 12:00 AM on August 11th, and so on until the final time zone. So far, it’s taken 24 hours just for every place to START August 11th. The last time zone will be the last place to see any part of August 11th, but that won’t happen for another 24 hours.

    24 hours to get the days started everywhere, and another 24 to finish it up in the final time zone, gives a total of 48 hours (or 2 days) regardless of where the friend lives.

  • Scott

    I’d say 2 days. August 11th would ‘begin’ as soon as it hits the international date line. It would take 24 hours for it to reach the international date line again, but this would still be just the ‘beginning’ of August 11th, it’d take another day for the ‘end’ of August 11th to reach the international date line.

  • Frank

    2 days, give or take an hour. It doesn’t matter where you live, as the celebration rule depends only on the global state.

  • Pete

    50 Hours.

    Your birth starts at midnight in the Line islands (+14 time zone) and finishes at midnight in Baker island (-12 time zone.)

  • Pete

    50 Hours.

    Your birthday starts at midnight in the Line islands (+14 time zone) and finishes at midnight in Baker island (-12 time zone.)

  • William

    It would last 47 hours, assuming 24 time zones. The last time zone would start the day 23 hours after the first and end 24 hours later.

    Taking into consideration the strange fact that there are actually 27 distinct hourly time zones, we get 26 + 24 = 50 hours.

    Either way, an hour is lost due to the offset between the first and last time zones.

  • http://www.mindyourdecisions.com/blog/ Presh Talwalkar

    Thanks all for the answers. I originally thought the answer was 48 hours: you get the 24 hours normally in a day, plus the 24 hours due to various world time zones.

    But the true answer is 50, via Wikipedia’s entry: “Because the earliest and latest time zones are 26 hours apart, any given calendar date exists at some point on the globe for 50 hours. For example, April 11 begins in time zone UTC+14 at 10:00 UTC April 10, and ends in time zone UTC−12 at 12:00 UTC April 12″

  • Kolja

    So,yeah, 48 hours.
    I didn’t really know there were time zones under -12 GMT and over +12 GMT

    And my birthday’s also 11th august !

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