La Ligne Internationale de Changement de Date (IDT) est l'une des choses les plus étranges sur la carte—ce n'est pas du tout une ligne droite ! Elle zigzague pour éviter de diviser des pays, des îles, voire même certaines communautés en jours différents, ce qui serait extrêmement déroutant. Imaginez qu'un côté de votre maison soit un jour en avance par rapport à l'autre ! Elle suit principalement la ligne de longitude 180°, mais fait de grands détours autour de lieux comme Kiribati et les Samoa afin qu'ils puissent rester à la même date que leurs voisins. Cette flexion de la ligne la rend étrange, mais elle aide les gens de ces régions à synchroniser leurs calendriers. Sans la IDT, déterminer l'heure et la date pour les voyages, l'expédition, et même pour appeler quelqu'un serait un chaos total. Animation créée par Sympa.
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Musique par Epidemic Sound https://www.epidemicsound.com
Pour ne rien perdre de Sympa, abonnez-vous!: https://goo.gl/6E4Xna
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Nos réseaux sociaux :
Facebook: https://www.facebook.com/sympasympacom/
Instagram: https://www.instagram.com/sympa.officiel/
Stock de fichiers (photos, vidéos et autres):
https://www.depositphotos.com
https://www.shutterstock.com
https://www.eastnews.ru
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Si tu en veux encore plus, fais un tour ici:
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FunTranscript
00:00Listen to this. Taylor Swift takes a plane from Los Angeles to Tokyo at 10am on February 20th.
00:08She spends 12 hours in the plane, but lands only at 2pm the next day in Tokyo.
00:14The difference is 28 hours. So, how did this temporal distortion occur?
00:19Well, it's because of this strange line.
00:21It's the date line. You know, this imaginary line that splits the globe in two
00:27and decides who should celebrate the New Year first.
00:29These are the inhabitants of the island of the line, so to speak.
00:32But by crossing this line, you will not only have the impression of entering a teleporter,
00:37it will change your day.
00:40You go from east to west, and hop, here you are 24 hours later.
00:44If you travel in the opposite direction, crossing the west line to the east,
00:49you go back a whole day.
00:52One might think that the date change line is a beautiful straight line
00:56that marks the temporal distortion in the ocean.
00:59But in reality, it's as if someone had taken a rule and said to himself,
01:04let's complicate things a bit.
01:06The line zigzags in all directions,
01:08wraps around the islands,
01:10and creates a huge confusion.
01:12For example, the islands of the Great and the Little Diomede
01:16are only 4 km apart from each other,
01:19but they have a temporal gap of 21 hours.
01:22Things can still get complicated depending on the country's time zone.
01:26For example, if you travel 1,061 km
01:30through the date change line between Baker Island and the Tokelau Islands,
01:34you have to add 25 hours.
01:36In other words, it's a day and an hour.
01:39And if that doesn't seem weird enough to you,
01:41wait a little longer.
01:42Things are getting worse.
01:44When it's 6 am on Thursday in New York,
01:46it's still Wednesday night in American Samoa.
01:49Meanwhile, in Kiribati, it's already Friday.
01:52So it's three different and simultaneous days,
01:56all because of an imaginary line.
01:58This phenomenon happens every day,
02:00between 10 am and 10.59 am.
02:05Why is the date change line so ridiculous?
02:08Good question.
02:10Although these zigzags seem totally arbitrary,
02:13they actually have a logical basis.
02:17It's actually an invented concept,
02:20based on the rotation of the planet.
02:22The Earth is constantly spinning,
02:24and it takes it about 24 hours, or a day,
02:27to make a complete rotation.
02:29To guarantee synchronization,
02:31humans divided the Earth into 24 time zones,
02:3415 degrees apart from each other.
02:36But what is the starting point of a day on Earth?
02:39In fact, it was necessary to determine
02:41which of these 24 zones, or lines,
02:44would be the starting point, or the chronological center.
02:47We needed a reference point,
02:49a line from which we could start adding,
02:52or subtracting time,
02:54when we were moving east or west.
02:57This line is what we call today the first meridian.
03:01But here's the hiccup.
03:03The choice of the location of this starting point,
03:05the first meridian,
03:07is totally arbitrary.
03:09The idea of establishing a line where the days start and end
03:12dates back to at least the 14th century.
03:14At the time, cartographers did what they wanted,
03:17choosing their own line of division east-west,
03:19called meridian.
03:21Which, by the way,
03:23is only a sophisticated Latin word for noon.
03:26In the absence of a universal norm
03:28to determine the beginning or end of a day,
03:30sailors who made long voyages
03:32had to manage on their own,
03:34trying to manage the time they gained
03:36or lost along the way.
03:38This is how, in 1884,
03:40people finally decided to organize all this mess.
03:4325 nations met
03:45at the prestigious Meridian International Conference
03:48in the United States,
03:49with a goal in mind.
03:51Decide on a line that would serve as the first official meridian.
03:54Finally, whether we like it or not,
03:56they were determined to create the date line
03:59that the whole world would accept and follow
04:01from that moment on.
04:03The first meridian was established in Greenwich,
04:05in England,
04:06and the date line was placed on the opposite side.
04:09It zigzags around the 180th meridian.
04:12It seems simple, doesn't it?
04:14But that's where the nightmare really started.
04:17The chosen date line
04:19did not settle for passing through uninhabited areas.
04:22And no,
04:23it divided some countries in two,
04:25creating a real chaos.
04:27Indeed, if you divide the world
04:29with a completely straight vertical line,
04:31you end up with situations
04:33where half of a country is ahead of one day
04:35and the other half behind one day.
04:38Take the Kiribati, for example.
04:40The country is mainly centered on the Gilbert Islands,
04:43which are just west of the date line.
04:46However, in 1979,
04:49their territory grew a little
04:51with the Phoenix Islands and the Island of the Line,
04:53located well east of the date line.
04:56Suddenly, the Kiribati found themselves
04:58on horseback on the date line.
05:01This created a number of problems
05:03for the companies.
05:04People from both sides
05:06could only communicate by radio or telephone
05:08four days a week.
05:10To remedy this strange situation,
05:12the Kiribati decided to jump
05:14on Saturday, December 31, 1994.
05:18Thus,
05:19they went from Friday, December 30, 1994
05:23to Sunday, January 1, 1995.
05:26And the new year arrived a day earlier than expected.
05:29Yippee!
05:30After that,
05:31the date line moved east
05:33to bypass the whole country.
05:35This adjustment took place in different countries.
05:37For example,
05:38when the cartographers arrived
05:40on the Aleutian Islands, in Alaska.
05:42And yes,
05:43the line had to make a new detour
05:45to encompass them.
05:46And when they arrived south of the equator,
05:48guess what?
05:49Another curve to the east
05:51in order to include other islands again.
05:53It is largely for this reason
05:55that the straight line began to zigzag.
05:57This irregular line is designed
05:59to avoid land as much as possible
06:01in order to reduce problems
06:03related to change of day.
06:04You can't find yourself on horseback
06:06on the date line
06:07and live on Monday and Tuesday simultaneously.
06:10But you can cross it by boat.
06:12In fact,
06:13some trans-pacific deluxe cruises
06:15even offer a forfeit.
06:16Time travel
06:17for adventurous travelers
06:19who want to cross the line
06:21and jump into the future.
06:23In the end,
06:24if the date line is so ridiculous,
06:27it is because it was established
06:29on the basis of a series of arbitrary decisions,
06:31of historical oddities
06:33and of a lot of confusion.
06:35But it is not because it was reorganized
06:37in the 19th century
06:39that there is no more confusion at all
06:41regarding time zones today.
06:43The first meridian also established
06:45the coordinated universal time,
06:47the famous UTC.
06:48The UTC never changes,
06:50whether for the time of summer
06:51or for any other reason.
06:53However,
06:54in 1908,
06:55Canada decided to spice things up
06:57by creating the time of summer.
06:59The idea was to advance the clocks by one hour
07:01compared to the normal time
07:03to better enjoy the light of the sun,
07:05the evenings of spring,
07:06summer and autumn.
07:08The idea was so brilliant
07:09that most countries adopted it,
07:11but not all.
07:12You just have to take Nepal.
07:14This country never used the time of summer,
07:16which means that its clocks
07:18do not change all year round.
07:19As you probably know,
07:20countries whose territory is extended
07:22often have more than one time zone.
07:24This is the case of the United States,
07:26which has 11 time zones.
07:28Australia has 9,
07:29while India,
07:30well,
07:31India is a special case.
07:33India is a large country
07:34whose territory extends
07:35over about 3,000 km west to east.
07:37It should therefore have
07:38three time zones in total,
07:40but it only has one.
07:41This means that the sun rises
07:43almost 90 minutes earlier in Dong,
07:45in the far east,
07:46than in Guarmati,
07:47in the west.
07:48Why is there only one time zone?
07:51Quite simply because
07:52they decided so.
07:53Do not forget
07:54that the timeline
07:55and the time zones
07:56are invisible,
07:57artificial,
07:58and,
07:59as you know now,
08:00totally arbitrary.
08:01Therefore,
08:02if a country wants
08:03to stick to a single time zone
08:05to simplify the processes
08:07and trade operations
08:08within its borders,
08:10why not?