Monday, October 18

When did all the countries of the world synchronize the clocks? | EL PAÍS Semanal: Science without fiction

A seemingly trivial question as asking what time is it? has had very complex answers at certain moments in history. The origin of dividing the hours of light and those of darkness in 12 comes from Egypt, and in turn they appropriated it from Sumeria, where they used the sexagesimal system, which is the one we still use to measure the degrees of an angle. During the day it was easy, you would put a stick on the ground and do 12 divisions. The complicated came at night. For that they used constellations, called deans, which they used to count the hours. This system had a problem. It worked very well near the equator, since days and nights have 12 hours all year round, but as you go south or north the daylight hours are longer in summer and shorter in winter. The Greek astronomer Hipparchus of Nicaea proposed dividing the day into 24 equinoctial hours, so that they would last the same throughout the year. This procedure was adopted by civilizations such as the Roman, although it was not universalized until the first mechanical clocks in the 14th century. For much of history, watches were expensive and failed a lot, so sundials were still used. This is a problem. As we move from east to west, the time changes as the sun advances, so in one town it will be one hour, but in another town located 50 kilometers to the west it will be sooner. This system in which each city had its own time was in force until the end of the 19th century.

There was an invention that forced to unify the schedules. The railway. A homogeneous rule was needed to know at what time the train arrived and left. The first to propose the international time zone system was the British railway engineer Sir Sandford Fleming in 1870. This practice was established 14 years later at the meridian conference held in Washington, in which it was agreed to take the Greenwich meridian as a reference. to set 24 different time zones. Even so, the definitive unification of hours and calendars was made at the Paris conference in 1912, where a time zone was approved every 15 degrees of longitude. In this way, Greenwich Mean Time is considered the Greenwich Mean Time (GMT), which is equivalent to Coordinated Universal Time (UTC). But, com

or in everything, there are exceptions to these spindles. With the turn of the millennium, some Pacific islands changed their time zone. They wanted to attract tourists avid to be the first to turn the millennium. China, despite extending its territory in three different time zones, has the same time for the whole country, and then there is Spain.

The unification of schedules in Spain arrived on January 1, 1901. It was established that the official time would be that of the Greenwich meridian (which passes through Xàbia and Dénia for something). And as in China today, this time was applied to the entire Spanish territory including the Canary Islands. It was not until 1922 that the Canary Islands time was delayed, which was a great success… for tourism. The famous tagline “one hour less in the Canary Islands” is the best way to get free publicity for the islands. During the Civil War, the republican zone had one hour less than the rebellion, something that was unified at the end of the war using the time of the winning side. In 1940 the time was changed again so that Spain did not follow the time that corresponds to it geographically (Greenwich, which, remember, passes through Spain), but to follow Berlin and Rome, which is known as time central European. This means that Spain has such a long day and that in winter we get up to go to work and that it is still night, especially in Galicia, where due to its geographical location it gets dark almost two hours later than it would be if it followed the solar time. The midnight sun of Betanzos in June does not have much to envy that of Trondheim. A historical accident. —Eps

JM Mulet is Professor of Biotechnology.

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