November 12, 2020

#08-009: Global Time

Map showing modern time zones of the world

Note: Time is something that has always been around. But the way groups of humans count time has differed from place to place and, well, from time to time. This is the story of how modern global time was invented--and another invention that spurred its adoption.

Get Ready: What time zone are you in? How many hours ahead or behind Greenwich are you?

Traditional ways of telling time are based in nature. A day results from the turning of the earth, which makes it appear that the sun is going around us; a "year" results from the earth's journey around the sun, which takes approximately 365-1/4 days.

But the idea that "12:00" is the time when the sun is directly overhead, or that there are numbers to designate when it rises and sets (6 a.m., say, or 5:30 p.m.) is completely artificial. Nevertheless, this idea, too--with the numbers differing by culture--is ancient.

When travel was limited to foot or horse speed, there was no problem. But things changed when people began moving more quickly over the planet. This was aggravated by the fact that the means of such rapid travel required precise scheduling. I'm talking, of course, about the railroad.

In the late 19th century, the United States had designated 75 local time zones; three of these were in Chicago alone. Train travelers in Germany, when reading a schedule, had to be sure which of six systems--one for each of six different cities--were being used in the stated departure times.

In 1840, railway companies in Great Britain began using what was called "railway time," a single system based on clocks set to the time at Greenwich, England, home to the Royal Observatory. Starting in 1852, time checks were transmitted by telegraph all over the country. In 1880, this system was adopted for use by all citizens, not just the railways. Until then, some clocks had two minute hands: one would be set to local (solar) time, the other to "Greenwich Mean Time" (GMT).

In 1883, the United States inaugurated a system of five time zones, each one hour apart, referred to as "standard time." Some local governments, such as the city of Detroit, chose not to participate, and even switched time zones a few times, until, in 1918, the U.S. Congress passed the Standard Time Act, imposing the system on all Americans.

But before that happened, in 1884, a meeting had been held in Washington, D.C., called the "Prime Meridian Conference." At that meeting, the worldwide system devised by Sir Sandford Fleming, a Scottish-born Canadian, was adopted for use by numerous nations. It is essentially the system we have today, with 24 zones of one hour each, centered, still, on the meridian at Greenwich, designated the "Prime meridian."

Adoption was slow, but today most places use a system of time offset from Greenwich by one hour, though in some places that figure is a half-hour, and in a few, such as Nepal, a quarter-hour, to accommodate the local position of the sun.

The global day begins exactly opposite of Greenwich on the Earth's surface, at the "anti-meridian" of 180 degrees. Governments are still free to adapt the system for local needs. China, for example, spans what might have been five time zones, but has declared a single "China Standard Time" for nationwide use, eight hours ahead of UTC ("Coordinated Universal Time," the modern designation for GMT), to facilitate communication.

The continental United States maintains four time zones coast to coast, with another for the main part of Alaska and a sixth for Hawaii that also includes Alaska's Aleutian Island chain. Three further zones cover Pacific Island possessions.


Read more:

Practice: Match the term to its definition below:

  1. adopted
  2. artificial
  3. continental
  4. devised
  5. meridian
  6. observatory
  7. offset
  8. prime
  9. results (from)
  10. telegraph

  1. located on a large land mass (not an island)
  2. created; designed
  3. accepted; put into use
  4. placed in comparison
  5. a device for sending coded messages by wire
  6. manmade
  7. an imaginary line on the earth that runs from pole to pole
  8. arises as a consequence (of)
  9. first; most important
  10. a place for watching the "heavenly bodies"

Answers are in the first comment below.

Submitted to the Shenzhen Daily for November 12, 2020

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