The History of Timekeeping

For most of human history, time was fluid. Communities relied on the sun, setting the town clock to noon when the sun reached its highest point in the sky. This meant that noon in Washington D.C. was completely different from noon in New York City. For centuries, this wasn't a problem—until we started moving faster than a horse.

The Railway Revolution

The invention of the steam locomotive in the 19th century threw local time into chaos. A train traveling across the United States would pass through dozens of different local time zones. Scheduling became a mathematical nightmare, and worse, a safety hazard. Trains sharing the same track but operating on different local times were at constant risk of collision.

The Birth of Standard Time

To solve this, railway companies in North America instituted "Standard Railway Time" in 1883, dividing the continent into four distinct zones. It was so successful that the following year, the International Meridian Conference was held in Washington, D.C. Representatives from 25 nations agreed to divide the entire globe into 24 time zones, establishing the Prime Meridian in Greenwich, England, as the ultimate zero-point.

The Atomic Age

Today, we no longer rely purely on the rotation of the Earth to measure a second. Since 1967, the official definition of a second has been based on the vibration of a cesium atom. These "Atomic Clocks" are so incredibly precise that they will not lose or gain a second for over a hundred million years.