With a watch on our wrist and a cell phone with us 24/7, time is a concept we take for granted and seem to question only when changing to and from Daylight Saving Time. Until relatively recently, this idea of time as we know it was foreign to most humans. Through most of history humans were too busy staying alive to think about regimented time.
If you lived in the Middle Ages your day would most likely have been regimented by sunrise, noon, sunset and bedtime. Centuries after the invention of mechanical clocks in the mid 14th century, most people couldn’t afford them. Roosters, the sun, servants, the town crier, church bells, and factory whistles were all more likely to wake up the average person than the chime of a clock, or an alarm clock. But just as some of us don’t need an alarm to wake up every morning, people would have had the same ‘biological clock’, or circadian rhythms, that we do today.
Even with the proliferation of clocks and watches (which were invented in the early 16th century and later helped fuel the efficiency and regimentation of the Industrial Revolution) localities set their own solar time. There were many variations in time, but without universal communication and high-speed transportation, those variations were not widely noticed.
With the advent of the telegraph and the railroads, these discrepancies became big problems. Every city in the United States used a different time standard so there were more than 300 local sun times to choose from. Each train station set its own clock making it difficult to coordinate train schedules. Time calculation became a serious problem for people traveling by train (sometimes hundreds of miles in a day). The train operator had to reset his watch at each station in an effort to determine the departure time. It was a nightmare for the railroads to try to coordinate complex interdependent schedules for coast-to-coast rail travel without confusing passengers and operators alike.
In 1879, the US Weather Service chief Cleveland Abbe introduced four standard time zones for his US weather stations. Operators of the new railroad lines needed a new time plan that would allow a uniform train schedule for departures and arrivals. Abbe offered his time system to the railroads and encouraged them to adopt it. The railroads introduced Abbe’s four standard time zones for the continental United States at noon on November 18, 1883, when the telegraph lines transmitted time signals to all major cities.
On November 1, 1884, the Greenwich Meridian was adopted universally at the International Meridian Conference in Washington DC. As a result, Greenwich Mean Time (solar time at the Greenwich Observatory, Greenwich, London) became the time standard and 24 worldwide time zones were created.
Greenwich Mean Time was replaced as the international time standard in 1972 by UTC (Universal Coordinated Time) which uses the IERS Reference Meridian (IRM), International Reference Meridian, as the prime meridian (slightly different than the Greenwich Prime).
Today, the International Atomic Time, kept by 300 atomic clocks around the world, keeps earth’s time to within microseconds of accuracy of solar time.
Most of our cell phones are defaulted to update the time as it changes automatically. If you travel from one time zone to the next, your phone is supposed to update after you’ve “checked in” with the local cell towers. The cell towers tie into the GPS satellite system or GPS sync time server on-site at the tower.
If something happened to our electronics or our ability to charge them, how well would we handle the elementary times of sunrise, noon, sunset and bedtime?