Standard Time And The Day Of Two Noons

Time can be too accurate or not accurate enough, but it is rarely right.

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Many of you know that I have a kind of fascination with dates, times and the way they have changed over time. Everyone measured time by using the sun 150 years ago, and while this may not have been highly accurate – well, who cared? Farmers got up when the sun rose and did their stuff until the sun set. Most people had no need for time and the idea of a watch would have been..well…untimely.

As has happened so many times in history, when communications changes it creates paradigm shifts that ripple through society. Back 150 years, it was the coming of the steam engine and rail transportation that brought about a revolution. It all started in England, back in 1828, when Sir John Herschel started to lobby for the notion of a standard time. Nobody really took him seriously.

Then in November 1840, the Great Western Railway in England, built by the greatest engineer of the time, Isambard Kingdom Brunel, decided to synchronize local times and a single standard time was instituted. This was because it was too difficult to build timetables when trains could sometimes arrive at one station before they had left the previous one. Riders were never quite certain when the train would arrive, and the about the only places that had a clock were the stations themselves.

It took a while before the other lines in England adopted similar policies, first with each company creating their own standard time. Within three years, they were all synchronized to Greenwich Mean Time (GMT).

By 1855, time signals from Greenwich were sent through wires alongside the railways, meaning that all stations were synchronized automatically. In 1880, a unified standard time for the whole of Great Britain achieved legal status.

In took the United States until 1869 to act. Charles F. Dowd, principal of Temple Grove Ladies’ Seminary at Saratoga Springs, N.Y., pushed the case for four time zones, separated by 15 degrees of longitude. Professor Benjamin Pierce of Harvard picked up the baton in the 1870s.

Again, it came down to the railroads, and William F. Allen championed the cause and brought together the General Time Convention, a group formed to coordinate their schedules. They all came to agreement in 1883 to designate five time zones. In the early days, the line was not drawn exactly along state lines or even the correct degrees of latitude, instead taking a fairly wiggly path associated with railroad terminuses.

The big date was Nov. 18, 1883, and the general populace was not quite sure what to make of this. Just as with the shift from the Julian to the Gregorian calendar, where people thought that days were being stolen from them, they had no idea what to think about time changing. Would they be frozen, would the world come to an end?

It was known as the day of two noons. People were required to stop what they were doing and reset their clocks anywhere from two to thirty minutes. The New York Times reported, “There was a universal expression of disgust when it was discovered that all that was necessary to effect the change was to stop the clock for four minutes and then start it again.”

It worked for the railroads, but still the rest of the country was less than eager to have their times synchronized. Legal challenges were raised, and in 1915 a time standard was still being considered by the courts. Chicago authorities refused to adopt the standard time and it is argued that this is because the Chicago meridian was not selected as the one on which all time must be based. In 1918, Congress officially adopted the railroad time zones and put them under the supervision of the Interstate Commerce Commission.

As technology and communications in particular have improved, the need for finer synchronization of time has become important. Throw out the first generation of atomic clocks that measured the natural vibration of a cesium atom. Today’s clocks have an uncertainty of 2.3 x 10^−16, meaning they would neither gain nor lose one second in about 300 million years. Perhaps that is more accurate than we can make use of in our daily lives, but GPS relies on accuracies of 50 nanoseconds in order to function correctly. Errors in time become errors in placement.

Despite the incredible accuracy of that clock, even better ones are being developed, but they are so accurate that they actually create a problem. Time, as Einstein himself discovered, is dependent on gravity, and so time is only accurate to those standing at the same height and assuming constant gravity.

So on Nov. 18, it is perhaps worth pausing for a few minutes, just as they did 150 years ago, to think about the importance of time and how it has transformed our lives.


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  • Paul Brunemeier

    Interesting story, Brian, thank you. Optical lattice clocks are now stable to about 1 sec in 5 billion years, roughly the age of the earth. This is more that a factor of thirty better than existing single-atom clocks that I think you reference.

  • Rob Neff

    As a hobby genealogist and a full-time engineer, I also have been interested in times and dates, and how some things we take as constants are surprisingly arbitrary. For example, when converting to metric, the French briefly tried to adopt metric time, with 10 hours per day and 100 minutes per hour. What will Martian colonists do with a day that is 37 minutes longer than an Earth day, and a year that is about twice as long? When do you celebrate your birthday?

    More practically, I hear a lot of people calling for the end of daylight savings. I wonder how easily that could be done with all the software that is out there now, would we have another pseudo-eventful Y2K problem if we were to go off the DST system?