Earth clocks

 Title inspired by the 1988 movie Earth Girls Are Easy

A tongue in cheek assessment of timekeeping on planet Earth

by Ed Sawicki - February 2021

Our world has long-ago settled on a convoluted system of keeping time. It seems normal to us only because we grew up with it. As with many things that have evolved from concerns that have either long since been forgotten or no longer matter, we can't imagine doing it another way.

One way to see something more clearly is to imagine trying to explain it to someone who has no knowledge of it. Suppose you had to explain Earth clocks to an alien (communicating through the universal translator, of course). Our alien comes from the planet Tempor and is the female gender. You begin.

24 hours

“The time it takes for the Earth to rotate once on its axis is called a day. Each day is divided into 24 hours but we express those hours in two 12-hour parts–an AM part and a PM part. There are two of each numeric hour each day—one is the AM hour and the other is the PM hour.”

She asks, “What's the purpose of the AM and PM?”

You answer, “When we first started keeping time, some of our citizens couldn't be relied on to count beyond twelve. So, we needed two 12-hour parts to get to 24.”

She asks, “Why not make your day equal to 12 hours?”

You answer, “Our historic documents don't make that clear.”

You continue, “Each hour is divided into 60 minutes. Each min”

She interrupts, “You said some of your citizens couldn't count above 12. How do they count to sixty?”

You answer by showing her a photo of an analog clock with hands. “They don't need to know the numbers. They look at the position of the hands.” She seems satisifed with this.

Minutes and seconds

You resume, “Each hour is divided into 60 minutes. Each minute is divided into 60 seconds.”

She asks, “What if you need finer resolution than seconds? What unit divides seconds?”

“Seconds are not divided into other units. We can have fractional parts of a second.” and draw the example of 8.6 seconds on your whiteboard.

She asks, “So the .6 represents six-sixtieths of a second?”

“No, it's six-tenths of a second.”

She asks, “So your citizens are skilled at mixed number bases?”

You lie, “Yes.” realizing that you expect her to believe that citizens who can't count beyond 12 can nevertheless deal with mixed number bases.

Time zones

You continue, “Time zones divide the planet into 24 zones—one for each of the 24 hours in a day. Each of these planetary zones (nominally 15 degrees of longitude wide) has a different time than all the others.”

She asks, “What's the purpose of 24 time zones?”

Thinking quickly, you answer, “So people can eat their lunch with the sun overhead.”

“The time it takes for the Earth to revolve around our sun—We call our sun ‘The Sun’—is called a year. At a certain time of the year, we subtract one hour from our time. Some people forget and show up for appointments one-hour early. At another certain time of the year, we add that hour back, causing some people to be late for their appointments by one-hour. Some people set their clocks ahead by 5 or 10 minutes during the entire year so they're never late for appointments.”

You stop here, putting off the complexity of long-term timekeeping involving numbering days, weeks and their named days, months, years, etc. until later.

Tempor time

The alien now tells you about timekeeping on her planet, Tempor. “Each rotation of Tempor is divided into 1000 units called cads. Zero cad is when our capitol city faces our sun. 500 cad is when our capitol city faces opposite our sun. All of Tempor uses the same time—there are no zones.”

She asks, “Our timekeeping devices help us keep appointments. Why don't yours?”

At this point, you feel a little foolish, not having rational answers. You don't go into weeks, 30-day months, 31-day months, 28/29-day months, leap years, etc. for fear of sounding silly to this Temporian. Before she leaves, she mentions that her starchart doesn't have the name of Earth's moon and asks what it is. Now you're really feeling silly.

Swatch time

In 1998, the Swiss watch company Swatch introduced Swatch Internet Time, also called .beat time. It eliminated hours and minutes, replacing them with a single number between 0 and 1000 that was called the beat. It also eliminated time zones. The concept was endorsed by Nicholas Negroponte, founder and chairman of the MIT Media Lab.

Swatch beat time
Swatch showing beat time

The Swatch company knew that their new system would be met with resistance and their watches would need to display both times for many years. They built and sold watches that displayed both traditional hours and minutes as well as beat time. The photo shows a Swatch displaying the beat time as 484. It simultaneously displays conventional time as 11:37.

Each beat represents 86.4 seconds in traditional time. Midnight is expressed as @0 and noon as @500. Note the @ symbol is pronounced “at”. You might have breakfast at 350 and dinner at 750. Imagine texting your friends in faraway places, “Zoom meeting today @875” without having to specify time zones.

Beat time displayed
Linux desktops can be configured to display beat time alongside traditional time. Here, the beat time is displayed as @916.

I liked the idea and Swatch promoted it widely for a time. However, this was a step too far for most people. Although Swatch beat time disappeared in the early 2000s, there are still people who are enthusiastic over the idea. Many think that the effort stood a better chance if it were not the effort of a single company, but instead an international standards effort.

Beat time is already supported on a number of systems and languages and is simple enough to implement on systems that don't. For systems that don't directly support beat time, this C function computes it:


If Apple and Google put this in their phones, and their messaging and calendaring apps supported it, it would likely be a success in less than a generation. We might want to come up with a better name for it though.


Wikipedia: Swatch Internet Time

Wikipedia: Decimal time

Wikipedia: Sexagesimal

Wikipedia: Nicholas Negroponte

Wikipedia: Hour


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