Building a Solar Metric Clock: Mike Olson on Decimal Time and "True" Noon
The Long Now Foundation
In this five-minute Ignite talk for the Long Now Foundation, Mike Olson asks why time is the one everyday measurement that never went metric. They describe building a working decimal clock that also tracks solar time, and then turning it into a free iPhone app.
Why Time Is "a Hot Mess"
Olson starts with an oddity. Length and volume have both customary and metric units, like feet and meters or quarts and liters, but time only has seconds, minutes, and hours. Those units don't come in tens. Olson credits the twelve-hour division to the Babylonians, who could count to twelve on one hand, and says this is why the day has 24 hours.
The words "minute" and "second" are also old. Olson traces them to Latin: the first small division of the hour and the second small division of the hour. Minutes and seconds come in sixties, a number Olson attributes to the Assyrians, "possibly by way of the Akkadians," while adding that "we don't really know." The result is 60 seconds to a minute, 60 minutes to an hour, 24 hours to a day, and 86,400 seconds in a day. Olson calls this "a hot mess" because you can't do mental arithmetic with numbers like that. A simple base-10 system, they argue, would be much easier.
Olson notes they aren't the first to think of this. The French Revolution tried, at least in part, to replace the 24-hour clock with a ten-hour day of 100-minute hours. Olson calls it a great idea that "just didn't last that long."
How Metric Time Works on Olson's Clock
Olson decided to build a metric clock. Keeping metric time means tracking decidays, centidays, millidays, and units of 100 microdays. Olson calls the last one a "mic," which is 8.64 seconds long. A metric day starts at 0000 and runs to 9999. To show how the numbers map to familiar times, Olson points out that 1:00 a.m. is roughly 0420.
The first version was built from assorted electronic components and an Arduino. Olson shows a photo taken at 8802 on the evening they finished it. The clock gets the correct time from a component that communicates with the GPS satellite network.
From "Correct" Time to Solar Time
The GPS component led Olson to question what "correct time" means. They argue that official time is "imposed on us by the man." It depends on your time zone and on whether daylight saving time is in effect. Olson shows a time zone map and calls it "a geopolitical legislative disaster."
So Olson decided to track a second kind of time as well: true time based on where the sun is in the sky. The sun reaches its highest point at noon, and that moment shifts as you move east or west in longitude. Olson explains that it's more complicated than that, because Earth's orbit is an ellipse rather than a circle. The angle between an observer and the sun changes slightly every day, so solar noon moves "just a scooch" daily.
The gap between clock time and sundial time is called the equation of time. Olson shows its curve over a year and calls it "an ugly curve." They found a good approximation online, turned it into code, and added it to the metric clock. The result was a solar metric clock.
Prototypes and a Desk Clock
With more components, Olson built and tested a second prototype. A photo from one day shows 6175 in solar metric time and 6246 in civil metric time. Olson stresses that this offset applied on that day at their house, and it changes slightly every day. After soldering the components and 3D-printing a case, Olson had a finished desk clock.
Living on Metric Time
Olson describes what keeping metric time is like day to day. They wake up before 2500 every day. For them, 9000 isn't late, but 9500 "is getting up there." They schedule in units of 100 mics, which they describe as just under 14 minutes and a good minimum scheduling unit. Olson also likes that the numbers show how much of the day has passed: 3900 means 39% of the day is over. They call this "an interesting way to position yourself in time."
Multiclock: Taking It to the iPhone
Olson wanted to share the clock widely, but the hardware versions are hard to build. So they taught themselves Swift, learned iOS interface design and abstractions, and built an app called Multiclock. It has been on the App Store for a while and can be found by searching "multiclock civil solar metric." Olson says it collects no data, costs nothing, and has all its code on their GitHub.
Olson closes with one last conversion: anyone running the app would know that an Ignite talk lasts "just over 35 mics."
It is weird if you think about it that there's no metric system for time. We got feet and meters, we got quarts and liters, but for time we got seconds, minutes and hours. And hours come in 12, not tens. 12, by the way, a gift from the Babylonians, who could count to 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 on one hand, and therefore 24 hours in the day.
Seconds likewise ancient. We get the names minute and second from ancient Latin: pars minuta prima, the first small division; pars minuta secunda, the second small division of the hour. Minute, small; second, second small. Okay.
Seconds and minutes of course come in 60s, that number a gift from the Assyrians, possibly by way of the Akkadians, we don't really know. But 60 seconds in a minute, 60 minutes in an hour, 24 hours in a day, 86,400 seconds in a day. Guys, it's a hot mess. You can't do math in your head on numbers like that. It'd be way easier if there were a simple base 10 metric system for time.
Now, I'm not the first guy to think about this. The French actually had a revolution aimed at least in part at replacing the 24-hour clock with a 10-hour day of 100-minute hours. Great idea, off to a good start, as you remember from history class, just didn't last that long. But a good idea. I decided I wanted to work on that idea. I decided that I wanted to build a metric clock.
If you're going to keep metric time, you have to track decidays and centidays and millidays and 100 microdays. A mic is 8.64 seconds long. A metric day starts at 0000, goes to 9999. This number, 420, yeah, that's what you call 1:00 a.m.
I got a bunch of components and an Arduino. I wired it up, and you can see I took this picture at 8802 on the evening that I finished building the clock. The clock, by the way, knows what time it is because up in the corner there's a component that talks to the GPS satellite network to get the correct time. And that started me thinking about correct time.
You guys, the correct time is imposed on us by the man. It depends on what time zone you're in and whether daylight saving time is in effect. This map is a geopolitical legislative disaster. So I decided maybe I'd also track another kind of time, the true time, based on the position of the sun in the sky.
The sun's at its highest point at noon, of course, and that depends on where you are in the earth. If you move west or east in longitude, noon moves as well. But it's more complicated than that, because the Earth's orbit around the Sun is an ellipse, not a circle. So every single day the angle between you and the sun changes just a scooch. Noon moves just a scooch.
The difference between the clock and the sundial is called the equation of time, and this curve shows you the equation of time over the course of the year. It's an ugly curve. It turns out that there's a good approximation that you can find on the internet. I grabbed it, I rendered it into code, and I added it to my metric clock, and I had a solar metric clock.
I got some more components, I built another prototype and got it working as well. You can see in the picture that on the day that I took this picture, 6175 solar was 6246 civil metric. Now, that's on that day at my house; it changes a scooch every day. But I soldered these components up, I 3D printed a case, and I had a nice desk clock.
When I'm keeping metric time, I wake up before 2500 every single day. 9,000 is not that late, but 9500 is getting up there for me. I schedule things in 100-mic units; that's just under 14 minutes, a good minimum scheduling unit for me. And 3900 is 39% of the way through the day. It's an interesting way to position yourself in time.
I wanted to share this with a lot of people, but these are hard to build. So I taught myself a new programming language, Swift. I learned some iOS UX, interfaces and abstractions, and I built an application called MultiClock. This clock has been uploaded to the App Store; it's been up there for a while. You can search for MultiClock civil solar metric and get it on your iPhone. Collects no data, costs no money, all the code is up on my GitHub. And if you had the app on your clock, you'd know that an Ignite talk is just over 35 mics.
[Applause]
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