This year at TED Global 2009, I delivered a nine-minute TED U presentation called “The Astrolabe: Using the World’s First Computer.” For this presentation, the Oxford Science Museum kindly lent a beautiful replica of Seventeenth Century European Astrolabe with which I could demonstrate how an eleven year-old boy could tell the time in the Fourteenth Century.
The point of the presentation was to illustrate that as technology advances, we gain some things and lose other things.
Here is an excerpt of the presentation.
As technology progresses, many of us assume these advances make us smarter and more connected to the world. But I’d like to suggest that’s not completely true. Progress is really just an optimistic word for change. And with every change you gain something, but you also lose something. To illustrate this point, I’d like to show you how technology has dealt with a very basic question: what time is it?
Well, that’s easy, isn’t it? We simply glance at our iPod or Blackberry. But imagine we are just outside this theatre at the founding of Oxford University some 600 years ago. How would we tell time then?
We would use this - an Astrolabe. The Astrolabe is almost unheard of today, but in the 14th century it was the gadget of it’s day - the western world’s first practical computer. The Astrolabe is an interactive model of the sky that plots the sun and stars as they move across the heavens. From India to Spain and from Africa to England, it was used not just for timekeeping, but for navigation and surveying. It could perform hundreds of complex calculations.
Astrolabes are constructed of a half dozen brass parts. The largest is called the Mater. The cut-out mesh is called the Rete, and the circular disks are called plates. Each of these parts has their own function. The device was so useful, that every educated child was expected to know not only how to use one, but also how to make one.
We know this because the first English manual of the Astrolabe was written by Chaucer in 1391 - yes, the Chaucer - for Little Lewis, his eleven year old son.
3. The Big Idea
In the Treatise, Lewis learned the big ideas of the device: how to represent the three-dimensional sky that surrounds us onto a flat two-dimensional surface using Stereographic Projection. This technique depicts the sky as a giant sphere with the earth at the center. Every point on the sphere is projected through a pole to a flat surface and recorded. This process accurately maps celestial objects to the Astrolabe preserving important geometric properties. The north star (or more accurately, the North Celestial Pole), corresponds to the center of the Astrolabe. Prominent bright stars, such as Deneb are represented by little pointers on the Rete. The Ecliptic, the path of the sun, moon and planets corresponds to a circle on the Rete. The position of any star can be accurately mapped onto the Rete relative to other stars. The local horizon, what the sky looks like from any particular place on the earth, is represented as a kind of off-center spider web.
So the Astrolabe is a map of the heavens. The real genius of the astrolabe is that it showed two coordinate systems at the same time. It brought together the coordinates of the local geographic sky with the celestial sky.
4. The Real Astrolabe
So how do you tell the time? This is an Astrolabe. Its a replica of a 15th century device and its on loan from the Oxford Science Museum, just 5 minute walk for here and home to about 150 Astrolabes, over a tenth of the world’s public collection. I’ve always wanted a real astrolabe, but a real one would cost more than my house, and all the houses on my block put together, on both sides of the street. So I haven’t acquired on yet. You can see this Astrolabe is relatively small, about 4 inches in diameter. And was intended to be a functional device, as opposed to a showpiece.
This is the Mater. This is the Rete. Here, the little daggers that represent the positions of stars. Between the Rete and the Mater are the Plates with their spiderweb patterns of altitude and azimuth set for Oxford’s latitude. (you have not yet explained azimuth) On the back is a sighting device called the Alidade.
Say we wanted to know the time this evening.
Step One: We would select a bright star. We could choose the Deneb, a member of the summer triangle.
Step Two: Use the alidade to measure the Deneb’s altitude - its apparent angular elevation above the horizon. I can sight Deneb and then use a scale on the back of the mater to see that the star is about 40 degrees above the horizon.
Step Three:Find Deneb on the Rete
Step Four: Rotate the Rete so that the Deneb marker points to the right altitude on the plate. When lined up, we have an accurate map of the heavens. In the palm of my hand, this intricate piece of brass corresponds rather perfectly with the sky.
Step Five: To tell the time, I draw a line along calendar scale to a time marker. And voila - it’s 10:15 pm, when Deneb is 40 degrees above the horizon.
Now, I know what you’re thinking….that’s lot of work just to find out what time it is. And if you’re thinking about glancing at your iPhone in that abstracted way we usually do, then you may have a point. Let me assure you, habitual use of the astrolabe is not at all tedious.
In fact, what little Lewis had right in his hand was not just chronological time as we now think of it but time relative to space and space to time. And by holding such a device in his hand and knowing how to use it, Lewis had a deep sense of orientation and connection with the universe and his place in it and in time. He knew where true North and the cardinal directions were, where the sun would rise and set and when it would rise and set.
In computer user interface design, there is a concept called affordances - the quality of an object that allows a person to perform an action. The astrolabe affords us a deep knowledge of both the seen and unseen. I’m sure to Lewis, this felt like pure magic. And I suspect he had a profoundly different relationship with the sky than today’s eleven year-olds.
6. Other Uses
So this is just the start. We’ve only looked at one side of the Astrolabe. The flip side has scales and markings for all kinds of other uses. Each culture that discovered the device modified it and extended it to solve specific problems. For example, Arabic and Persian Astrolabes had markings to indicate the five prayer times of Islam. European Astrolabes had markings to tell the eight Christian prayer times. Most had tools for making terrestrial measurements. In fact, the majority of medieval cities were surveyed with Astrolabes. In addition to be useful instruments, they were, quite simply, beautiful.
The quality of workmanship was outstanding. No CAD tools were available to produce these devices. Only skilled hand labour and a keen eye. The complex patterns on the plate could be created by a compass and straight edge using instructions that Little Lewis could understand. The Astrolabe that I’ve described is based on earlier Greek instruments, such as the Antikythera, which is over 2000 years old. There were Astrolabes made of paper which were probably the most common. At the Oxford Science Museum, you’ll see Astrolabes made of Wood.
8. The March of Technology
I hope that by understanding this device you can see that our forebearers were remarkably resourceful. Casting two big ideas into brass, they created a product line that lasted almost two thousand years and penetrated every market. But time progresses, and as always, new disruptive technologies - like the clock and the digital computer - overtake and displace old technologies, rendering them obsolete.
What the new technologies offer is incredibly compelling. But what we might lose is subtle yet valuable – like a direct felt understanding of how things work, and the connection of that understanding as the most integral aspect of the device itself. Knowing the sky and your place in relationship to it was the very center of knowing the true answer to that seemingly simple question: What time is it?
With new affordances, putting our attention to only some things slowly erodes our awareness of what’s immediately in front of us. And perhaps with it, a kind of intelligence. Who decides what knowledge gets lost along our forward march and at what cost?
Does it matter if we understand how the sky works, or if we can point to the North Star or if we spend more of our time in the abstract world? Pushed through the filter of technology, perhaps this is the kind of knowledge that first becomes forgotten, then invisible and eventually extinct. Devices like the astrolabe teach us that we are capable of merging a couple of really smart ideas into genius and that genius can not only keep alive what is immediately in front of us but also that which we cannot see yet has a profound significance to our place in the universe and ours to it.