Thursday, November 02, 2006
My picture is always a bit goofy. I look too young for my age, especially when I'm all smiles. See what I mean? Sure, I'm a young and happy guy, but I still get carded in bars even though I'm 36. Sometimes my photo gives people the wrong idea of who I am and what I'm about. So I originally chose a different avatar. I have since chosen another, based on a composite photo I developed for my new website. The following is my original post explaining the thought behind my previous avatar (which I used from 2006 on and retired in 2009):
No one will get it at first, just as no one will get me at first. But once you know what it is, you'll know a lot more about me than my own picture could tell you. The image is an x-ray scan of the Antikythera Machine, the first computer ever built by man...in the 1st century B.C. Yes, you read that right. The mechanism was recovered from a Roman shipwreck near Greece, shattered, rusted, and crusted over, but has since been reconstructed using CT scans and clever reverse engineering.
What is it? An astronomical computer using a sophisticated system of exquisitely crafted gears to calculate the relative positions of the sun, moon, planets, and constellations at any time of the year, even indicating lunar phase, with a set of cranks and dials. It is not digital or electronic, but a mechanical analog computer, similar to the early targeting systems on modern battleships, but a computer all the same. Based on circumstantial evidence, it's likely this ship was carrying Roman loot from Sulla's sack of Athens in 86 B.C. It's also distinctly possible that this computer was built by the Stoic scientist Posidonius, ambassador to Rome for the island nation of Rhodes, teacher and good friend of Cicero and Pompey, and avid fan of all things Roman.
Cicero had actually seen another machine Posidonius had built, an armillary sphere, which is another mechanical computer, though instead of employing cranks and dial readouts, an armillary actually represents the sun, moon, and planets as balls on rotating rings around the central earth in three dimensions, like an actual model of the solar system. To build such a machine required estimating the relative distances of the planetary bodies, which could only be done by fanciful conjecture for the planets, but was more or less within the means of the time to calculate for the sun and moon.
It was probably to that end that Posidonius employed astronomical science to calculate those distances. Using geometry and astronomical data he estimated the sun to be roughly 57 million miles from the earth, a figure more than half the true distance, far more accurate than any other astronomer’s estimate in antiquity. He also calculated the sun was about 343,000 miles in diameter, which is nearly half the true solar diameter of 870,000 miles, a value also unrivaled until modern times. Posidonius’ calculation of the moon's distance came to roughly 229,000 miles, which is essentially correct. And he worked out that the circumference of the earth fell between 27,500 and 20,500 miles, for an average of about 24,000 miles, which is very close the correct value of about 25,000 miles. These are incredible achievements, and would not be improved upon until more modern times.
Besides astronomy (including confirming that the tides correlated with the position of the moon), Posidonius also wrote treatises on mechanics later employed by engineers like Hero of Alexandria. So building the Antikythera Mechanism would be a dawdle for a genius like Posidonius. At any rate, he's the number one suspect in its construction. A simple version of the machine is shown here to the right, although the actual machine had dials and readouts on both the front and back, and a considerable number of marks and words engraved.
There is a sad ending to the story. Though Posidonius (shown at left) wrote extensively on science, history, tactics, engineering, ethnology, and philosophy, Christian scribes chose not to preserve a single book or even a single page of his work. All we know about what he wrote and did comes from scattered quotes and paraphrases by later authors, even though Posidonius was widely regarded in his own day, and still by knowing scholars now, as one of the greatest scientists and most influential philosophers of the Roman era. I can't tell you how often I run into this tragic loss in my study of the ancient world. Medieval Christians genuinely deserve condemnation for tossing great work like this in the garbage and instead exhausting their resources on copying tons of inane religious literature. But that's a soap box for another time.
Back to the point. Why use an x-ray of the Antikythera computer as my avatar? For many reasons. In the least important sense, it is a metaphor for the many great achievements of the Greeks and Romans drowned into oblivion under the tenure of the Christian Church. Though this shipwreck has nothing to do with that, the fact that no writings about this machine were preserved, nor anything written by Posidonius, has a lot to do with it. Hence the fact that we have to peer into the muck and crust with x-ray machines to discover the truth of our pre-Christian past is somewhat symbolic of the dangers of religious zealotry.
But more importantly, I chose this because it is an astonishing symbol of the incredible genius of humankind, a pursuit of reason and excellence that I fight for and embrace. Not only is the machine itself fantastically ingenious, but so is the work done by modern engineers to reconstruct and recover its technology from scattered and ruined scraps. The very invention of the x-ray camera, and then its improvement to generate computerized axial tomography (used now on the Antikythera debris), is yet another symbol of humanity's admirable achievements. This is what I am about. Technology, ingenuity, explanation and mastery of the world through reason.
Yet more because the Antikythera Machine represents the amazing scientific, astronomical, and technological achievements of the Greeks and Romans in particular, which have all captured my mind and my career. I am continuously amazed at what I learn, not only about what the ancients achieved and knew, but also how difficult and complex the questions they answered were. They ventured smartly into planetary theory, the laws of mechanics, optics, and acoustics, even neurophysiology. And though never mass produced or ubiquitously available, they nevertheless had all manner of technologies, from vending machines and mechanized harvesters to automatic doors and electroshock therapy. The Antikythera computer is perhaps the most amazing of all. If you want to know what fascinates me, this is it.
But even more I chose it because this discovery shattered all the assumptions of historians of science about the cultural and social context of ancient science and technology, refuting in one blow a widespread belief that ancient scientists did not work closely with ancient craftsmen, or endeavor to achieve technological advances, or respect any physical work of the hands. It reminds me of how easily historians can get things wrong, and how important careful historical methodology is. This find is an especially good example of how the archaeological record repeatedly proves there were things going on in the ancient world that our surviving literary texts don't mention, demonstrating the dangers of arguments from silence, which have been all too common in the history of science. Careful historical methodology, getting right the history of ancient science, these are things I am very much about.
But above all, I chose it because this picture represents my interests as a historian: ancient science and intellectual achievements, especially in the Roman era; and also my interests as a philosopher: science, mechanism, and the empirical application of reason. As I think of myself as both a historian and philosopher, a symbol that captures both sides of my intellectual life seems fitting. And if all that fails, my x-ray avatar looks creepy, weird, and ghostly enough to freak out the squares and pain the brains of the low foreheads. And I'm definitely all about that.
My next book, which should be out in a few years, will have a lot more to say about ancient science (including Posidonius and the Antikythera Machine). But tomorrow I'll post something on the subject that has come up recently on the internet.