In 1900, Greek divers stumbled upon a 2000-year-old shipwreck whose contents would shake our understanding of the ancient world.
Among the remains were fragments of mangled wood and corroded metal, which archaeologists soon realized contained an intricate series of gears resembling technology not believed to exist until centuries later.
By the 1950s, scientists began to understand what they'd found.
These fragments were part of a device that could calculate the movements of the Sun, Moon and planets.
Now known as the Antikythera Mechanism.
This instrument appears to be the oldest geared device ever discovered and humankind's first computer.
Most modern devices, like your phone or laptop, are examples of digital computers.
These systems store information in strings of zeros and ones that they can then convert into images on a screen or sounds in a speaker.
But more generally, a computer refers to any device that stores information and can convert it from one format into another.
And long before the rise of digital computing, human technology was dominated by analog computers.
Rather than using binary bits, analog computers receive and store signals from the real world, such as light or mechanical motion, and convert that information into something readable.
Think of how a vinyl record stores impressions of sound.
The recording device, a vinyl cutting system, writes mechanical analogs of the world.
The physical force of sound waves carves, grooves into a disc, which a record player then reads back into sound.
The Antikythera is the first known example of analog computing.
So how did it work?
Ancient Greek astronomers knew that celestial bodies zoom predictably around the solar system.
But to forecast events like solar eclipses, they'd need to perform calculations by hand.
This device likely made that process much easier.
Setting the dial to a specific day drove a series of gears to calculate that day's astronomical personality.
Metallic hands pointed to the positions of the Sun, Moon and what seemed to be the five then-known planets relative to the 12 constellations of the zodiac.
And the Antikythera's features didn't end there.
Another gear system likely spun a colored sphere representing the lunar phase.
On another phase.
One of the five dials revolved according to the Saros Cycle, the approximately 65853 days it takes for the Sun, Moon and Earth to return to their exact relative positions.
There was even a dial that indicated the timing of ancient Greek festivals.
For the Antikythera, computation lived in the connections between gears.
Each celestial body follows specific rules that govern its motion, positions and course, like changing speeds and the moon's wobbly orbit.
The fact that these ancient gears were precisely designed to compute not just one, but many of these rules simultaneously has astounded researchers.
For example, the handshake between 13 gears automatically that recreated our Moon's orbit was only seconds off from reality.
Analog computers like the Antikythera are, in fact, more efficient than digital computers.
For example, take a digital 4K movie represented by 100 billion binary digits.
These bits are fundamentally devoid of an identity.
They must be assembled by software on your TV or laptop and converted into the colors, motion and sound that simulate the real world.
While the exactness of binary code makes it reliable, digital logic requires abundance at the expense of efficiency.
And the output is always just an approximation of reality.
In contrast, consider an analog scale.
When you step on this device, the force of your body weight presses down on a spring which rotates a dial to reveal a number.
This computer converts mechanical force directly into numbers we can read.
It's a continuous input.
Weighing 150 pounds moves the spring more than weighing 149 pounds does.
And by acting continuously rather than discreetly.
Many experts argue that analog computers are more real than digital ones.
This elegance of faithfully representing real information has renewed interest in analog tech and is even inspiring new technologies.
In the future.
Analog computing may improve the efficiency of digital systems, proving what's old can be new again.
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