Thread by @ESpacewalk

Wanna blow your mind?! 🤯

An Ancient Greek Astronomical Calculation Machine Reveals New Secrets via @uclmecheng in @sciam

"Scientists have a new understanding of the mysterious #AntikytheraMechanism that challenges assumptions about ancient technology"

scientificamerican.com/article/an-anc…

@uclmecheng @sciam "One object recovered from the site, a lump the size of a large dictionary, initially escaped notice amid more exciting finds. Months later, however, at the National Archaeological Museum in Athens, the lump broke apart, revealing bronze precision gearwheels the size of coins.

@uclmecheng @sciam According to historical knowledge at the time, gears like these should not have appeared in ancient Greece, or anywhere else in the world, until many centuries after the shipwreck. The find generated huge controversy.

The lump is known as the Antikythera mechanism, an

@uclmecheng @sciam extraordinary object that has befuddled historians and scientists for more than 120 years. Over the decades the original mass split into 82 fragments, leaving a fiendishly difficult jigsaw puzzle for researchers to put back together. The device appears to be a geared

@uclmecheng @sciam astronomical calculation machine of immense complexity. Today we have a reasonable grasp of some of its workings, but there are still unsolved mysteries. We know it is at least as old as the shipwreck it was found in, which has been dated to between 60 and 70 B.C.E., but other

@uclmecheng @sciam evidence suggests it may have been made around 200 B.C.E...

In modern terms, all the moving astronomical bodies have orbits close to the plane of Earth’s motion around the sun—the so-called ecliptic—meaning that they all follow much the same path through the stars.

@uclmecheng @sciam Predicting the positions of the planets along the ecliptic was very difficult for early astronomers. This task, it turns out, was one of the primary functions of the Antikythera mechanism.

@uclmecheng @sciam Another function was to track the positions of the sun and moon, which also have variable motions against the stars.

Much of the mechanism’s design relies on wisdom from earlier Middle Eastern scientists.

@uclmecheng @sciam Astronomy in particular went through a transformation during the first millennium B.C.E. in Babylon and Uruk (both in modern-day Iraq).

@uclmecheng @sciam The Babylonians recorded the daily positions of the astronomical bodies on clay tablets, which revealed that the sun, moon and planets moved in repeating cycles—a fact that was critical for making predictions.

@uclmecheng @sciam The moon, for instance, goes through 254 cycles against the backdrop of the stars every 19 years—an example of a so-called period relation. The Antikythera mechanism’s design uses several of the Babylonian period relations...

@uclmecheng @sciam It took months to understand these gears. When I did, the results were astonishing. These gears turned out to calculate the variable motion of the moon in a very beautiful way.

@uclmecheng @sciam In modern terms, the moon has variable motion because it has an elliptical orbit: when it is farther from Earth, it moves more slowly against the stars; when it is closer, it moves more quickly.

@uclmecheng @sciam The moon’s orbit, however, is not fixed in space: the whole orbit rotates in a period of just under nine years.

@uclmecheng @sciam The ancient Greeks did not know about elliptical orbits, but they explained the moon’s subtle motion by combining two circular motions in what is called an epicyclic theory...

The device is unique among discoveries from its time.

@uclmecheng @sciam It single-handedly rewrites our knowledge of the technology of the ancient Greeks. We knew they were highly capable—they built the Parthenon and the Lighthouse of Alexandria even earlier than the Antikythera mechanism. They had plumbing and used steam to operate equipment.

@uclmecheng @sciam But before the discovery of the Antikythera mechanism, ancient Greek gears were thought to be restricted to crude wheels in windmills and water mills.

@uclmecheng @sciam Aside from this discovery, the first precision-geared mechanism known is a relatively simple—yet impressive for the time—geared sundial and calendar of Byzantine origin dating to about C.E. 600.

@uclmecheng @sciam It was not until the 14th century that scientists created the first sophisticated astronomical clocks. The Antikythera mechanism, with its precision gears bearing teeth about a millimeter long, is completely unlike anything else from the ancient world.

@uclmecheng @sciam Why did it take centuries for scientists to reinvent anything as sophisticated as the Antikythera device, and why haven’t archaeologists uncovered more such mechanisms?

@uclmecheng @sciam We have strong reasons to believe this object can’t have been the only model of its kind—there must have been precursors to its development.

@uclmecheng @sciam But bronze was a very valuable metal, and when an object like this stopped working, it probably would have been melted down for its materials. Shipwrecks may be the best prospects for finding more of them.

@uclmecheng @sciam As for why the technology was seemingly lost for so long before being redeveloped, who knows? There are many gaps in the historical record, and future discoveries may well surprise us.

With the Antikythera mechanism, we are clearly not at the end of our story.

@uclmecheng @sciam We believe our work is a significant advance, but there are still mysteries to be solved. The UCL Antikythera Research Team is not certain that our reconstruction is entirely correct because of the huge loss of evidence. It is very hard to match all of the surviving information.

@uclmecheng @sciam Regardless, we can now see more clearly than ever what a towering achievement this object represents."

CC: @wrathofgnon @SamoBurja @indyfromspace