Unwrapping The Herculaneum Papyri With Infrared, Imaging, And AI

By John Oncea, Editor

The Herculaneum Papyri, buried by Vesuvius in 79 BCE, are being deciphered using advanced imaging and AI, revealing ancient texts on philosophy and pleasure.

My daughter went to Italy a couple of summers ago and more or less fell in love with the country. She loved the food, would spend much of the rest of her life on the Amalfi Coast, was enthralled by the Colosseum, and thought the Vatican was all right but “wouldn’t go back.”

She also visited Pompeii, a city in southern Italy’s Campania region that “was founded in 600 BCE and eventually grew from its Greek and Etruscan roots into a bustling Roman trading city and port,” according to Rick Steves’ Europe. “Neither rich nor poor, Pompeii was a typical middle-class town. To serve its 20,000 residents, the city boasted more than 40 bakeries, 130 bars, and plenty of public baths.

“Being a port, it also had brothels, restaurants, and entertainment venues that catered to sailors from all over the Roman world — many of whom didn't speak a lick of Latin. Most of Pompeii's buildings were covered in brilliant white ground-marble stucco, making it an impressive sight. And from its richly decorated forum, people had a postcard-perfect view of the looming volcano, Mount Vesuvius.”

Cue the ominous music.

Mount Vesuvius erupted in 1944. And in 1929, 1906, 1872, 1868, 1861, 1855, 1850 … the list goes on. All total, Vesuvius erupted 21 times between 1660 and 1944 alone. According to Britannica, “A major eruption that took place on December 16, 1631. Many villages on the slopes of the volcano were destroyed, about 3,000 people were killed, the lava flow reached the sea, and the skies were darkened for days.”

But it’s the great eruption of 79 BCE that Vesuvius is most commonly known for. That eruption, after centuries of dormancy, buried the cities of Pompeii, Oplontis, and Stabiae under ashes and lapilli under a mudflow. History adds, “According to Pliny the Younger’s account, the eruption lasted 18 hours. Pompeii was buried under 14 to 17 feet of ash and pumice, and the nearby seacoast was drastically changed.”

In addition, the city of Herculaneum was buried under more than 60 feet of mud and volcanic material. “A westerly wind protected Herculaneum from the initial stage of the eruption, but then a giant cloud of hot ash and gas surged down the western flank of Vesuvius, engulfing the city and burning or asphyxiating all who remained,” writes History. “This lethal cloud was followed by a flood of volcanic mud and rock, burying the city.”

Buried along with the rest of the city were what are today called the Herculaneum scrolls. These scrolls offer a direct window into the ancient world, untainted by later interpretations or transcription errors. This collection represents the largest known intact library from antiquity. The prospect of reading these texts promises unprecedented insights into classical literature, philosophy, and knowledge but for centuries it has been impossible to read them.

All that recently changed thanks to virtual unwrapping software and machine-learning algorithms.

Recovering The Remains Of Herculaneum

According to Smithsonian Magazine, “In the 18th century, workmen employed by King Charles III of Spain, then in charge of much of southern Italy, discovered the remains of a magnificent villa, thought to have belonged to Lucius Calpurnius Piso Caesoninus (known as Piso), a wealthy statesman and the father-in-law of Julius Caesar. The luxurious residence had elaborate gardens surrounded by colonnaded walkways and was filled with beautiful mosaics, frescoes, and sculptures. And in what was to become one of the most frustrating archaeological discoveries ever, the workmen also found approximately 2,000 papyrus scrolls.”

The Herculaneum scrolls represent an unparalleled treasure trove of ancient knowledge – the only intact library known from the classical world. Unlike most surviving classical texts, which underwent centuries of copying and potential alteration by scribes, these works are direct artifacts from Greek and Roman scholars. However, Mount Vesuvius’ eruption and the ensuing smothering of Herculaneum carbonized the scrolls, transforming them into brittle, coal-like cylinders.

Past attempts to unroll and read the scrolls often resulted in their destruction, reducing many to fragile flakes that yielded only fragments of text. This led to hundreds of papyri remaining unopened, their contents seemingly lost to time.

Ironically, the catastrophic heat that carbonized the scrolls also ensured their survival by eliminating moisture, which would have otherwise caused decay over the millennia. This presented both an opportunity and a challenge for scholars seeking to unlock their secrets, a challenge the University of Kentucky’s Brent Seales accepted back in 2008.

There’s Lead In Them There Scrolls

“The Herculaneum Papyri are among the most iconic — and inaccessible — items in the ‘invisible library’ of irreparably damaged manuscripts,” writes Pigman College of Engineering. “Since the scrolls’ discovery, people have tried various physical efforts to ferret out their contents. The results were largely disastrous. The most successful attempts were made in the 19th century when about 300 of them were peeled apart by machines. This endeavor resulted in fragmented, layered sheets of brittle papyrus with visible, but largely illegible, writing on the black-as-charcoal surface.”

In 2008, Seales and his research team received permission from the Institut de France to examine a fragment from their Herculaneum papyri collection. This study led to a groundbreaking discovery: the presence of lead and other trace elements in the ink used on these ancient scrolls.

The findings, published in 2009 in the proceedings of the Academy’s annual program “Lire Sans Détruire les Papyrus Carbonisés d'Herculanum” (Reading Without Destroying the Carbonized Papyri of Herculaneum), marked the first reported instance of heavy metals in Herculaneum writings. Although the quantities were minute, this unexpected presence of metal-based ink opened up new possibilities for imaging techniques, the University of Kentucky writes.

The discovery of metallic components in the ink suggested that absorption-based imaging methods, such as micro-CT scans, could potentially produce contrast at the site of the writing. This insight proved crucial for future research efforts.

As a direct result of these findings, the Institut de France granted Seales and his team permission to conduct on-site micro-CT scans of two intact Herculaneum scrolls. This opportunity represented a significant step forward in the ongoing efforts to decipher these ancient texts without physically unrolling them.

The use of micro-CT technology on the Herculaneum scrolls marked a pivotal moment in the field of digital papyrology. It provided the first-ever volumetric images of a sealed Herculaneum scroll, revealing the complex internal structure and the challenges that lay ahead in deciphering these carbonized documents.

This research laid the groundwork for future developments in virtual unwrapping techniques and the application of advanced imaging technologies to ancient manuscripts. The ongoing work of Seales and other researchers continues to push the boundaries of what’s possible in reading these previously inaccessible texts, bringing us closer to unlocking the secrets of the ancient world preserved in the Herculaneum papyri.

The Vesuvius Challenge

According to the inspiration for this story, the Everything Everywhere Daily podcast, “One of the smartest things the museum officials who held the scrolls did over the years was…..nothing.”

In the late 1990s, researchers made significant progress in deciphering the Herculaneum scrolls by using advanced imaging techniques. This work focused on fragments and partially unrolled scrolls that were previously deemed unreadable.

Infrared photography emerged as a powerful tool for enhancing the legibility of these ancient texts. This technique significantly improved the contrast between the ink and the papyrus background, revealing writing that was invisible to the naked eye.

Initial experiments found success using infrared light in the 950-nanometer band to increase the contrast between the charred papyrus and ink. Further research revealed even better results in the 1000 to 2500 nanometer wavelength range and this method led to several important discoveries including philosophical works by the Epicurean philosopher Philodemus of Gadara and a poem about the Battle of Actium.

While infrared imaging represented a significant advancement, it had a notable limitation: it only worked on exposed surfaces of the scrolls. The majority of the Herculaneum scrolls remained tightly rolled, presenting an ongoing challenge for researchers.

The solution to this challenge was the establishment of the Vesuvius Challenge – launched by Seales, Nat Friedman, and Daniel Gross – in March 2023 to bring the world together to read the Herculaneum Scrolls. Along with smaller progress prizes, a Grand Prize was issued for the first team to recover 4 passages of 140 characters from a Herculaneum scroll.

“By October, a computer science student at the University of Nebraska won $40,000 for deciphering the first word from a rolled scroll. The word he found was ‘purple,’ written in Greek,” Everything Everywhere Daily reports. “It only took another four months for the grand prize of $700,000. A team of three from Germany, Switzerland, and the same student, Luke Farritor, from the University of Nebraska, claimed the prize by deciphering 5% of a scroll, and, following a year of remarkable progress, the prize was claimed.

Virtual Unwrapping Helps “Unroll” The Scrolls

“Almost two millennia after the eruption of Mt. Vesuvius hardened them into lumps of coal in 79 BCE, previously indecipherable papyrus scrolls from the ancient library of Herculaneum are finally yielding their secrets, thanks to artificial intelligence (AI) technologies created with support from the National Endowment for the Humanities (NEH),” writes NEH.

The team of researchers developed their technique by building on the foundation Seales and his team had introduced in 2015 – virtual unwrapping software. This is a revolutionary approach to analyzing ancient texts by using advanced computational methods to process CT scans of layered objects, transforming them into unrolled, three-dimensional images of their interiors.

“In March 2023, Seales’ team released this software and thousands of 3D X-ray images of the Herculaneum scrolls to the public,” NEH writes. “Since then, researchers across the globe have been training AI algorithms in the scramble to decode the scrolls’ contents.”

The grand prize-winning team was led by Youssef Nader, an Egyptian biorobotics graduate student in Berlin, and included Farritor, a SpaceX intern and college student at the University of Nebraska-Lincoln, and Julian Schilliger, a robotics student from Zurich.

“The three decoded more than 2,000 characters of text, which papyrologists have translated to a discussion of the nature of pleasure, most likely part of a previously unknown work by Epicurean poet and philosopher Philodemus of Gadara,” writes NEH. “In the translated passages, the author considers whether the availability or scarcity of goods such as food affects our experience of pleasure – and critiques intellectual rivals who ‘have nothing to say about pleasure, either in general or in particular, when it is a question of definition.’”

Several advanced technologies were used to “virtually unwrap” and decipher the Herculaneum papyri:

• X-ray Phase Contrast Tomography (XPCT): This non-invasive imaging technique was crucial in detecting the carbon-based ink used in the scrolls. XPCT can provide image contrast for light materials like carbon, allowing researchers to distinguish small variations in density between the ink and the carbonized papyrus sheet.
• Computed Tomography (CT) Scanning: CT scans were used to create detailed 3D images of the rolled-up, warped papyri without physically unrolling them. These scans provided the basis for further digital analysis.
• Virtual Unwrapping Software: Developed by Seales and his team at the University of Kentucky, this computational method analyzes CT scans of layered objects and transforms them into unrolled, 3D images of their interiors. The software follows the curved layers in the scan and virtually flattens the scrolls.
• Artificial Intelligence And Machine Learning: Advanced AI algorithms were trained to detect and identify ink on the 3D X-ray scans of the scrolls. This technology was crucial in overcoming the challenge of distinguishing the black, carbon-based ink from the carbonized papyrus.
• Volume Cartographer: This computer program, developed by Seales’ team in 2016, locates and maps 2D surfaces within a 3D object. When used with micro-CT scans, it generates high-resolution images that allow the reading of documents without physically opening them.
• Neural Networks: Researchers developed neural networks that “learn” to recognize patterns in the data indicating the presence of ink, even when it's invisible to the human eye in micro-CT images.

These technologies, combined with the collaborative efforts of researchers worldwide through initiatives like the Vesuvius Challenge, have made significant progress in deciphering these ancient texts that were previously considered unreadable.

Unwrapping All Of The Scrolls

After 275 years, the ancient puzzle of the Herculaneum Papyri has been solved. But the quest to uncover the secrets of the scrolls is just beginning. The next step is to scale the techniques noted earlier to read the scrolls in their entirety, as well as to develop an efficient scanning protocol to allow for the scanning and reading of the 300 extant scrolls, mostly in Naples.

According to the Vesuvius Challenge, two key technical problems need to be solved: segmentation at scale and scanning at scale. “The current bottleneck is tracing the papyrus surface inside the scan of the scroll,” Vesuvius Challenge writes. “Currently, we use manual tracing aided by various algorithms. This is quite expensive – about $100 per square centimeter. We spent about $200,000 so far to trace enough material to read the fifteen partial columns of text that were revealed in 2023.”

The Herculaneum scrolls present a significant challenge due to their size and the costs associated with unrolling them. Full scrolls measure between 10 to 20 centimeters in width and can reach lengths of up to 15 meters. Current techniques for unrolling these scrolls are prohibitively expensive, costing between $1 to $5 million per scroll.

With approximately 300 scrolls to decipher, the total cost could easily exceed hundreds of millions. Additionally, some sections of the scrolls are so compressed that current methods cannot unroll them at all.

To address this challenge, the focus will shift to developing auto-segmentation techniques with a goal being to reduce the cost of segmenting an entire scroll to $5,000 or less, with the hope of achieving full automation. The organization plans to adopt a community-driven approach by offering open-source “progress prizes” throughout the year, which will incentivize innovation and collaboration.

It also aims to hire the most productive contributors for full-time or part-time roles to engage in the necessary deep work. For 2024, the target is to read 90% of Scrolls 1-4, and a $100,000 grand prize is being offered to the first team that achieves this milestone. This strategy aims to leverage community expertise while tackling the practical and financial challenges of deciphering the Herculaneum scrolls at scale.

The second challenge – scanning at scale – needs to be met because “each scan currently requires the use of a particle accelerator in England and conservator-supervised transportation of the scrolls two at a time from Naples in custom-made 3D-printed cases. This costs about $40k/scroll with current techniques and is also subject to the availability of beam time,” writes the Vesuvius Challenge. “The total cost to scan all 300 scrolls could be $30M with current techniques (at current prices).”

The needed scanning breakthrough, believes the organization, will be to install one or more benchtop scanners in situ and scan the scrolls without removing them from the building. “The benchtop sources will be slower but can run every day in parallel, probably enabling us to scan all the scrolls within a few years. We don’t know that this will work, but we suspect it will be possible to get the resolution that we need from a benchtop source.”