The Carbonized Scrolls
Brent Seales and the Virtual Unwrapping of the Herculaneum Library
Carbon ink written on a carbonized papyrus scroll possesses the exact same atomic number—$Z = 6$—as the burnt reed fibers underneath it, rendering two thousand years of classical literature invisible to conventional X-ray radiography. For twenty-five years, that law of atomic physics blocked every attempt to read the last intact library surviving from Greco-Roman antiquity: the charred scrolls of Herculaneum.
In the autumn of 79 CE, when Mount Vesuvius erupted above the Bay of Naples, Herculaneum was struck by superheated pyroclastic surges. Avalanches of volcanic gas and ash traveled at over a hundred kilometers per hour at temperatures reaching 320 degrees Celsius. Inside the Villa of the Papyri, owned by Julius Caesar's father-in-law Lucius Calpurnius Piso Caesoninus, the blast wave flash-heated a philosophical library of roughly 1,800 Greek and Latin papyrus scrolls. Twenty meters of volcanic mud then smothered the rooms and hardened into tufa rock. Deprived of oxygen, the scrolls did not burn to ash. Instead, like wood heated in a charcoal kiln, the cellulose of the papyrus reed underwent pyrolysis, transforming every scroll into a black cylinder of carbon.
Rediscovered between 1752 and 1754 when Swiss engineer Karl Weber and workmen dug shafts sixty feet through the volcanic rock, the Herculaneum scrolls proved agonizingly fragile. Early attempts to slice the rolls open in Naples destroyed hundreds of columns. Even after Vatican scriptor Father Antonio Piaggio invented a traction frame in 1756 that glued ox-gut membrane to a scroll and peeled back layers with silk threads, hundreds of tighter scrolls remained fused. Whenever mechanical tension touched the brittle charcoal wafers, they shattered into black flakes. Curators in Naples, Paris, and London eventually locked roughly six hundred unopened scrolls away.
In 2015, University of Kentucky computer scientist W. Brent Seales proved that a burned scroll could be read without opening it when his team virtually unwrapped the carbonized sixth-century CE En-Gedi Scroll from Israel, discovering the Book of Leviticus inside a lump of charcoal. Yet the En-Gedi ink contained trace lead and iron salts that glowed brightly in a micro-CT scanner. First-century Roman and Greek scribes, however, wrote on papyrus using atramentum librarium, an ink ground from pine-pitch lampblack soot mixed with gum arabic. Because lampblack soot contains no heavy metals, firing X-rays at a Herculaneum scroll produced zero absorption contrast between the ink and the page.
Refusing to concede that the ink had left no trace, Seales carried two unopened scrolls from the Institut de France in Paris (PHerc. Paris. 3 and PHerc. Paris. 4) and detached fragments to the Diamond Light Source synchrotron in Oxfordshire in 2019. There he scanned them with phase-contrast micro-computed tomography at a voxel resolution of 8 micrometers ($0.008\text{ mm}$). When entrepreneurs Nat Friedman and Daniel Gross joined Seales in March 2023 to launch the $1,000,000 Vesuvius Challenge, the global team built a three-stage pipeline to solve the zero-contrast bottleneck:
- - 8-Micron Synchrotron Phase-Contrast Micro-CT: Instead of measuring only X-ray absorption (which depends on atomic number $Z$), synchrotron phase-contrast tomography measures the refractive phase shift of coherent X-ray wavefronts passing across microscopic density boundaries. That phase shift resolves every cellular vascular bundle of the papyrus pith inside the sealed scroll at 8-micron 3D voxel resolution.
- - 3D Topological Mesh Segmentation and Virtual Flattening: Because the volcanic mud had crushed the spiral rolls into twisted accordions with over a hundred overlapping wraps, competitors built automated segmentation algorithms (ThaumatoAnakalyptor). These traced a continuous manifold surface through the 3D point cloud and unrolled each virtual sheet into a flat plane without crossing adjacent layers.
- - Sub-Micron Ink Relief Detection via 3D Neural Networks: Unlike fluid iron-gall ink that soaks into parchment, viscous carbon-soot ink sat as a dried crust on top of the papyrus fibers, creating a sub-micron thickness bump and a crackled surface texture (craquelure) when carbonized. Training 3D neural networks on infrared photographs of broken fragments, student Luke Farritor detected the first complete Greek word inside the unopened Paris scroll in October 2023: $\Pi\text{OP}\Phi\text{YPA}\Sigma$ (porphyras, purple).
Building on that breakthrough, Youssef Nader, Luke Farritor, and Julian Schilliger combined autonomous sheet segmentation with ensemble 3D ink-detection transformers to capture the Grand Prize. In February 2024, without unrolling a millimeter of the charcoal cylinder, the team extracted fifteen columns of Greek text by the Epicurean philosopher Philodemus on music, food, and the mechanics of human pleasure.