After two millennia, scientists wielding X-rays have finally revealed the text of an ancient library long thought to be unreadable.
Blasted by the volcanic eruption of Mount Vesuvius that also demolished Pompeii in 79 CE, the library in Herculaneum, which contained around 1,800 rolled papyrus scrolls, has tantalized classical scholars since archaeologists first unearthed it in 1752. While many of the scrolls did not burn, they were carbonized, locking pages of ancient text into fragile tubes resembling the charcoal remnants of a campfire.
Previous attempts to read the scrolls that may once have belonged to Julius Ceasar’s father-in-law have been highly damaging, chastening future would-be readers. But yesterday, an international team of scientists, led by Vito Mocella of the Institute for Microelectronics and Microsystems in Naples, Italy, and Emmanuel Brun of the European Synchotron, announced that that X-ray phase contrast tomography enabled them to read the text layered inside the scrolls without ever having to unroll them. The technique can detect differences in how similar materials—such as ancient ink and papyrus—bend light. They published their results in the journal Nature.
Richard Van Noorden, reporting for Nature News, explained the technique:
This is used in medicine to image the structures of soft tissues that do not absorb x-rays well, such as those in the brain, lungs and breast. It works by detecting contrast in how materials refract, rather than absorb, X-rays. Inside the Herculaneum scrolls, the inked letters are raised some 0.1 millimetres above the surface of the papyrus. That tiny bump was enough for Mocella’s team to make out the ink using coherent beams of X-rays from the European Synchrotron Radiation Facility in Grenoble, France.
From those bumps, the team could read a number of Greek letters and even a few words. Mocella and Brun admit that there are several limitations to using X-ray phase contrast tomography to read ancient text, including how to decide which direction to read words that may be folded or upside down.
But it does show promise, they said. “While our first experiments have revealed only small segments of writing and are in need of further refinement,” the authors wrote, once the technique has been perfected, “the imaging of an entire papyrus scroll should not require more than a few hours.”