A charred lump the size of a fist is all that remains of a scroll from the library of the Roman city of Herculaneum. Buried by the eruption of Mount Vesuvius two thousand years ago, the text hidden inside has gone unread ever since. Physically unrolling such a scroll would turn it to ash. But now archaeologists no longer have to take that risk.
Specialists placed the scroll in an X-ray microtomograph at beamline BM18 of the European Synchrotron in Grenoble. The instrument scans the object from multiple angles and builds a three-dimensional density map — much like a hospital CT scanner, but with resolution down to thousandths of a millimeter. Then algorithms took over: they carefully "unrolled" the virtual scroll into a flat strip, as if smoothing out a rolled sheet in digital space.
The result is the first complete digital reading of scroll PHerc. 1667 from start to finish. The text is ready for scholarly study, and not a single fragment of papyrus was damaged. In another scroll (PHerc. 139), the title page was recovered: the author is Philodemus, and the title is On Gods, book 8. This is no longer guesswork but a systematic approach: the technology is ready to tackle the entire library.
That charred lump is silent no more. The synchrotron beam and a chain of algorithms turned fragile carbon into an open book, and there are hundreds more such books in Herculaneum.
The ink in the Herculaneum scrolls is carbon-based, so its density is almost identical to that of the carbonized papyrus. To "see" it, researchers had to look not for density differences but for microscopic surface irregularities, like reading an invisible inscription by feeling the paper.