Particle accelerator experiment that could rewrite the history of the printing press

I’m a little nervous. In my right hand I hold a priceless piece of human history. This is not an exaggeration. It’s a weathered black binder with gold text printed on the front. In Gothic text it reads “A Leaf of the Gutenberg Bible (1450 – 1455)”.

Yes, That Gutenberg Bible. These original pages, dating back to the 15th century, have come to the SLAC National Accelerator Laboratory in Northern California, blasted by high-energy X-rays. In addition to pages from the Bible, a 15th-century Korean Confucian text, a page from a 14th-century Canterbury Tales, and other Western and Eastern texts, they will all survive the bombardment. In these priceless documents, researchers hope, clues to the evolution of one of humanity’s most important inventions, the printing press, can be found.

A beam from SLAC’s synchrotron particle accelerator scans a page of the original Gutenberg Bible (1450-1455 AD).

SLAC National Accelerator Laboratory

“What we’re trying to understand is the elemental composition of ink, paper, and maybe the remnants of fonts used in these Western and Eastern prints,” said imaging consultant Michael Toss.

For centuries, it was widely believed that Johannes Gutenberg invented the printing press in Germany around 1440 AD. He is thought to have printed 180 Bibles (less than 50 are known today). But recently, historians have found evidence that Korean Buddhists began printing around 1250 AD.


A page from the Gutenberg Bible from Peter’s letters, mid-15th century.

Jacqueline Ramseyer Orrell/SLAC National Accelerator Laboratory

“It’s not clear if the two inventions are completely independent, or if there is a flow of information,” said Uwe Bergmann, a professor of physics at the University of Wisconsin. “If there is a flow of information, of course, it’s from Korea, to the West, to Gutenberg.”

To put it more clearly: Was Gutenberg’s invention based at least in part on Eastern technology? That’s where the Stanford Synchrotron Radiation Light Source comes in.


“Spring and Autumn”, Confucius, c. 1442.

Jacqueline Ramseyer Orrell/SLAC National Accelerator Laboratory

A synchrotron is a particle accelerator that fires electrons into a giant ring-shaped tunnel to generate X-rays (instead of SLAC’s better known linear particle accelerator, the two-mile LCLS). These X-rays allow scientists to study the structure and chemical properties of matter. To see exactly how they use SSRL to research priceless documents, watch the video above.

By firing an SSRL beam of X-rays thinner than a human hair into a piece of text on a document, the researchers could create a two-dimensional chemical map detailing the elements present in each pixel. This is a technique called X-ray Fluorescence Imaging, or XRF.


Stanford Synchrotron Radiation Light Source (SSRL) at SLAC National Accelerator Laboratory.

SLAC National Accelerator Laboratory

“The atoms in this sample emit light, and we can trace which elements in the periodic table that light must come from,” said Minhal Gardezi, a doctoral student working on the project.

As powerful as SSRL’s X-rays are, they don’t damage documents, giving scientists a complete picture of the molecules that make up ancient documents. They also allowed them to look for trace metals that historians believe shouldn’t be in the ink. This suggests they may have come from the printing press itself. “This means we can learn a little bit about alloys that were used in Korea and Gutenberg, and then alloys that may have been used by others later,” Bergman said.


Scientists can use X-rays to create two-dimensional chemical maps of ancient texts, like this Confucian document.

Mike Toth/SLAC National Accelerator Laboratory

If they find similarities in the chemical composition of the documents, it may help ongoing research into the similarities and differences in printing techniques, and whether there is an exchange of information from East Asian to Western cultures.

However, every scientist I spoke to on the project made it clear that even finding similarities between the two documents would not definitively prove that one technique influenced the other.

The documents were borrowed from private collections in Korea, the Stanford Library and Archives. The SLAC research is part of a larger project called “From Jikji to Gutenberg” led by UNESCO. The findings will be released at the Library of Congress next April.

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