How to read a book without opening it

Radiation technique can aid studies of ancient texts

Ancient books

SNEAK PEEK  A radiation technique allows scientists to read the pages of ancient books without opening them.

Astrid Kopp/Flickr (CC BY-NC-SA 2.0)

Book lovers: Scientists have devised a way to read without cracking a volume’s spine or risking paper cuts (and no, we’re not talking about e-books). The new method uses terahertz radiation — light with wavelengths that are between microwave and infrared waves — to view the text of a closed book. The technique is not meant for your average bookworm, but for reading rare books that are too fragile to open.

Barmak Heshmat of MIT and colleagues started small, with a nine-page book of thick paper that had one letter inked on each page. By hitting the book with terahertz radiation and looking at the reflected waves, the scientists could read the letters within.

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Differences in the way the radiation interacts with ink and paper allowed the researchers to pick out shadowy outlines of the letters, and a letter-recognition algorithm automatically decoded the characters. The scientists could tell one page from another by using precise timing information: On the later pages, the waves penetrated deeper before reflecting and, therefore, took longer to return.

Historians also may be able to use the technique to find an artist’s signature hidden beneath layers of a painting. Sneaking into your sister’s locked diary is another story. 

Physics writer Emily Conover has a Ph.D. in physics from the University of Chicago. She is a two-time winner of the D.C. Science Writers’ Association Newsbrief award.

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