In a feat worthy of Superman, scientists have read a letter sealed in 1697—without opening it. Instead, they used a high-resolution x-ray scanner to see through layers of paper and a computational algorithm to digitally unfold it, NPR reports. The letter, a request for a copy of a death certificate, was intricately folded using “letterlocking,” a common way to prevent tampering before the invention of the envelope. The new approach to reading old closed letters not only avoids damaging paper, the researchers write today in Nature Communications, but it also preserves the unique folding patterns that were once a top-level security strategy.
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