MIT's New Toy Can Read Closed Books Using Terahertz Radiation

The technology could help librarians read rare books without handling them, or help snoop on sealed documents.

A group of researchers from MIT and Georgia Tech have built a device that can see through paper and distinguish ink from blank paper to determine what is written on the sheets. The prototype successfully identified letters printed on the top nine sheets of a stack of paper, and eventually the researchers hope to develop a system that can read closed books that have actual covers.