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Charles M. Lieber, a major figure in nanotechnology, asked one of his graduate students in 1998 to undertake the design of a radically new type of computer memory. It would read and write digital bits with memory elements that measured less than 10 billionths of a meter (10 nanometers). Until then, the student, a German native named Thomas Rueckes, had been spending his time in Lieber's laboratory at Harvard University measuring the electrical and material properties of carbon nanotubes. These cylinders, measuring but a nanometer or so in diameter, display a surface of hexagonal carbon rings that give the material the appearance of a honeycomb or chicken wire. Since the discovery of nanotubes in 1991, the scientific community has lauded them for their superlative material and electrical properties.
Lieber wanted to know whether Rueckes could come up with a concept involving nanotubes that could be submitted for funding under a molecular electronics program funded by the Defense Advanced Research Projects Agency. Rueckes pored over books and review articles for a few days, but nothing good suggested itself. One evening he left the chemistry lab and crossed the street to the cafeteria at the Harvard Science Center. On his pizza run, he passed the Harvard Mark 1, the 55-foot-long monstrosity, a predecessor of modern computers, that had served the U.S. Navy as a calculator for gunnery and ballistic computations until 1959. It now decorated the center's hallway. Back in the lab, he remembered that the Mark 1 operated by moving mechanical relays from one position to another. "That is what flipped a switch in my brain," he remembers. "I could see a picture of how to build a memory."