Researchers from the University of Oxford and Lancaster University have developed a 'self-playing' guitar string.
Essentially, the string vibrates by having an electrical current pass through it and force it into motion.
According to an article published on the UK’s iNews, the two university teams mounted a carbon nanotube wire that was 100,000 times thinner than a traditional guitar string on metal supports, cooled it to 0.02 degrees above zero and passed an electrical current through it, which caused it to vibrate.
As for the specifics? Lead researcher Dr. Edward Laird of Lancaster University explained that the individual electrons from the electrical current “hop one by one onto the wire, each giving it a small push.”
He went on to note that while these "pushes" are usually random, if the parameters are tightly controlled the electrons will synchronize and create an oscillation.
Because the nanotube is much thinner than a guitar string, it oscillates at a much higher frequency – one that is in the ultrasound range and unable to be detected by human hearing.
But, Laird said, it was still possible to assign it a note. “Its frequency is 231 million hertz, which means it's an A string, pitched 21 octaves above standard tuning."
iNews goes on to report that, back in 2004, researchers from Cornell University in New York also experimented with using nanotubes one million times thinner than guitar strings in order to weigh various items.
Explained Cornell professor Paul McEwen to the BBC's Science In Action program, "If you imagine that you had a guitar string and you glued a little weight on to it, it would lower the frequency at which the guitar string vibrated, because the extra mass slows it down. The same thing happens here, but our string only has a few tens of thousands of atoms in it.
“So, just a few extra atoms, maybe even one, might shift the tone of the vibration enough for us to detect it."