Sound Bullets Inspired By Newton's Cradle Could Sink Subs, Pummel Underground Bunkers, Destroy Tumors
Inspiration comes from the strangest places. A falling apple supposedly inspired Newton's laws, and now a desktop ornament bearing Newton's name has inspired a new acoustic weapon that both militaries and hospitals can keep in their arsenals: sub-sinking, tumor killing "sound bullets." Researchers at Cal Tech, using a modified renditions of Newton's cradle - those stainless steel balls suspended by wire that make a seemingly endless clatter once set in motion - have figure out a means of concentrating and amplifying sound waves in a way that makes them an extremely destructive acoustic force. The team essentially used a metamaterial to create an acoustic lens. They lined up 21 parallel rows of ball bearings on the acoustic lens, each containing 21 bearings with weights attached to the end to vary the pressure in each row. The team then dropped another small ball onto one end of a row, causing a compression wave...