A new machine inspired by a common office toy could one day allow doctors to zap cancerous tumors using "sound bullets," scientists say.

Dubbed an acoustic lens, the device could also be used to create near photo-quality images of internal organs that surpass the resolution of modern ultrasounds.

(Related: "Exploding Bubbles Can Trim Enlarged Prostate.")

The design is based on the Newton's cradle, which features several identically sized metal balls suspended so that the balls barely touch each other.

Due to Newton's laws of motion, when an end ball is pulled back and released, the ball at the other end swings outward with the same speed, even though none