Few things in life offer more visceral proof of the power of physics than a karate chop. Punch a brick with your bare hand, and if you are untutored in the martial arts, you may break a finger. Punch it with the proper force, momentum, and positioning, and you’ll break the brick instead. “Amazingly, there are no tricks involved,” says Michael Feld, a physicist at MIT. “What you have here is one of the most efficient human movements ever conceived.”
In the late 1970s, when Feld was earning a brown belt in karate, his instructor, Ronald McNair, also happened to be his physics student. (McNair died in 1986 while working as a scientist-astronaut aboard the space shuttle Challenger.) The secret to karate, both men agreed, lies in the speed and focus of the strike. But just how fast does a karate punch move? To find out, they joined with undergraduate ...
