At the Massachusetts Institute of Technology, students earn them by writing a dissertation. Lots of them. Ben Paris, a fourth-degree black belt in tae kwon do, is happy to demonstrate his grasp of the scientific principles. First, he adjusts his belt. Then he lets out a short, sharp yell, snaps his left leg forward, and smashes his foot through three boards, showering the mat with splinters.
Few things offer more visceral proof of the power of physics than a karate chop.
Punch a brick with your bare hand, untutored in the martial arts, and you may break a finger. Punch it with the proper force, momentum, and positioning, and you'll break the brick instead. What you have here is one of the most efficient human movements ever conceived. We've found nothing in our studies to improve upon the art. In the late 1970s, when Feld was earning a brown belt in karate, his instructor, Ronald McNair, also happened to be his physics student.