How to Turn Your Fist Into a Block-Breaking Machine

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.”