By Nathan Seppa
Picture sitting at a baseball park, leisurely watching a game. Your mind wanders, torn between a box of Cracker Jack and the conversation drifting down from the row behind you. Suddenly the crack of a bat snaps you to attention, and you scan the field for the ball. Physicist Alan Nathan would say your attention is piqued because well-hit balls make a different noise than weak pop-ups do.
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“You hear a high-frequency sound,” says Nathan (below). There’s a duller thud when the ball misses the bat’s “sweet spot,” he says, the point where a hit maximizes the outgoing speed of the ball.
Physics and baseball are a natural marriage, as Nathan realized 16 years ago when he took a break from experimental particle physics to talk to high school kids about science and casually chose baseball as the topic. He got hooked and spent a whole sabbatical analyzing the bat-ball collision, the dynamic core of the sport.