Galileo may have proved Aristotle wrong when he tossed two unequal stones from the top of the Leaning Tower of Pisa, but Yale physicist Robert Adair made a far weightier point for sports fans when he dropped two unequal baseballs from the window of his third-floor study. One ball had been stored in the freezer. "The other, to my wife's infinite disgust, I kept overnight in the oven on low," Adair says. When the balls hit the driveway below, the warm one bounced twice as high as the cold one. "I had no idea the effect of temperature would be so dramatic," he says. "It opened up a whole new field of study."
Adair's work a decade ago, when he served as "Physicist to the National League" and went on to write The Physics of Baseball, was the first to highlight how subtle factors such as temperature and humidity can alter a baseball's performance. Recently, it has inspired a more urgent round of tests, because players seem to suddenly be rewriting the laws of physics. In the 1998 season, not one but two Major League players— Mark McGwire and Sammy Sosa— blasted through Roger Maris's 37-year-old home-run record. More tellingly, the average number of home runs per Major League game has been rising— from 1.47 in 1980 to 1.58 in 1990 to an astounding 2.34 in 2000.
