I've got an article at Grantland on one of the most important variables in tennis: the physics of the court surface. I spent several hundred words describing the frictional coefficient of clay and the restitution coefficient of grass, but I end up wondering if any of this matters. Does explicit knowledge improve expert performance?
The physics of tennis might be interesting, but does it matter? Can it be used to improve performance? Or is it a useless description of the game, a complicated summary of a simple sport? In Tennis Science for Tennis Players, Brody insists that it's possible "to take advantage of the laws of nature to win more points," that players with an understanding of the game's mechanics will have a decisive edge over their more ignorant opponents. "Knowing the physics," Brody writes, "may enable you to gain a point here, a point there, and quite often, the single point is the difference between winning and losing a match."
Needless to say, most players on the pro tour haven't taken Brody's advice. Roger Federer probably isn't thinking about the angular momentum of his cross-court shot when approaching the net, just as Andy Roddick isn't contemplating the "kinetic chain principle" before unleashing his serve.
But is this a mistake? Could tennis players really improve their performance by knowing more about the equations of velocity and surface friction? To test Brody's hypothesis, I met with the Caltech tennis team, arguably the smartest collegiate athletes in the country. (The average grade point average on the men's team is 3.73, which is one of the highest team GPAs in the NCAA. And these players are taking Caltech classes.5) Despite this intellectual pedigree, the Caltech tennis players have struggled to win games: Last season, the men's tennis team went 1-16.6 Although many of the players can rattle off abstruse physics equations with ease, they all insisted that their textbook knowledge was not an advantage. "To be honest, it doesn't help at all," says Devashish Joshi, a freshman on the team. "I never think about science while playing."
The reason is obvious: The game is far too fast. Douglas Hofmann,7 a materials scientist at the Jet Propulsion Laboratory and Caltech and former assistant coach of the men's tennis team, explains why the speed of tennis makes thinking about physics all but impossible: "Let's say you're returning a serve at 125 mph," he says. "Given the length of the court, that means you've got about 0.4 seconds to execute your swing. It takes about .25 seconds just to execute a bodily movement. So that leaves just over a tenth of a second to actually think about what you want to do. If you're trying to do some computations, the ball is going right past you."
But this doesn't mean intelligence is useless, or that pro players wouldn't benefit from a crash course in Physics 101. As Hofmann points out, smarts are a crucial competitive advantage in the sport. "This is the paradox of the game," he says. "Although there isn't any time to think, the smarter guys still tend to win. Federer, Sampras, McEnroe, Connors, Agassi — these players weren't always the best athletes on the court, but they won because they played more intelligently."
And this returns us to the importance of the court surface. If the game were always played on the same material, and if this material always behaved the same way, it would be possible to dominate with a few master shots; intelligence would be far less necessary. "The sport would be a pure test of athleticism," Hofmann says. "The better physical specimen would win every time." Instead, success on the pro tour requires constant flexibility, an ability to tailor the game to an ever-changing set of surface conditions. (There is no such thing as a home court in tennis, no playing field that can be taken for granted.) As a result, players must always take the coefficient of friction into account, even if they don't know what the coefficient is. "The top-ranked guys are all intuitive physicists," Hofmann says. "They know how the ball will bounce even if they can't explain why. This is what allows them to change their strategy based on the surface."
In other words, tennis players don't need to be able to describe the physics. They just need to know it.
