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On Tennis' 'Hawk-Eye,' Science is a Buzz-Kill

In 2006, tennis fans were awed by a new technology that would help officials judge disputed line calls. The system, called "Hawk-Eye," added an incredible new facet to the sport. Players could now challenge questionable line calls. No more would players be held hostage by the imperfections of human judgement and eyesight. Technology was here to save the day.

Five years later, Hawk-Eye is the most successful example of technology being used to help officiate a sport. Not only is it accurate to within 3.6 millimeters, Hawk-Eye adds a new level of excitement to tennis. Challenges are displayed for all to see on television as well as on the stadium big screen. The crowd claps in unison and anxiously looks on as the ball flies through its trajectory from racket hit to court contact. Will it land in or out? What drama! The result is greeted by a raucous mixture of sighs, groans, cheers, or even colorful metaphors depending upon the outcome.

hawk-eye-tennis1.jpgIt doesn't get much closer than that.

Hawk-Eye is an incredible piece of technology. Using anywhere from four to ten high-speed video cameras positioned around the tennis court, the system triangulates the exact 3-D position of the ball throughout the rally. It also takes weather and other environmental conditions into account. According to Hawk-Eye Innovations:

[Triangulation] is repeated for each frame so that the 3D positions of the

ball can be combined to produce a single trajectory of the flight of the

ball. The trajectory is then used to calculate an exact bounce contact area the ball made with the court.


So, technically, the digital mark that you see on the Hawk-Eye replay is only the projected strike of the ball on the tennis court. This has prompted two British scientists, Henry Collins and Robert Evans, both of Cardiff University, to question the system's legitimacy.

"It's absolutely vital to have a health warning stamped on this because

what you see with Hawk-Eye doesn't always correspond to what's actually

happened," said Harry Collins, a social sciences professor at Cardiff

University.  "When [Hawk Eye] says that a ball was 1 millimeter in, what they should say is that 'it was 1 millimeter in, we think.'"

Collins and Evans released an in-depth review of Hawk-Eye in a recent issue of Public Understanding of Science, in which they pointed out the technology's flaws. The authors insisted that the use of Hawk-Eye represents a "false transparency" because it is used without offering "appropriate knowledge of its limitations." Thus, Hawk-Eye gives the impression that justice is being done when, in fact, it may not be.

Collins and Evans suggested that the role of Hawk-Eye in tennis should not be used to grant epistemological privilege. Instead, it should be used merely to avoid big mistakes. To fix this, they recommended creating a "zone of uncertainty." If the tennis ball is shown to land within this zone, then the original call should be enforced.

Despite these scientists' misgivings, Hawk-Eye has been hailed as a tremendous boon for tennis and calls have been made to extend its use to both baseball and soccer.

While Hawk-Eye does have inherent scientific imperfections, in this case, science simply serves as a buzz-kill. As we have seen in tennis, Hawk-Eye has been almost universally accepted as both a fair and exciting addition to the sport. Seeing as how the basic goal of any sport is entertainment, the consensus appeal of Hawk-Eye should determine its success, not science.

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Ross Pomeroy
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