How a Digital Football Could Have Saved Us From Deflategate

Jan 29, 2015
Scientist and co-author of Newton's Football.

Pick up a football and run your fingers over the pebbled texture. Hold the ball back and notice the shape of the ball and see how it invites your hand to wrap its fingers around it. We call it a “pigskin,” but the football’s cover says cowhide. So where did this unusual name spring from?

When I co-wrote Newton’s Football: The Science Behind America’s Game with Allen St. John, we discovered that the name comes from the ball’s origin. When football began, the ball was fashioned from a pig’s bladder and was rounder than what we know today.

A mathematician would call the shape of the modern-day football a prolate spheroid, which is just a fancy way to say that it is longer in one direction than it is in the other. A lemon is a prolate spheroid, a grape is a prolate spheroid, and so is a watermelon.

MORE: The Simple Way to Make Football Safer

The design of the football evolved as the game did. The rounder shape in the days of actual pigskins worked well for a game based on carrying the ball. But as the forward pass was introduced, the ball grew more aerodynamic and became more pointed and prolate.

Rocket scientists weep when the modern football travels through the air, because it displays the same physics needed for missiles to stay in the air and for rifles to shoot a bullet. But the ball was designed to be thrown, and all fans love to see a great pass between a quarterback and a receiver. When the ball drops, however, these warrior-like football players reduce to kindergarteners as they scramble for the fumble, since the bounce of the football is unpredictable. In a word, scientists would call it random. This unpredictability and randomness of the bounce brings drama to the game, making fumble recoveries a time when everyone’s heart pressure goes up. Unlike a baseball or a basketball, it is nearly impossible to predict where a football will go when it plummets to the ground. Try the experiment yourself. Let go of a football a few times from the same height and in the same way. The prolate spheroid will not land identically, and it is this randomness that keeps the coders at EA Sports up at night. In order for a video game ball bounce to seem real in the simulated world of Madden NFL, the ball alone requires about 10,000 lines of code to produce a flight pattern and a bounce we can believe.

But this week, we have stumbled onto the science behind the football that we often overlook—the ball pressure. Deflate-Gate highlights the connection between temperature and pressure. Scientists would lovingly call this link the Ideal Gas Law. If you suffered through a chemistry class, you might have heard of it. But if you didn’t, or your memory fails you, don’t worry, because you already know the Ideal Gas Law intuitively. The law states that the pressure and temperature are in a dance: as one goes up, the other goes up. As one goes down, the other goes down, too.

Think of it this way, if you put a balloon in a sub-zero freezer, you will find that it looks wrinkled and is undersized when you return. The cold deflates the balloon. As soon as you take the balloon out of those Arctic-like conditions, it will return to its old shape. Those of us who drive in cold weather experience this, too. When you start your car in the morning, the tire pressure will be low. But as the car gets moving, the tires heat up and the pressure indicator light turns off.

It is this link between football pressure and temperature that put Mother Nature on trial over the past few days. Did the change in temperature from the locker room to the football field account for the football’s pressure change? Did Mother Nature do it? The answer is no, not fully. A systematic study is called for in order to know what really happened.

But a more pressing question is how can we prevent a Deflate-gate from happening in the future? The way that footballs are pumped, equilibrated to the right temperature, and tested for pressure requires uniformity and perhaps transparency. Measuring the ball pressure right after it is pumped up will give you a wrong reading. So a standard recipe will ensure we are not distracted by deflated balls in the future.

But, there is a bigger opportunity for footballs to enter the world of science and technology. In the future, the ball might include NASA-based pressure sensors that are embedded in the ball and used to monitor the pressure at all times. Such sensors currently exist in car tires. If they were added to footballs, officials and fans could keep an eye on the pressure through an app.

Football has come a long way from its porcine roots, and now may be ready to enter the electronic age. But what has become clear over football’s history is the best way to understand America’s game is to follow the ball.

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