How the Football Got Its Shape

And why its shape determines outcomes of the game

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The developers for EA Sports’ video game Madden NFL 13 have 10 million lines of code at their disposal, but when they need to capture the movement of a football, they spend hours in offices and hallways and even on the lawns outside, dropping, bouncing and rolling footballs and then poring over the results. “If I throw a spherical ball in the air, I know exactly where it’s going,” says software engineer Ryan Morse. “If you throw a football in the air and it lands, it can go 30 different ways.”

“It’s more like 30 thousand. Or 30 billion,” adds physicist Toan Pham, the group’s technical director.

The reason a football bounces so strangely is because of its shape. A football is a prolate spheroid, and it’s shaped that way because that’s also the shape of an inflated pig’s bladder, which is what the first footballs were made of. Soccer balls were also made of pig’s bladders, but as soon as technology permitted, those balls got rounder, which made them easier to kick. But as the football evolved — and was constructed of cowhide and rubber — it got even more prolate, which made it easier to carry and easier to throw. And much harder to pick up when it bounces on the ground.

What this oddly shaped ball — and the physics behind it — lends to our national pastime is randomness. The randomness of a bouncing ball adds an element of uncertainty that coaches and players try mightily to minimize. Indeed, the unpredictable bounce is powerful enough to determine which teams will be vying for a trip to the Super Bowl and which teams will be watching the playoffs from the comfort of their couches.

Consider the fumble. Forcing a fumble is a skill that can be practiced and learned. Some teams are better at it than others. But once the ball hits the ground, all bets are off. It will elude the grasp of a future Hall of Famer and leap into the arms of a sub from the taxi squad. The subsequent change of possession — or lack thereof — from a fumble can result in a swing of 14 points or more. In a league where the average margin of victory is 12 points, it’s no exaggeration to suggest that one random bounce can determine the outcome of a game.

That’s what happened with DeSean Jackson’s game-winning punt return against the Giants in 2010. The ball took a lucky bounce after the Eagles’ return man fumbled it, and Jackson was able to scoop it up and run for an improbable touchdown, a play selected by NFL fans as the greatest of all time.

The random bounce of the ball can even change the course of history.

Newton's Football cover
Random House

In the 2012 regular season, the San Francisco 49ers recovered 23 of 37 fumbles for a 62% success rate. The Detroit Lions recovered only 9 of 24, or 37%. Their success at collecting bouncing footballs is one of the reasons the 49ers went 11-4-1 and made it all the way to the Super Bowl. As for the Lions, they ended up a disappointing 4-12.

Just as it does in the world of science, where it drives everything from evolution to cryptography, randomness is a powerful, disruptive force in football. Coaches and players work all week to devise a game plan and execute it to perfection. Then on Sunday afternoon, the pigskin hits the turf and squirts this way instead of that. The fans erupt with frenzied cheers. Viewers at home watch the instant replay in disbelief. And the scoreboard tells a story that borders on the unbelievable.

All because of a bouncing ball.

From the book Newton’s Football, by Allen St. John and Ainissa G. Ramirez, Ph.D. Copyright (c) 2013 by Allen St. John and Ainissa G. Ramirez, Ph.D. Reprinted by arrangement with Random House. All rights reserved.

13 comments
eagle11772
eagle11772

Saying that the football's shape is a "prolate spheroid" is a big over-simplification.  A true prolate spheroid is perfectly smooth.  Obviously, a football is not perfectly smooth.  It has 4 clearly identifiable seams, and and 8 laces.  It also has a textured surface.  All of these features affect the way a football travels thru the air, bounces off the ground, bounces off players, and bounces off other things it encounters.  The shape of a football roughly APPROXIMATES a prolate spheroid, but it's shape is NOT a true prolate spheroid.

JasonBell
JasonBell

When the heck did football become America's pastime? I thought that it was baseball.... Don't remember the saying "As American as football and apple pie".

CynthiaAvishegnath
CynthiaAvishegnath

Actually, getting its shape is less a mystery than how it got its name, since the ball touches the foot a lot less than the other sport also and more rightly called football.

TroyMarcotte
TroyMarcotte

"A football is a prolate spheroid, and it’s shaped that way because that’s also the shape of an inflated pig’s bladder, which is what the first footballs were made of" 

Reading comprehension, get some.


Nate92
Nate92

Wanted to know how a football got it's shape? Well we don't have that, but here's some game developers talking about physics as we transition into fumble stats. 

elhamb3166
elhamb3166

Actually, the older, more rugby-shaped ball did have a very predictable bounce.  Teams from the 20's and 30's regularly drop-kicked field goals and good drop kickers could do it while running, usually during a wide sweep so they were often kicking at an angle to the goalposts. 


The trick was being sure that you bounced the ball off the end with it laying back toward you.  You didn't just drop it but threw it down with a fair bit of force.  The ball would rebound almost vertically at a perfect angle to take your toe dead center.  A good kicker could nail 35-40 yard field goals.


jlindsey46
jlindsey46

It's really hard to talk about the shape of the football without mentioning rugby, but the writer pulled it off! Since American football is derived from English rugby (rugby 'league,' in particular), the American football started out as a rugby ball and the shape changed as the American game developed away from rugby, e.g., prevalence of the forward pass (no forward passing allowed in rugby). Actually, the title doesn't fit the article well at all.

adnan7631
adnan7631

@CynthiaAvishegnath 

The reason why American football (and soccer in most of the world and rugby in Australia) is called football is because it is the dominant game in the country that involves teams trying to move a ball somewhere on foot. The "foot" in football refers to the fact that the game is played on foot and not on horseback. 

GrantACole
GrantACole

@jlindsey46 You are correct. This is one of the worst articles I've ever read in Time. Completely devoid of any historical sense. Fluff article only.