Why a Perfect Spiral Football Pass Doesn’t Break the Laws of Physics


They, too, were intrigued.

“I played football in New York City a long time ago,” said Dr. Price; he attended Stuyvesant High School, which, like Caltech, is known for its high-achieving academics and not its athletics. “I aspired to be mediocre. Never quite got there.”

Dr. Moss was a classmate and teammate of Dr. Gay’s at Caltech. “I couldn’t play anywhere else,” Dr. Moss said. “The coach gave me a red helmet and told everyone in the team, ‘Don’t kill the kid with the red helmet.’ True story.”

Dr. Price said he had not thought about this problem until he and Dr. Gay met at a scientific conference and talked about it.

“I went on to apply some pretty simple mathematics and do what physicists do,” Dr. Price said. “Which is to try and throw away all of the irrelevant details and get the heart of something. Throw away the bath water, looking very carefully to make sure there are no babies in it.”

The first thought experiment was to eliminate the atmosphere from the equations. But then the only force acting on the football would be gravity, and that would act equally on all parts of the ball and not exert a twisting torque to push the nose down. “It is always going to point in the same direction, because it’s acting as a gyroscope,” Dr. Price said. “The tip of the nose will not fall over and go down.”

Clearly, air resistance, along with gravity, was playing a key role — but not the one that the simplistic analysis would suggest. “It’s kind of cool, because you have these two effects, both of which would seem to have nothing to do with what we actually see,” Dr. Price said.

The three scientists were not the first to examine this phenomenon, and others showed through wind tunnel experiments and computer simulations that thrown footballs do not violate the laws of physics.


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