Again, let’s give the story the benefit of the doubt and assume that the Patriots’ game balls started the game at 12.5 psi. Is there any way that the pressure could have dropped during the game without tampering?

The NFL does not appear to have established any benchmarks showing how a football’s pressure changes during a game, and the referees do not appear to have measured whether the pressure of the Colts’ game-balls changed as well the Patriots’ did, so we have no control data.

That said, we have known how to calculate the pressure of a gas for 180 years, ever since French physicist Émile Clapeyron formulated something called the “ideal gas law” in 1834 — and we can use Clapeyron’s law to answer the question.

Émile Clapeyron and his Ideal Gas Law.

The ideal gas law says that three variables affect the pressure (P) of a gas; its volume (V), its amount (n), and its temperature (T). This may come as surprise anyone who has read anything about DeflateGate.

The accepted premise of DeflateGate remains, as the scandal’s name implies, that the only way to change the pressure of a football is to let some air out — i.e. to change the amount of gas inside the ball.

But, as Clapeyron’s law tells us, there are two other ways to change the pressure of a gas: by changing its temperature, or by changing its volume.

During the Colts-Patriots game, the temperature started in the low fifties Fahrenheit and fell to the high forties as the evening wore on. The temperature in the room where the referees measured the ball is not known, but it was probably around seventy degrees.

How much of a pressure drop can a temperature change of twenty degrees Fahrenheit cause?

The math is a little more complicated than Clapeyron’s law, because we have to translate psi and degrees Fahrenheit to different units, Pascals and Kelvin — and also account for atmospheric pressure and convert to gauge pressure. All things being equal, a drop in temperature of one degree Fahrenheit should cause a drop of about one third of one percent in pressure.

The approximately twenty degrees Fahrenheit drop in temperature between the time the balls were approved, and the time they were found to be below regulation pressure, could therefore account for a pressure change of around 7%, taking the initial 12.5 psi down to 11.6 psi.

The other variable is volume. Gas is a fluid, meaning (more or less) that it takes on the shape and size of its container, in this case a football. Does a football change shape or size during a game? Yes. A football is made of cowhide leather, which softens and stretches when wet. The change in volume caused by this stretching can account for as much as another 6% reduction in pressure, which would cause an additional pressure drop of around 0.75 psi.

Combine these two factors — falling temperature plus falling rain — and a pressure drop from 12.5 psi to 10.9 becomes much less scandalous.

Oh, there’s another variable, too, not accounted for in the ideal gas law (so-called because it calculates the behavior of gas under “ideal” conditions): the accuracy of the referee’s pressure gauge. Commercial and general service pressure gauges are not scientific instruments: they provide approximate values, accurate to somewhere between plus or minus 1% to plus or minus 2.5%. We do not know what type of gauge referee Anderson used, but its degree of accuracy may account for an additional variation in his pressure measurements.

In short, it is almost certain that there was no deflation in #DeflateGate, deliberate or otherwise.

You can see a paper about that here. The entire DeflateGate story is based on a misunderstanding of what air pressure is, and how it changes. Given that, how did it become a subject that obsessed much of America for more than a week?

That, in fact, is what is important about the story.

DeflateGate started when Bob Kravitz, a reporter for WTHR, an NBC-affiliated TV station in Indianapolis, got word that the referees had changed the Patriots’ footballs during the game against the Colts. Kravitz had an incentive to break the story and position it as possible cheating: his most important audience was a group of disappointed Colts fans whose team had just lost a game.

The claim that the Patriots had deflated footballs to gain an advantage was a good way for Kravitz to play to his crowd. It was also easy to make: neither Kravitz, nor most of his audience, have the scientific literacy needed to understand that a relatively small drop in psi is not evidence of deflation, tampering, or cheating, and Kravitz had zero incentive to check any of that before breaking the story.

And that’s the real DeflateGate scandal: Americans’ scientific illiteracy.

We can’t expect much scientific literacy from a sports reporter and his audience of heartbroken sports fans, but what about in our general public discourse?

That’s where we have a big problem.

Journalists from all over America picked up Kravitz’s story. And almost every one of them revealed that they did not know enough science to see, or even discover, the truth. The footballs, almost every news report you can find will tell you, must have been “deflated.” It was not only the pressure that had changed. It was the amount of air. There was no other possible explanation.

The fact that there was no baseline measurement, no control data, and we had a nearly two hundred-year-old scientific law to tell us things might be otherwise, did not enter into much of the reporting.

Few journalists have the scientific literacy to ask the right questions, and, partly as a result, few of their readers, viewers, and listeners have the scientific literacy to notice or care.

And when the media did try to use science, it was horrible. Slate’s analysis of the Patriots’ “impossible” ball handling skills was cooked and invalid; Slate also claimed that taking the air out a football would make it significantly lighter, a confusion caused, perhaps, by the fact that the NFL said it weighed its footballs, and weight can be measure in pounds, and pressure is measured in pounds per square inch.

And what of Bill Nye, America’s “Science Guy”?

For all his good work, Nye is not a scientist, but a man with an undergraduate degree in mechanical engineering. There is nothing wrong with being a mechanical engineer, but it does not make you a scientist.

Nye’s attempt to address DeflateGate by putting footballs in a refrigerator proved as much: it was a well intentioned attempt to use the interest in DeflateGate to get people to pay attention to an actual problem, climate change, but, despite his moniker, Nye got the science wrong, hurting, instead of helping his cause.

(Do not be surprised when one day a climate denier tells you that “Bill Nye said science proved the Patriots deflated those footballs, and he was wrong about that, so why should we believe scientists when they talk about climate change?”)

Zogby Analytics asked Americans to name a living scientist. Neither Bill Nye (5%) nor Mehmet Oz (1%), also known as “Dr. Oz”, are scientists. Chart from http://bit.ly/1K1iXs4

When it comes to the trivia of professional sports, our scientific illiteracy really does not matter. But in the real world, where we must make decisions about everything from technology, vaccinations, and economic policy to education, transcontinental gas pipelines, and climate change, it really does.

Twenty-first century America needs a scientifically literate electorate informed by a scientifically literate media. DeflateGate proves we do not yet have either.

(P.S. The “employee of interest” who “went to another area” with the footballs? That was, apparently, just an elderly locker room attendant going to the bathroom.)