Deflation-gate

Obviously I made the same mistake when I confirmed Tyson's calculations. Repeating the calculation with absolute pressure and applying the ideal gas law again tells us that a temperature change of 40 degrees Fahrenheit would be sufficient to change football pressure by around 15% (of gauge pressure).So if the temperature inside the stadium rooms was 70 degrees and the outside temperature was 45 degrees, that's only a difference of 25 degrees, 15 degrees short of the required 40 degree difference. We need the footballs to have started at a temperature of around 85 or 90, not 70.This is where the process of prepping the footballs comes in. If prepping the footballs raises their temperature to 85 or 90, not unreasonable given all the handling by beefy guys around 98.6^o, and then the footballs are immediately delivered to the referees, then there's the answer.--Percy

Yes, this is true, but the leather skin constrains the flexible inner bladder. The leather skin will expand and contract somewhat with changing pressure, but the change should be very modest for modest pressure changes, which is what we're talking about here.--Percy

Didn't watch the video, huh.It was Bellichick's quarterbacks, not Bellichick, that he described as not being able to detect underflated footballs at 1 psi difference, and being hit or miss at 2 psi difference. That would be Tom Brady, Jimmy Garoppolo, Garrett Gilbert from the practice squad, and possibly Julian Edelman, a converted college quarterback who's now a receiver. I agree that actual facts would be very welcome, but I disagree strongly with the characterization of Bellichick's objections as "simple denials." Simple denial is what Faith does. Bellichick actually ran experiments and made measurements. Sorry, but it seemed like typical locker room boasting. You're not the only athlete out there with experience trying to figure out if a ball has proper pressure. In my own experience bouncing it is the only reliable way. Same thing happens in music. Tons of people have perfect pitch until you start playing notes on a piano.--Percy

We cross-posted on this issue. I already addressed the concerns you mentioned in Message 38.--Percy

The footballs aren't being inflated from scratch. They're already inflated to somewhere around 13 psi when delivered to the refs. The pressure will only require slight adjustments requiring a slight pump or release. The football surfaces of each team's 12 footballs are prepared by the respective teams, then delivered to the refs who inflate the footballs to the pressure requested by each team, somewhere between 12.5 and 13.5 psi. Each team plays only with its own footballs. Kicking balls are provided by the league and are the same for each team.Until around 2006 or so the league did provide all the balls, but the NFL finally responded to quarterback, running back and receiver complaints that unprepped footballs were difficult to throw, catch and carry, so they instituted the current system.--Percy

The refs do the inflating. I addressed this possibility back in Message 17. I don't believe they removed the balls from the field and took them inside (the pressure adjustments take place inside) where they waited for them to warm up to room temperature. Half time is only 20 minutes.But if they did take them inside and let them warm up before measuring them and they measured significantly below 12.5 psi then that seems conclusive to me. That could only happen if the refs misinflated them (seems very unlikely unless there's a defective gauge) or someone let air out of the balls.The 12 footballs in question exist somewhere. If someone were to heat them to 85 degrees and check their pressures and they came out around 12.5 psi (maybe a little less in case there's leakage) it would mean it is very unlikely that there was ever any tampering, and if they came in significantly below then it's very likely there was tampering.This is something the NFL could do right now within the hour. Then they could come out and definitively state, "Yes, there was tampering," or "No, there was no tampering," and if there was tampering then all that remains is figuring out who's responsible. There is no need to keep the Patriots and Kraft and Bellicheck and Brady hanging out to dry as tidal waves of public and media accusations of cheating and lying mount. No one should have to endure this.--Percy

Yes, exactly right. My complaint is about those rushing to judgment, not those reserving judgment.I hope I never gave the impression that I was arguing that the Patriots must be innocent. Given the current lack of evidence it isn't possible to either exonerate or convict. I've merely been calling attention to natural explanations that are being ignored in the national sports press's rush to judgment, which is apparently even more ignorant of science than I would have guessed.The NFL's investigation is on-going, and Ted Wells said it could take several more weeks, but with the flames fanned by the NFL's steady flow of leaks that casts a suspicious eye and that hurls a ton of distractions at the Patriots while they're trying to prepare for the season's penultimate game, it just doesn't seem fair.It occurred to me later that what I suggested before about taking the footballs in question, putting them in a room at 85 degrees, then measuring the pressure, might not be possible. Reports vary, but if it's true that these footballs were reinflated by the refs at halftime then they no longer have their original pressure. But some reports say they switched to the backup footballs, other reports say they switched to the Colts footballs, and if either is the case then the test I suggested would be possible.--Percy

When I tested my football I waited 1/2 hour for it to reach ambient temperature each time I moved it. As I reported earlier, the pressure changed by 2 psi with a 44 degree temperature change.Bellichick in essence did the same test, but he didn't provide temperatures, and he didn't say how long he waited for the football to reach the same temperature as its environment.Someone earlier reported on students who performed a similar test and changed the temperature of the football by dunking it in ice water for a few minutes.So whatever the heat conductivity of a football cover and bladder is, it does seem to conduct heat to the interior in a half hour or less, and much less if submerged in water instead of air. The footballs weren't inflated while cold. They were inflated while warm then taken out onto a cold field.What would be helpful to know is how warm the footballs were when they were inflated. Given that this has come up several times, I'll mention again that the footballs aren't inflated from scratch - they are already inflated when turned over to the referees, who merely adjust the pressure to that requested by the team.--PercyEdited by Percy, : Grammar.

Thanks, already done, see Message 43. I couldn't parse that first sentence, but I think I get the gist. In at least a couple earlier messages I said that if it's true that the pressure in the Colts' footballs was checked at halftime and found to be within the correct range then that is yet another mystery, because the pressure in those footballs would have dropped 1 to 2 psi once brought out on the field, depending upon how warm they were when inflated by the refs. If they were within the range on the field then they could only have been just barely within range at 12.5 psi, and even that seems unlikely. The NFL should be investigating both teams, the Patriots for underinflating, the Colts for overinflating.--Percy

The rules require that the refs inflate the footballs. The football teams are limited to prepping the balls, meaning to manually induce wear on the surface to eliminate the out-of-the-box slickness and make it easier to grip and handle.If the league feels that football inflation pressure is a significant competitive factor then they need to take temperature into account. There's been no indication in what I've read so far that league rules or procedures take temperature into account.As the season moves into winter, kicks in outdoor stadiums in the north travel less and less far. I hadn't thought about it before, but now it seems obvious that the drop in pressure in the ball must be responsible. A football's original 12.5 psi indoor pressure at room temperature would be much lower in 10 degree weather. The leather and bladder must be stiffer at lower temperatures, and that must also play a factor.--Percy

Yes, this has been explained several times. Here's another video to not watch: How Officials Check Ball PressureNo. As explained several times, the balls are prepped and inflated indoors. In that video you can see that the balls are inflated in the referees locker room. The footballs will definitely not be in thermal equilibrium with the stadium temperature, assuming that by "stadium temperature" you mean the temperature on the field. In a domed stadium indoors and outdoors (meaning the playing field) will be pretty much the same temperature. In an outdoor stadium indoors and outdoors could be at very different temperatures. Gillette is an outdoor stadium. I've since found the NFL rules on footballs (NFL Rules, click on "Ball" under the Rules dropdown), so I can say this more clearly this time. Temperature can affect a football's inflation pressure to an extent great enough to change it outside the legal range. If the league feels that football inflation pressure is a significant competitive factor then their rules need to take temperature into account. The NFL rules say nothing about temperature affecting pressure, so if the NFL thinks it important enough for temperature to be taken into account then they'll need to write new rules.Having said that I should note that there are obviously procedures in place not mentioned in the rules, such as each team specifying the pressure it wants for its footballs. I couldn't find these additional procedures anywhere online, or even any mention about whether they're written down somewhere. Yes, that would be another factor. The kicking balls are provided by the league and are kept under the control of the refs. The rules do not state what pressure the kicking balls should be at, other than the 12.5-13.5 psi range for all footballs. I couldn't find anything about whether kickers could request a certain pressure, but maybe you found something?--Percy

I think it does. Your scenario wouldn't happen because the balls start out at thermal equilibrium with the indoor environment, which is climate controlled. The footballs are being moved around indoors between rooms and hallways that are all at the same temperature. You ask this question: The temperature of the air inside the footballs when the referees get them in the referees locker room is the same temperature as the temperature inside that locker room, which is the same as the temperature in the hallway, which is the same as the temperature in the equipment room (where the footballs presumably spent the night), which is the same as the temperature in whatever room is used by the team to prep the footballs. So when you go on to say: Yes it is, assuming we don't care about temperature variations of a degree or two that are common in most climate controlled buildings.We can certainly speculate about circumstances that would affect the balls' temperature while still inside. Are the footballs in the equipment room stored next to or near a heat source like a heating vent or refrigerator? Does the prepping actually increase the temperature of the footballs, as Bill Bellichick's simulation of game day procedures seemed to find? If any circumstances like these are in play then what you say next is perfectly correct: --Percy

The NFL just can't seem to help itself. While cautioning its employees, team personnel and players to refrain from commenting on deflate-gate while the investigation is ongoing, the NFL springs yet another major leak full of comments embarrassing to the Patriots and to which they cannot respond: N.F.L. Investigator Seeks to Consult Columbia Physicist Over Patriots’ Deflated FootballsThis article states who from the law firm retained by the NFL contacted Columbia. It had access to the notes of an administrative manager at Columbia. It quotes a Columbia physicist who posted on Facebook, and another Columbia physicist who says it's more likely than not that there was tampering. It quotes a cosmologist ridiculing Bellichick's science experiments. It has a copy of a followup email from the law firm.It must be one heck of a law firm that doesn't know to initiate contact with an outside resource by saying, "There's a matter I would like to discuss with you if you can guarantee confidentiality."Unbelievable.This may be the last straw regarding Goodell's job security. Anyone who saw how ticked Robert Kraft was at the Monday press conference where he showed more emotion in a few minutes than he's exhibited during his entire tenure as owner knows his anger and frustration with Goodell must now be over the top. As I commented earlier, Kraft is one of the more influential owners in the league, and if in the end it's found the Patriots did nothing wrong then Goodell could be gone within a year or two. It will be an amicable parting because that's Kraft's style.--Percy

If at an atmospheric pressure of 14.7 psi a football with a gauge pressure of 12.5 psi and at a temperature of 72^o were cooled to 45^o, the ideal gas law yields a pressure of 11.12 psi.If at a temperature of 45^o a football's gauge pressure was 10.5 psi, then it would have to be heated to 96.1^o to yield a pressure of 12.5 psi.--Percy

Reports say the footballs tested a couple psi low. That would be in the neighborhood of 10.5 psi, but how much in the neighborhood and how much variance there was among the footballs is not known, or at least not public. They did say that one of the twelve footballs tested only a little low.How much to trust these reports, I don't know. Reports directly contradict each another on some points while reinforcing each other on other points.--Ted