It doesn't happen very often, but astrophysicist Neil deGrasse Tyson was wrong this week. And like any good scientist, he's not afraid to admit it, correct it and explain himself.
On Monday, the director of the Hayden Planetarium at the American Museum of Natural History took to Twitter in an attempt to deflate the New England Patriots' Deflategate excuse.
Coach Bill Belichick had said atmospheric pressures and balls being transported from the warm indoors out onto a cold field could have caused them to lose enough pressure to fall below league standards. But Tyson tweeted that to lose as much pressure as the balls did, they would need to be inflated with 125-degree air.
"My calculation used the well-known gas formula that relates pressure to temperature within a fixed volume," Tyson explained on Facebook on Tuesday. "Quite simply, the two quantities are directly and linearly related. e.g. Halve the temperature, you've halved the pressure. Triple the temperature, you've tripled the pressure."
He wrote that his mistake was using absolute pressures instead of gauge pressures. Going by gauge pressures, the balls would need to be inflated with 90-degree air.
"A delightfully moot point since neither temperature absolves the NE Patriots even as we all know that the NE Patriots, in their 45 to 7 victory over the Colts, would have won the game no matter the ball pressure," he wrote. "And, as far as I am concerned, the Patriots would have won that game even in the vacuum of space."
Tyson could have left it at that. But he didn't, adding a postscript that explains how these same calculations are at work in far more significant ways than football deflation:
"A version of this principle even applies to the universe itself. When the famous cosmic microwave background was formed, the temperature of the universe was about 3,000 degrees (K). Since then, the universe has expanded by a factor of 1000, dropping the temperature to 1/1000th of 3,000 degrees. Or about 3 degrees (K), the current temperature of the universe."
Here's his full explanation, as posted on Facebook: