# Before Kicking Someone Off a Flight, This Is What a Differential Equation Looks Like

## Take note, airplane passengers.

A flight was delayed on Thursday after a passenger complained that their seatmate was doing differential equations. Anyone that’s sat through a college math class has probably also complained about differential equations at some point too, but for those unsure about whether their neighbour is writing down regular math, or some sort of evil math, here’s a quick primer.

Guido Menzio, a 40-year-old associate professor in economics at the University of Pennsylvania, was asked to leave an American Airlines flight Thursday evening after the passenger sitting next to him saw him scrawling down something suspicious on his notepad. The anonymous passenger told cabin crew she was feeling sick, so was escorted off the plane, before telling authorities that Menzio’s notes seemed fishy.

According to the *Washington Post*, Menzio told the crew that he was writing down differential equations. When he explained the situation, the pilots seemed embarrassed and let him return to his seat, after the flight had been delayed by over two hours.

In all fairness, differential equations are scary stuff. The clue is in the name. Differential equations? Differential? Difference? They’re not like other equations. They’re differential.

For those that don’t want to watch a math video right now, here’s some words. A differential equation is like a regular equation, like x+3=4, except it’s about how a rate of change relates to a varying quantity. For example, the Lokta-Volterra equations are a set of differential equations that try to explain how the population of two species, one predator and one prey, will relate to each other. The below graph maps out how the Lotka-Volterra equations suggest the population of a group of baboons and cheetahs may change over time:

Of course, we may have completely gotten the wrong end of the stick about this story. Maybe the passenger took issue with the fact that Menzio’s equations were incorrect. In George Orwell’s *1984*, the clearly incorrect “2+2=5” is meant to represent the doublethink present in party logic. 2 plus 2 does not equal 5, but if the party says it equals 5, then you must agree that it does equal 5, even while holding the contradictory position that it does not equal 5.

If Menzio really was engaging in the Orwellian idea of doublethink, writing down differential equations that were completely flawed while knowing himself what the true answer would be, maybe there was reason to be suspicious. Maybe Menzio was trying to convince himself that he really did, in fact, love Big Brother.

As Menzio said he was flying to Ontario, where he was due to speak at Queen’s University about menu costs, it seems like that’s probably not what happened. Indeed, if he got wrong the last-minute workings out he was trying to make, it could have caused uproar at his university speech.

A spokesperson for American Airlines also said that they determined Menzio to not be a “credible threat,” and if American Airlines can’t recognize doublethink when they see it, what hope is there for the rest of us?