Answering real questions, German physicists and nuclear engineers set out to discover why beer coasters never fly straight when you throw them

Answering real questions, German physicists and nuclear engineers set out to discover why beer coasters never fly straight when you throw them

No one does drunken science quite like the Germans

CultureJuly 28, 2021 By Will Brendza

Cardboard drink coasters (AKA “beer mats”) are a staple of pubs, bars, saloons, breweries and watering-holes around the world. They’re there to prevent drunk patrons from getting bar-tops all sopping wet and leaving those unsavory table rings on wood surfaces.

But they’re also there to be used for any number of bar games. The entertainment value of beer mats is just as high as their functional value.

Anyone who’s ever played around with them, though, knows that they fly about as straight as Elton John. Which is to say: they’re hard to aim. That’s part of what makes them such perfect bar game projectiles. They’re unpredictable, erratic and irregular missiles.

But have you ever wondered why?

That’s exactly the question that German physicists at the Helmholtz Institute of Radiation and Nuclear Physics and the Argelander Institute for Astronomy at the University of Bonn wanted to answer. As so many historic scientific inquiries began, this one, predictably was born at a pub over beers. The physics show team from Bonn was drinking at a bar when they noticed that the usual throwing technique resulted in beer mats unavoidably drifting off after 0.45 seconds at most.

So the team did what any physicists would do in their position: they returned (drunkenly) to the lab and built a machine to fire beer mats at a perfectly consistent speed and angle and started taking measurements with a high-speed camera. And what they discovered is absolutely non-revolutionary in every way — but it satisfied their curiosity.

“A beer mat is usually rotated when thrown, similar to a frisbee,” explains Christoph Schürmann from the Argelander Institute for Astronomy at the University of Bonn. “This turns it into a kind of spinning top.

That is typically a good characteristic for flight — however, without those nifty aero-ridges on the bottom of a frisbee, that hold the disc aloft, beer mats tend to list off to one side as they fly through the air. Which transforms their action from being “top-like” to being more “wheel-like.” Thus, the centrifugal force exerted by the spinning disc is aimed down and backward instead of forwards and side-ways, forcing the disc downwards.

Eureka! They had an answer, and with it, they published a paper in the European Physics Journal Plus titled, “Beer mats make bad frisbees.”

“There is no application for the project,” says Prof. Dr. Carsten Urbach from the Helmholtz Institute of Radiation and Nuclear Physics, at the University of Bonn. “However, the problem is clear for laypeople and physicists alike. And it wonderfully illustrates the entire process by which the natural sciences acquire knowledge — from the observation to the theory and its experimental testing, right through to its adjustment and further development.”

In other words: it may have been pointless, but it wasn’t exactly fruitless. If for no other reason than to demonstrate how the scientific method works — even drunkenly.