Back when he was writing the Principia Mathematica, Isaac Newton argued with his pal Chistiaan Hyugens about an interesting question: Would someone swim faster through water or through a thick, viscous goo? Newton bet you’d go slower; Hyugens argued the opposite. Newton decided to put both viewpoints in the Principia, since he couldn’t resolve it. There seemed to be no way to test it: Who was going to go to the trouble of constructing a massive tank and filling it with goo?

A professor at the University of Minnesota, as it turns out. Edward Cussler took 300 kilograms of guar gum, a thickening agent found in salad dressing, and dumped it into a 25-meter swimming pool on campus. The result was a goo twice as thick as water. He then — and I cannot imagine what these conversations would have been like — convinced 16 volunteers to jump in a swim a few laps.

“The fluid,” as Cussler told Nature.com, “looked like snot. I don’t know how to describe it any more poetically.”

The result? Turns out Hyugens was right: The swimmers didn’t go any faster in water than in the goo. Cussler says that’s because that while the goo generates more drag on your body, it also lets you generate more force with each push and kick. However, as you’d expect …

… the most troublesome part of the experiment was getting permission to do it in the first place. Cussler and Gettelfinger had to obtain 22 separate kinds of approval, including persuading the local authorities that it was okay to put their syrup down the drain afterwards.

But it was worth the hassle, Cussler says, not least because his quest for an answer made him something of a celebrity on campus. “The whole university was arguing about it,” he recalls. “It was absolutely hilarious.”

(Thanks to Stephen for this one!)