The physics of goo

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!)


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I'm Clive Thompson, a writer on science, technology, and culture. This blog collects bits of offbeat research I'm running into, and musings thereon.

Currently, I'm a contributing writer for the New York Times Magazine and a columnist for Wired magazine. I also write for Fast Company and Wired magazine's web site, among other places. Email or AOL IM me (pomeranian99) to say hi or send in something strange!

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September 26, 2008 » 01:57 PM

From an interview with ethnobotanist and anthropologist Wade Davis:

One of the cultures you celebrate in Light at the Edge of the World is the Inuit. What do you most admire about them?

Davis: The Inuit didn’t fear the cold; they took advantage of it. During the 1950s the Canadian government forced the Inuit into settlements. A family from Arctic Bay told me this fantastic story of their grandfather who refused to go. The family, fearful for his life, took away all of his tools and all of his implements, thinking that would force him into the settlement. But instead, he just slipped out of an igloo on a cold Arctic night, pulled down his caribou and sealskin trousers, and defecated into his hand. As the feces began to freeze, he shaped it into the form of an implement. And when the blade started to take shape, he put a spray of saliva along the leading edge to sharpen it. That’s when what they call the “shit knife” took form. He used it to butcher a dog. Skinned the dog with it. Improvised a sled with the dog’s rib cage, and then, using the skin, he harnessed up an adjacent living dog. He put the shit knife in his belt and disappeared into the night.

September 25, 2008 » 11:21 AM
“Video from a camp north of Toronto in December 2005 shows a car spinning around in a nearby, snow-covered parking lot. Prosecutors characterized that as special driver training but the defense, and many outsiders, said it was nothing more than “cutting doughnuts,” a favorite winter pastime of young Canadian motorists.” - A key piece of evidence submitted in the trial of a gang of alleged young Canadian terrorists.

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