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It is a puzzle that has perplexed physicists for decades: hold a strand of dry spaghetti at both ends, bend it until it snaps, and you will always end up with three or more pieces.
In 2005, researchers in France finally discovered why: after the initial break, the brittle stick flexes back in the opposite direction, snapping itself again.
Yet a lingering question mark still hovered over the culinary conundrum. Was it possible, with the right technique, to snap a strand of spaghetti into two pieces?
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After breaking apart hundreds of pieces of pasta in a specially-constructed apparatus, a team of mathematicians led by Jörn Dunkel at the Massachusetts Institute of Technology have concluded it is possible, provided you add a twist into the mix.
MIT
Using a pair of clamps, they twisted strands of spaghetti almost 360 degrees before bringing the two clamps together until the strand broke. With this method, the found they could reliably snap the spaghetti into just two pieces.
In an effort to understand why, they used a high speed camera that recorded the shattering pasta at a million frames per second. The twist prevented the two bent strands flexing back quite as forcefully as an untwisted strand, and the untwisting motion released some of the stored energy in the spaghetti, further reducing the likelihood of a second fracture.
Why do physicists keep coming back to the spaghetti challenge? “It’s just one of those intrinsically interesting things that goes on around us,” says Dunkel.
The finding has applications for understanding the conditions under which similar materials, such as steel rods in buildings, fracture under stress. For Dunkel, it has a further benefit: “We work on a lot of things here,” he says, “but 10 per cent of them should be fun.”
Journal reference: PNAS, DOI: 10.1073/pnas.1802831115
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