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Breaking the pasta code
Why does raw spaghetti break into so many pieces? Science finally has the answer
Aug. 21, 2005
Toronto Star

Anyone who has ever tried to snap a handful of uncooked spaghetti in half has pondered the same question that has dogged scientists around the world: Why do the noodles splinter into numerous messy pieces that fly everywhere instead of merely breaking in two as expected?

Even the noted American physicist Richard Feynman, a Nobel laureate, winner of the Albert Einstein Award and one of the fathers of the atomic bomb, noodled on the phenomenon, although he never discovered the reason behind it.

Now researchers in Paris think they have uncovered the secret of spaghetti's brittle nature.

Sébastien Neukirch and Basile Audoly of the Mechanical Modelling Lab at the Pierre and Marie Curie Institute spent months bending pasta and photographing the results with a high-speed camera.

"We got interested in the problem when we heard about people doing fragmentation experiments on brittle rods," Neukirch said in an email interview last week.

Audoly and Neukirch believe the secret lies in a burst of destructive waves.

To the human eye, a bent piece of pasta appears to break into several pieces simultaneously.

The researchers found that's not the case. According to their experiments, when the first break occurs, it sends waves of stress down the noodle, causing other breaks.

"It took us two months to understand, compute and experiment. Quite a quick work on our time scale," Neukirch said.

While work was brisk, it was more complicated than simply bending a noodle into a circle. Such a process wouldn't have produced the uniform results needed for a scientific paper.

Instead, the researchers used a kind of pasta catapult, where a dry noodle was bent into a horseshoe shape and then released at one end. This bend-and-release process mimics the initial pasta break that occurs in everyday life, when dry pasta is bent into a curve. The broken end of the household pasta is much like the released end of the experimental noodle.

"These flexural waves locally increase the curvature of the rod, and we argue that this counter-intuitive mechanism is responsible for the fragmentation of brittle rods under bending," reads the pair's study. It is slated to appear this month in the scientific journal Physical Review Letters.

Neukirch said they used a couple hundred sticks of Barilla brand spaghetti because he found it had fewer physical defects than other varieties.

He couldn't comment on the taste, though.

"We didn't cook any of the pasta we used," he said. "It all went to the bin."

Michael Thompson, a professor of structural mechanics at University College London, England, said studying spaghetti isn't as silly as it sounds.

"(There) are a host of applications for an engineer trying to understand the fragmenting of brittle objects under stress. Concrete and brickwork are brittle, so the work is important for the collapse of buildings under earthquake shock," he said.

All brittle materials behave similarly. Spaghetti simply makes a good model because it is readily available in a "high quality rod," Thompson said.

Neukirch said his work might also be of interest to the military, as it suggests that fragmentation produces smaller pieces than previously predicted. This could be valuable information, he said, to those studying the impact of a military shell against armour or a wall.

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