When you study physics, you're bound to brush up against some of the universe's larger mysteries. What came before the Big Bang? What lies inside a black hole? Is it possible to break a stick of dry spaghetti into exactly two pieces?
Perhaps you've found yourself asking that last question in your own kitchen. Why is it that, when you try to snap a single piece of uncooked spaghetti in half, you almost always end up with three or more pieces of pasta clattering across your counter? It's a logic-defying phenomenon that has baffled chef and scholar alike for decades; even Nobel physics laureate Richard Feynman, who helped develop the atomic bomb during World War II, is said to have spent the better part of a night sitting in his kitchen, snapping spaghetti sticks and searching for an explanation. [The Mysterious Physics of 7 Everyday Things]
Feynman came up dry, so to speak — but finally, a new study published Monday (Aug. 13) in the Proceedings of the National Academy of Sciences provides some closure. With the help of some mathematical models and a spaghetti-bending robot, researchers at MIT have found that, yes, it is possible to break a piece of uncooked spaghetti into just two pieces, but there's a twist … literally. To prevent bent spaghetti from splintering into a half dozen pieces, the researchers wrote, one end of the pasta first has to be twisted nearly 360 degrees.
Or in more technical terms, the "results advance the general understanding of how twist affects fracture cascades," study co-author Jörn Dunkel, associate professor of physical applied mathematics at MIT, said in a statement. "In any case, this has been a fun interdisciplinary project started and carried out by two brilliant and persistent students — who probably don't want to see, break, or eat spaghetti for a while."
In their new study, the MIT researchers broke more than 350 sticks of Barilla-brand spaghetti and filmed the resulting fractures with an ultra-high-speed camera. To lend their carbo-rific trials complete precision, lead study author Ronald Heisser (now an engineering graduate student at Cornell University) built a special spaghetti-bending machine, complete with aluminum pincers that gripped each noodle on either end. In each experiment, a rod of spaghetti was loaded into the machine, twisted to a predetermined degree, then bent upward until it snapped.
After much pasta destruction, the researchers discovered that they were consistently able to break individual pieces of spaghetti into exactly two pieces only when the machine twisted the noodles at least 250 degrees, then slowly bent them up to the breaking point. According to the researchers, these results were consistent across two spaghetti types (Barilla No. 5 and No. 7, which have slightly differing diameters) and agreed with a series of spaghetti-bending models the team ran before the experiments began.
So, why is the twist so important? According to the new study, the twist"enables the rod to store its energy in more than one mode." Consider that, when an untwisted rod first fractures, each half catapults backward in a burst of kinetic energy. A 2005 study found that this snap-back unleashes a wave of energy so powerful that it causes other stressed sections of the noodle to snap off as well. (That study won a 2006 Ig Nobel Prize, an annual parody award given to "improbable research.") This behavior is not exclusive to noodles, mind you, but is visible in many thin, rod-like structures — including Olympic vaulting poles.
In a twisted noodle, however, much of that snap-back wave is transferred into a "twist wave" propagated through the noodle's uncoiling, the MIT researchers wrote. The force of the snap-back is therefore weakened, and less likely to result in any more fractures occurring.
"Once [the noodle] breaks, you still have a snap-back because the rod wants to be straight," Dunkel said. "But it also doesn’t want to be twisted."
So, yes: It is possible to break your noodle into two precise pieces. Feynman would be pleased. And while this finding may be no atomic bomb, it could help future researchers better understand the mechanics of fractures in general, and even aid in the design of fracture-resistant nanomaterials. Whether these findings apply to other types of pasta — say, bucatini — will require further study.
Originally published on Live Science.
