You've probably noticed this, or if not, it's a fun little experiment to try: if you try to break a strand of spaghetti, in most cases you won't be able to split it into two pieces, but at least one smaller piece will almost always form. An explanation was first provided by two French physicists and then by a group of researchers from the Massachusetts Institute of Technology (MIT), who managed to clarify why this phenomenon occurs and also identify a way to obtain a break into just two pieces. No one would think that behind a simple strand of spaghetti lies such complex physical behavior, capable of helping scientists understand how other thin, flexible materials break.
Why Does Spaghetti Break Into Multiple Pieces?
If we now know what happens when we break spaghetti, it's thanks to the work of some scientists who have reconstructed in detail the behavior of the pasta at the moment of breaking, driven by the same doubt that led you to open this article. And we'll try to explain it to you in the simplest way possible. When you hold a piece of spaghetti by the ends and bend it, the break occurs at the point where the curvature is greatest: in practice, the spaghetti reaches a level of tension that it can no longer support and breaks. It is precisely after this initial fracture, however, that the most interesting part begins. During bending, in fact, the spaghetti accumulates what physicists call elastic energy, that is, the energy that is stored within a material when it is deformed. It's the same principle that allows a rubber band to return to its original shape after being stretched. The spaghetti, however, is much more rigid: instead of returning straight, it breaks.
This accumulated energy, however, does not disappear at the moment of fracture, but continues to propagate along the spaghetti in the form of an elastic wave, a sort of impulse that rapidly passes through the two newly formed fragments. As the wave propagates, it generates new stresses that can exceed the pasta's resistance limit and cause further breakages. Simply put, the first break does not conclude the process: the energy remaining in the spaghetti continues to propagate and can break it again, which is why the final result is almost always composed of three or more pieces, rather than just two halves. This explanation was proposed in 2005 by two French physicists, who had identified the elastic wave as the cause of multiple breakages. However, one question remained unanswered: was it possible to prevent that wave from causing new fractures?
The MIT Experiment
To find an answer, MIT researchers built an experimental setup capable of controlling every movement of the spaghetti with extreme precision. The device allowed them to clamp it at both ends, rotate it by a precise angle, and slowly bend it until it broke, while high-speed cameras recorded everything that happened in the milliseconds that followed. The solution turned out to be surprisingly simple: before bending the spaghetti, the researchers applied a slight twist, that is, they rotated the two ends in opposite directions, as if they were trying to gently screw the pasta together.
Well, that small rotation changes the way energy is distributed within the spaghetti: when the first fracture occurs, some of the energy is released through torsion, reducing the intensity of the elastic wave that would normally propagate along the two fragments. The result is that the wave becomes much weaker and no longer has enough energy to cause further fractures. Under these conditions, therefore, the spaghetti finally manages to break into just two pieces.
The Mystery That Also Intrigued Richard Feynman
The behavior of spaghetti had attracted the attention of scientists long before the MIT study. According to an anecdote reported many times over the years, even the famous physicist Richard Feynman had tried to understand why it was so difficult to obtain two perfect pieces by breaking a spaghetti piece by hand. For a long time, however, the tools needed to observe what happened in the few moments following the first break were lacking. Only thanks to the most recent studies has it been possible to precisely describe the role of the elastic wave and understand that torsion can modify its behavior.
;Resize,width=767;)
