The physicist’s puzzle: Why can’t spaghetti be folded in two?

2022-04-28 0 By

Pick up a piece of raw pasta, hold both ends in your hands and slowly bend. When you hear the sound of “snap”, the pasta does not break in two, but in three. Once, it may be accidental, but no matter how many times you try, the pasta will never break in two.Why doesn’t spaghetti break in two?The phenomenon has been known for centuries, with physicist James Feynman battling hundreds of sticks of pasta in his kitchen but still unable to figure out why it happens.It wasn’t until 2005 that two Physicists from France, Basile Audoli and Sebastien Neujich, discovered the secret after repeated research.When pressure is applied evenly at both ends of the spaghetti, it bends to a critical point, and then at the instant it breaks, the spaghetti quickly bounces back and straightens from its bent state.Because of inertia they will bend in opposite directions, creating a wavy vibration that will cause the two pieces of pasta to break again, meaning that the initial break triggers a “rebound effect” and a “bending wave” that will cause the whole strip to vibrate and break into multiple parts.Is there a way to break pasta in two?In 2018, two PhD students from Cornell University and MIT came up with the answer, using “warping” and “quenching”.They designed a mechanism that rotates the pasta on one end and slides the other back and forth to control how much it bends.A camera was also used to record the pasta breaking at up to a million frames per second.After hundreds of experiments, the researchers found that if they twisted the pasta 270 degrees, then slowly bent it into two pieces.How does this work?It turns out that after twisting the pasta, the noodles will want to return to a flat state first, creating a torsion wave called a “bend wave.”It travels faster than the rebound wave, releasing some of its energy and thus preventing subsequent fracture, a phenomenon known as the “reverse torsion effect.”Releasing a certain amount of energy helps to reduce the resistance of the pasta in the process of breaking, while the quenching speed is 5mm/s.The experiment, though seemingly useless, ended Feynman’s experiment after decades of research, a knowledge of the physics of pasta was successfully perfected and even won an Ig Nobel Prize, contributing to our knowledge base.