Why do strands of spaghetti so rarely snap into only two pieces? Take a look at the solution to a mystery that, no fooling, baffled famed physicist Richard Feynman.
Take a spaghetti strand by both ends. Slowly and smoothly bend it farther and farther until it snaps. Count the pieces. There could be three pieces, or one or two large pieces with a lot of small shards, but spaghetti bent in this way will rarely snap in two pieces.
This doesn't make sense. The spaghetti snaps because its curvature becomes too great. Once a weak point broken, the curvature should decrease, allowing the spaghetti to straighten out and preventing further breaks. There should always be two pieces. Nobel Prize-winner Richard Feynman spent some time trying to figure out the solution, and couldn't.
In 2005, however, a solution was found. It turns out that releasing the curve in one section of the spaghetti temporarily increases the curve in the other sections. Since the spaghetti was bent to its limit in the first place, the increase in curvature leads to many more breaks.
The idea that a break can increase tension is counter-intuitive. The Naked Scientists has a very elegant explanation of why it doesn't. Many of us have stood a thin rod of metal or plastic upright on a flat surface, put a finger on one end, and bent the rod. The example that the site gives is a plastic ruler, but it also works with tent or fishing poles.
If the pressure bending the pole is suddenly released, the pole often straightens up so fast that it jumps off the ground slightly. The momentum of the pole straightening ‘kicks' a section of it backwards enough that it hops a little.
The same thing happens when a spaghetti strand breaks. The section of the curve near the break straightens up fast. That straightening causes a kick backwards. The difference between that and the pole is instead of the kick pushing against the ground, it pushes against another section of spaghetti. Since that section is already bent to capacity, the extra push causes it to break. This same motion, the kick from one section shattering the next, can be repeated at several points in the same strand, leaving the bender with spaghetti shrapnel.
Check out slow motion films of the incredible shattering spaghetti here.