# Pasta puzzle

I’ve been having a lot of fun reading “How to Fossilize Your Hamster“[1], an entertaining and enlightening collection of quirky science questions and experiments one can do to observe the the principles. It’s very conversationally written with abundant humor. For example, in answering the best way to get ketchup out of the bottle, where they detail seven methods to “exploit the thixotropic nature of ketchup,” they begin with:

“WHAT DO I NEED?

• A meal requiring tomato ketchup (it’s not essential, as you can do this experiment using an empty plate, but there’s no doubt that French fries enhance the experience)
• a glass bottle of tomato ketchup” [1, page 48]

What’s not to like about that?

My favorite question was “Pasta Puzzle:” if you hold a strand of spaghetti at both ends and bend it, why will it nearly always break into three or more pieces? Audoly and Neukirch[2] made some fun-to-watch videos of their experiments. In the first phase, they did high-speed filming of spaghetti breaking. To add control to their experiments, they then held bent spaghetti while inducing a break with a pair of scissors. They eventually reduced the problem to a catapult experiment, in which they demonstrated that spaghetti can be broken by merely releasing one of its ends[2]. In their paper, they also come up with an “analytical prediction of breaking events” in “perfect spaghetti.” It should come as no surprise they earned an igNobel award.

Their conclusion:

“[T]he sudden relaxation of the curvature at the newly freed end leads to a burst of flexural waves [that] locally increase the curvature in the rod and […] is responsible for the fragmentation of brittle rods under bending.”

Runner up would be the entire “In the bathroom” chapter. I find a lot of humor value in offering a formula quantifying the effects of fiber as observed in human, uh, “output.” One better suited for public conversation is why orange juice (and many things) taste awful after you brush your teeth. Reason: sodium lauryl sulfate is added to many toothpastes as a foaming agent to disperse the paste. It temporarily disrupts sensitivity of sweet taste buds while increasing the bitter ones.[3] (It’s unpleasant, but does not cause cancer.[4])

Sources:

• [1] How to Fossilize Your Hamster (and other amazing experiments for the armchair scientist), Mick O’Hare. ISBN 9780805087703
• [2] “Fragmentation of rods by cascading cracks: why spaghetti does not break in half,” Basile Audoly and Sebastien Neukirch. Physical Review Letters 95, 095505 (2005). Movies available here.
• [3] “Surface active taste modifiers: a comparison of the physical and psychophysical properties of gynemic acid and sodium lauryl sulfate,” John DeSimone, Gerard Heck, Linda Bartoshuk, Chemical Senses 5:317-330, 1980.
• [4] “Sodium Lauryl Sulfate and Shampoo,” Snopes.com

### 1 thought on “Pasta puzzle”

1. This is a totally awesome post, all around. Thanks — I learned a new word! (And a bunch of other interesting stuff ðŸ™‚ — I never knew that about toothpaste; I figured it was just a perception (contrast with toothpaste flavor) effect!)