Why spaghetti does not break in half

Why spaghetti does not break in half

Summary: Two French physicists say the answer is related to elastic waves travelling along the pasta when dry spaghetti is bent and suddenly released at one end.

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As we are Sunday, you might have more time to spend in your kitchen than during week days. So try a little experiment: take a dry spaghetti, and bend it until it cracks. How many pieces do you think you'll get? Two? Wrong. An uncooked spaghetti can break into three, seven or even ten pieces, but rarely two. It's even rumored that Nobel laureate and physicist Professor Richard Feynman has used lots of pasta to solve this mystery. But now, according to ABC Science Online in "Cracked! The secret life of spaghetti," two French physicists say the answer is related to elastic waves travelling along the pasta when dry spaghetti is bent and suddenly released at one end. And don't think this is a minor discovery: the researchers think their findings can be applied to civil engineering to make structures like buildings and bridges more stable.

Let's start with an introduction by ABC Science Online.

Physicists have settled one of science's more perplexing enigmas by explaining why uncooked spaghetti breaks into more than two pieces when you bend it.
French physicists Dr Basile Audoly and Dr Sébastien Neukirch say the answer is related to waves of vibration that pass through the pasta when dry spaghetti is bent and suddenly released at one end.

Below are two pictures of a dry spaghetti bent until it breaks in several pieces, before and after the breaking (Credit: Université Pierre et Marie Curie, Paris, France ).

Spaghetti bent just before cracking

Spahetti after cracking

These images have been extracted from a movie that you can see on a page maintained by the two French scientists, "How bent spaghetti break," along with other movies.

Of course, the physicists didn't only shot movies.

[After taking high-speed images of these broken spaghetti,] they applied the Kirchhoff equation, an equation that relates to how waves travel through an object that's put under stress. The researchers conclude that spaghetti fragmentation is caused by a burst of flexural, or elastic, waves that travel along the spaghetti after the initial break.

And they added that this "physical process of fragmentation is relevant to many areas of science and technology," a fact confirmed by Rod Cross, a professor of physics at the University of Sydney, Australia.

"If you can understand how spaghetti breaks you can understand how anything else breaks including a building an aeroplane or a car," he says. "Under impact they'll all vibrate and break. More to the point it can be a human leg, because if you whack a human leg it'll probably break in three or four bits as well for the same reason."

Oooch! What an example!

For more information, this research work has been published in Physical Review Letters under the name "Fragmentation of Rods by Cascading Cracks: Why Spaghetti Does Not Break in Half" (Volume 95, No. 9, article number 095505, August 26, 2005).

Here are two links to the abstract and to the full paper (PDF format, 5 pages, 366 KB).

Sources: Judy Skatssoon, Australian Broadcasting Corporation (ABC), Science Online, September 7, 2005; and various web sites

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  • Lets get CRACKIN!

    HAD to say it! ;)
    Roger Ramjet
    • RE: Why spaghetti does not break in half

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  • Cross-discipline lack of communication

    Anyone familiar with the tendancy for high-power hunting bows to break if the string is released witout an arrow could have told the spaghetti researches what the problem was.
    Henry Miller
    • Well...

      ...I hardly think French physicists and Ted Nugent have much interaction with each other. :)

      Carl Rapson
    • Having been in Archery

      I've always known that to be what happens but not the exact science behind it. People skilled in the science are good telling you why X happens when you do Y even though average people know it happens and make use of it or avoid it.
  • These scientific explanations are all very well

    but I think it is only fair to have some alternative theories so people can make up their own minds.

    Spaghetti breaks the way it does because the Flying Spaghetti Monster makes it break that way!

    See http://venganza.org/ for more explanation and remember to order your pirate costume.
    • Actually...

      ...I think it's a Microsoft plot to monopolize the spaghetti market. Just how, I'm not sure, but since spaghetti breaks don't follow common-sense rules, it must be somebody's fault. And we all know there's a Microsoft plot at the root of ALL things unexpected. :)

      Carl Rapson
      • Well it could be true

        think about the amount of spaghetti code in Microsoft products for example...and how often they break in unexpected ways.
  • I'm so glad this profound mystery has been cleared up

    Yay. Now we can get back to the all important "war on terra"..
    Jeff Spicoli
  • "Life and Death" is NO Trivial Subject!

    People who work with insulation fibres MMVF (Man Made Vitreous Fibres) are exposed to as many a eight fibres per cc. Eight million per cubic meter! Animal studies have revealed cancers, though the carcoinogenicity to humans is still a hot topic of debate. Spun glass wool is listed as A3 Animal Carcinogen, though the thicker continuous filament fibres used mainly in reinforcement are listed A4, Not Classifiable as a Human Carcinogen. OHSA has issued clarification that fibrous glass products MUST include a warning about the possible cancer hazzard from inhalation.

    So breaking spaghetti, may sound a trivial investigation worthy of an Ig Nobel Prize, but the subject is far from trivial in practice!
    Brother Martin de Porres
  • RE: Why spaghetti does not break in half

    it is because of vibration
    ching cute