MIT mathematicians solve age-old spaghetti mystery | Hacker News Reader

MIT mathematicians solve age-old spaghetti mystery

news.mit.edu

171 pointsdenzil_correa35 comments

Odd, I saw that spaghetti phenomenon on smartereveryday just a few days ago, but it appears it was posted in 2014. Heh.

https://www.youtube.com/watch?v=ADD7QlQoFFI

Anyway, very cool.

I don't get how this is an interesting result. When you are allowed to change the applied stress (not just simple bending), getting it to break into just two pieces is easy.

By holding the spaghetti with two fingers at each end and applying compression together with bending, i.e. making the spaghetti look kinda like a sine wave from bottom to bottom, I can break spaghettis into just two pieces with success rate well above 50%. And I have confirmed with simple bending of shorter spaghettis that it's not just because of a shorter effective length.

Here's a picture of five spaghettis broken into just two pieces, along with one unbroken for comparison:

https://imgur.com/a/gOTiHG3

Now I gotta explain to my wife why there are broken spaghettis.

I find it more interesting that the casual behavior is to break into multiple pieces. Twisting is a neat way to add more input into a very simple system.

is that actually spaghetti though? it looks like linguine ...

According to the article, the model doesn't apply to linguini, so I'm not surprised it doesn't always break into 3+ pieces.

It's perfectly ordinary spaghetti (Barilla's no. 5 to be specific).

You make it sound like "changing the applied stress" is cheating, like they're equivocating on the problem. But the problem is just breaking spaghetti with your hand, by any means necessary for providing good entertainment. And challenging the unstated assumptions of a problem is often the most interesting way to solve it.

Anyway, sounds like it was interesting enough to make you do a bunch of experiments.

It's not that they're "cheating". It's just that many problems (like this one) are only difficult under some constraint. Lift that constraint, and it's easy (and therefore uninteresting).

I'm absolutely certain that Feynmann himself discovered the same thing as I did many decades ago, and that he discarded this "solution" because it was outside of the constraints that made the problem interesting.

After seeing this post, I dared my wife to do this. She simply applied stress carefully to spaghetti and broke it into two pieces.

>I don't get how this is an interesting result. When you are allowed to change the applied stress (not just simple bending), getting it to break into just two pieces is easy.

What's interesting is the exact way to achieve that. Unless someone knew that already...

Ah, cool! I also wonder if the twisting stress means that the noddle breaks before it is bent quite as far, which would also reduce the snap-back effect.

I also wonder if the twist-back breaks up the snap-back waves by redirecting their momentum.

Fun fact: when a cylindrical shaped object fractures from a twisting stress it leaves 45 degree break patterns. Try it with a pencil.

Depends on the material. Brittle materials will. Ductile materials tend to break on a 90 degree plane - https://goo.gl/images/QYMJmf

what are you the hulk? I can’t twist a Ticonderoga

I guess I've never tried doing it one noodle at a time or something, cause breaking a bunch of them at once results in them broken in two. Maybe they prevent each other from snapping back enough to break again?

I've never bothered to break them - why would you want tiny bits of spaghetti? Also wouldn't noodles be something completely different - like when I think "noodles" I think of an Asian dish, not a plate of spaghetti.

I find breaking in two as a bunch convenient since it makes it slightly easier to manage lengths. I do smaller for my daughter (2yo) since she struggles with scooping up the long ones on her own but is fine with smaller bits.

My 2.5 year old has the opposite issue; she learned the twist-the-fork method, which doesn't work well for short noodles.

(Although, to be honest, half the time she just uses her hands.)

It's called a "spaghetti noodle", like in the subheading of the article.

*in the US (but not necessarily in other English speaking countries)

Noodle is from a German root so not sure why you think of "noodles" as Asian.

I break spaghetti in half when I'm going to be stirring the cooked pasta into vegetables as opposed to serving a sauce on top of it.

Just looking around and this seems like it's a US-UK english difference: https://separatedbyacommonlanguage.blogspot.com/2015/08/nood...

And the reason I figured this would be weird is that long pasta is easy to eat with a fork. Probably not worth dwelling on this though as it's offtopic so people are downvoting :D

the noodles are something like 10-12" long so you don't really end up with tiny bits of spaghetti. It just makes it easier to cook in a smaller pot.

Take the bundle of spaghetti of spaghetti in one hand, place it vertically in the pot with boiling water, push down on the bundle from the top with your other hand. As the bottom part heats up and moistens the spaghetti will become immediately pliable and start going down and spreading out (in an appealingly geometric fashion), within a matter of seconds. You could cook 10" spaghetti, whole, in a 5" diameter pot with no problems.

Likely the way you are breaking them is different from what is described here. To do what is described in the article hold the spaghetti noodle by pressing either end to the index fingers of your hands and press inward to create a bowing effect, then continue to exert force until it snaps.

Probably what you're doing is just grabbing a handful closer to the center and folding the noodles.

You mean as a bundle? That makes sense, they'd dampen each others vibrations.

finally my code will be clean!

Now if only someone could explain why toppled smokestacks break into three pieces, my life would be complete :-)

I've been trying this all night, and I can't get any of them to break. Maybe I overcooked it.

Hm, it's interesting that this was unsolved for so long, given that any pasta chef can teach you how to break spaghetti, fettucini, etc. in two by twisting while bending. Very odd.

Not sure what the big deal is... this was solved back in 2005 in one of the top physics journals https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.95...

FTA:

"Feynman’s kitchen experiment remained unresolved until 2005, when physicists from France pieced together a theory to describe the forces at work when spaghetti — and any long, thin rod — is bent. They found that when a stick is bent evenly from both ends, it will break near the center, where it is most curved. This initial break triggers a “snap-back” effect and a bending wave, or vibration, that further fractures the stick. Their theory, which won the 2006 Ig Nobel Prize, seemed to solve Feynman’s puzzle. But a question remained: Could spaghetti ever be coerced to break in two?"

"Feynman’s kitchen experiment remained unresolved until 2005, when physicists from France pieced together a theory to describe the forces at work when spaghetti...But a question remained: Could spaghetti ever be coerced to break in two?"

gotta read the article man

That explains why the stresses present always split the tube in more than two pieces, but it does not prove that there is no possible way to get it to split in only two.

This paper demonstrates a way for it to only split in two.

And therefore is a significant advance over the original.

Understanding what the deal is starts with reading the article and not just the headline

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