Science World Blog Why do my earphones tangle so much?
Why do my earphones tangle so much?
Last Updated (Sunday, 22 January 2012 17:55) Written by Raymond Nakamura
Listening to podcasts has transformed the time I spend washing dishes, exercising, and watching my daughter play in the schoolyard. But why do my earphones get tangled so easily?
Entropy
In the Ontario Science Centre podcast, the Redshift report (episode 32), they explained that the entanglement was an example of entropy in statistical mechanics, that there are way more ways you don't want something than you do. If you wrap up or clip your cord, you are adding energy to make the system more orderly. But this is too much trouble for me and it seems like it could damage the wiring inside more easily.
Knotty is Knice
Enter Dorian Raymer, an undergrad at the University of California San Diego who was curious about the mathematics of knots and a biophysics professor named Doug Smith who suggested Raymer take an experimental approach to the question. They won an Ignobel Prize for their study on how knots form when you put a cord in a spinning box or as they called it, "Spontaneous knotting of an agitated string."
In Raymer's sometimes awkward talk on the paper, he mentions factors affecting the chance of forming a knot in a cord bouncing around in a box. They were interested in questions like knot formation in DNA and umbilical cords, but the results have clear application to understanding the earphone phenomenon. Having three strands in the earphone system and weight of the ear buds at the ends could further increase the odds of entanglement.
Length
The cord had to be at least 46 centimeters to form a knot. This must be why you never get knots in spaghetti. And if you had some way have using shorter earphone cables, it could reduce the chance of knots.
Flexibility
More flexible materials are more prone to having knots. So if you could make the earphone cables stiffer, you could reduce the chance of knots. One product I came across does this by adding springs onto the branch cables.
Rotation Rate
The more they get tumbled, the better chance they have of getting tangled. This made me realize that it might be better to keep the earphones in my breast pocket instead of my pants pocket.
Number of Rotations
The more rotations, the higher probability of getting a knot. So if you leave your earphones jostling around for longer, the more likely they will get tangled.
Box Size
A bigger box resulted in more knots. So if you leave your earphones in a smaller pocket instead of a big bag, you might have a better chance of not getting knotted.
Raymer ran over 3000 tests. If you add your observations of earphone behaviours in the comments, we could test these parameters. Or, if you are more motivated by money than pure knowledge, people are starting to sell various solutions and analyzing these parameters might help you invent the next big thing.
Comments
Other than 'The Redshift Report', do you know of any other good science podcasts, Ray?
As a climber it's uncanny, yet very disappointing how knots can end up in the middle of the rope.
Another example of putting a string in a rotating box may be vortexing DNA, which I frequently do in the lab. This is not recommended though for long strands of DNA as they can shear. Maybe this is the magical length threshold where DNA can start to form knots?
Do you really think a rotating box is a good model for a pocket? The shape, friction and pattern of movement seem a poor match to me. Maybe I'm just old, but my pockets don't tumble anymore, so letting the heavier part of the earbuds settle to the bottom (where they want to be) essentially eliminates the opportunity for them to pass through various cable loops on the way down.
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