We don’t need to tell you guys how annoying it is to find your headphones tangled every. single. time. you take them out of your bag. We know you know.
But what you might not be aware of is the fact scientists have actually studied the issue, and identified the factors that lead to knotting.
It turns out, it all comes down to the length of the wire and the amount of “agitation” it's subjected to, as Jim Edwards reports for Business Insider.
When these two factors are plotted against each other, scientists are able to see a curve that reveals the likelihood of headphones getting tangled up.
A  paper titled “Spontaneous knotting of an agitated string” by Dorian M. Raymer and Douglas E. Smith of the University of California at San Diego Department of Physics demonstrated this phenomenon: It revealed that a cord of less than 46 centimeters in length (about 1 foot six inches) will almost never tangle itself when sealed inside a rotating box for a period. But between 46 centimeters and 150 centimeters (about five feet), the probability of a knot forming rises dramatically. With a cord longer than that, the probability of a knot forming reaches a plateau of 50%. It turns out that the odds of getting a knot do not go higher because the cord wedges itself inside the shape of the box and that prevents further tangles from forming. Raymer and Smith performed 3,415 trials to demonstrate this.
The resulting graph looks something like this.
Now, unfortunately, Apple’s headphones are right in that tangle-prone sweet spot, at 139-cm-long. That means that whenever you put your headphones in your bag, the odds of them tangling up is 50% - in fact, it’s probably even higher when you factor in the Y-shape of the chord, which this research did not.
But perhaps the most interesting part of it all is that the study also included a schematic illustration to prove that headphones can spontaneously knot themselves as a result of physics - no matter how neatly you put them away.
This knowledge may not make the (first world) problem any less frustrating, but next time you're getting all worked up over a tangled chord, stop and think about the science.