Getting into the festive mood can be quite a challenge if you’re stuck with a big mess of Christmas lights. It seems that no matter how neatly you put them away after the holidays, they somehow end up in a tangled mess the next year. It’s confounding, and it turns out, there are scientific reasons for why it happens.
Back in 2007, some scientists did a study and published it in a journal called Proceedings of the National Academy of Sciences (PNAS). They wanted to figure out why these knots happen. In order to cut through this knotty conundrum, they put different lengths of string inside a box and shook it hard, like clothes in a washing machine. They did this more than 3,400 times and what they saw was that knots started to form within just a few seconds of shaking the box. Moreover, they found more than 120 different kinds of knots.
“It didn’t take long at all for those knots to show up – maybe about 10 seconds. We were surprised by that,” said one of the scientists, Douglas Smith, who works at the University of California, San Diego (UCSD). “We immediately started seeing these complicated knots begin to form. It was all very rapid.”
A knotty problem
They also noticed that the length of the string made a difference. As the string got longer (the longest they used was about 4.6 meters), it was more likely to get tangled up. The type of material the string was made from mattered too. Strings that could bend easily got tangled more than stiff ones, according to their study.
But here’s the main thing: whether the ends of the string were hanging loose or not had a big effect. If the ends were free to move around, they’d get tangled up more.
“The ends are really what get a knot to form,” Dorian Raymer, the study’s lead author and a former UCSD student who now works as a consulting systems engineer, told Live Science. “Sailors probably know it best, that you have to control what the ends [of a rope] are doing to avoid knots. Otherwise, the ends can move over or under other sections of the string, which will ultimately lead to knots.”
Christmas lights are worse than string
And when it comes to Christmas lights, having lots of bulbs sticking out from the wire just gives more chances for them to get tangled.
“I think personally from my own experience using Christmas lights, it’s more of the nubs of lights that stick out of the side of the cord that create a lot of friction and get caught on each other,” Smith said. “It’s even worse than a regular piece of string.”
So, what can you do to stop these knots from ruining your holiday fun? One trick is to wind the lights around a flat piece of cardboard before you put them away in a box.
“Make sure you tape down the ends of the lights onto the cardboard,” advised Raymer. “This way, they can’t move around, and they won’t get tangled up.”
Smith agreed, saying, “Or you could get someone else to help you hang them up.”