If Santa flew fast enough to visit every single child in the world on Christmas Eve, he'd burst into flames. And also basically liquify.

That's just one of the great holiday science facts in the latest episode of "It's Okay To Be Smart." But my favorite bit is at the beginning of the video: Why do Christmas lights always get tangled?

Blame it on the second law of thermodynamics. We live in a universe that tends towards chaos. It's easier for things to fall apart than it is for them to stay together.

But if the concept of entropy has always boggled your mind a bit, think of it this way: There's only one configuration for this string of Christmas tree lights that keeps them from being tangled. Every other possible twist and bend of the string leads to a tangle. So in a world of infinite possibilities for how your string of lights will shift around in storage, it's just infinitely more likely that the lights will move in a way that leaves them messy.

And once one knot forms, it's unlikely to un-form. It's probably just going to lead to more knots.

Knot formation becomes more likely the longer a string gets, so think twice about trying to get a strand long enough to wrap your entire tree in one go.

In the end, it's just a tragic, universal truth: As long, thin, flexible strands, Christmas lights are pretty much designed to get tangled up in each other.