Santa Math

A professor’s charming—and slightly unhinged—explanation for how St. Nick pulls off his annual gift delivery.

Santa’s journey to every coal-fearing child in one night is impossible—or is it? Larry Silverberg of North Carolina State University asked himself and his students this question. In the video above, we run through his answer, which involves relativity, a toy-making machine, and a jet-propelled sleigh.

Also in Slate: Santa Claus’ Magic Sleigh Ride is Highly Inefficient. So We Made Him a Better Itinerary.