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December 24 is a big night for Kris Kringle. He has to hoof it around the world, and be pretty speedy about it, in order to visit all the children in a single night. How quickly must he travel? Try six million miles per hour, according to Dr. Katy Sheen, a physicist at the University of Exeter. With a little help from Einstein's theory of relativity, Sheen was able to explain many of Santa's mysteries, like why hasn't some curious child caught him on their iPhone yet? And how does he fit down the chimney if he's so pleasantly plump? "Some strange things happen when you start to travel that fast. Firstly, time slows down," Sheen explained in a press release. "Second, Santa gets squished which means that he can fit down a chimney more easily."

Because science plays a part in even the most magical moments. What better way to teach your kids about physics than using jolly old St. Nick? Plus, you've finally got an answer to the questions of all those Santa skeptics out there. Of course, you'll still have to suspend some disbelief, Sheen explains. "How does Santa manage to reach these phenomenal speeds? Well that's magic!" she said. "However, he would certainly need a lot of fuel - so don't forget his glass of sherry, a mince pie or two and some carrots for the reindeer!"

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