Researchers at the University of Exeter have revealed a scientific explanation on how the infamous Santa Claus move from chimney to chimney without being spotted or heard by expecting children.

Their findings, presented at Science of Christmas Festival, showed that the Albert Einstein's theory of relativity could easily explain how Santa Claus could deliver gifts to more than 700 million children in one night without being seen or heard.

"Visiting around 700 million children in 31 hours would mean he would have to travel at 10 million kilometers an hour if he is to deliver presents to every child," said Dr. Katy Sheen, a physicist in the Geography department at the University of Exeter, in a press release. "How does Santa manage to reach these phenomenal speeds? Well that's magic! 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!"

According to Dr. Sheen's calculations, Rudolph and the gang need carry Santa around at about 10 million kilometers per hour in order to deliver the presents to more than 700 million children in 31 hours, considering world time zones. Santa is often featured as an old man with a huge white beard and large stature. However, due to the high speed of his travel, Santa could actually shrink, or get thinner, making it possible for Santa to fit into chimneys.

Theory of relativity could also explain why the children expecting Santa Claus at night rarely catch a glimpse of the fat man. The researchers noted that the ability of Santa to be undetectable is due to the so-called Doppler Effect. Traveling at more than 200,000 times faster than the world's fastest man, Usain Bolt, the Doppler Effect would change Santa's color, turning him from red to green until he finally disappears at greater speed. The high traveling speed of Santa would also silence his approach and departure.

Dr. Sheen explained that the high speed of Santa's sleigh could squash the light waves that are being released. On the other hand, the sound created by Santa speeding through the skies would be too high for human hearing range, making it appear like completely silent. However, Santa's ride could create a sonic boom as they break the speed of sound.

The scientific explanation for the stealth delivery of Santa Claus is made to present science and physics interesting to children. Dr. Sheen has no plans to publish her calculations to a peer-review journal. She clarified that her calculations were only made to make physics interesting.