Cleared for takeoff how Santas sleigh takes to the skies

Santa Claus’s reindeer will be in need of a good rest after their Christmas Eve capers based on a study by fourth year Master's students from the Department of Physics and Astronomy, who have estimated the velocity required to provide enough lift force to get his sleigh to take flight given the large mass of presents in tow.

Santa is expected to visit every household delivering presents by travelling speedily through the sky on his sleigh during Christmas Eve. In order to take off with sacks of presents on board his sleigh, the students worked out the velocity needed to provide enough lift force, concluding that it would be around 0.76% of the speed of light.

A sleepy reindeer, possibly tired after helping Santa on his Christmas journey

To calculate this, the study assumed that everyone on Earth receives one present and that each present has a mass of 0.5kg to create an average. The current population at the time of the study was recorded by the students as being 7,380,707,146, meaning that Santa would need to be carrying a large number of parcels to satisfy demand - a feat a little Christmas magic could aid in.

The students then calculated the small amount of time dilation and length contraction of Santa and his sleigh given he was travelling at this speed – although feasibly he could travel even faster.

The students estimate that, given Santa is travelling at 0.76% of the speed of light for 12 hours on one day of every year, over all the years of Santa delivering presents since his origin in 1821, he would have reduced his age by 242 seconds.

Because the velocity affects the length of the sleigh the students then reworked their initial estimate for the lift using a more sophisticated model and recalculated the relationship between the lift force and the velocity – concluding that the lift force goes to zero as the velocity approaches the speed of light.