With the help of engineering professor Larry Silverberg, Abigail Wise worked out the physics of Santa's delivery schedule:
Santa has to deliver gifts to around 200 million children spread over 200 million square miles. Because each household has 2.67 children, there are about 75 million homes to visit and the average distance between homes is about 1.63 miles, Santa needs to cover 122 million miles.
To cover that distance in 24 hours on Christmas, Mr. Claus’s sleigh would need to travel at a whopping average speed of 5,083,000 mph. Silverberg argues that the feat is possible because the sleigh would have to travel 130 times more slowly than the speed of light, which is 300 million meters per second, or 669,600,000 mph. Because something already moves that quickly, it would be difficult, but not impossible, for Santa to travel at 5,083,000 mph.