A physicist from England has a theory for how Santa fits down chimneys across the world.
Mr. Claus has to travel at 6.2 million miles-per-hour to make it to every kid’s house, and according to Einstein’s theory of relativity, things moving at high speeds become compressed.
The theory would easily explain why no one ever catches a glimpse of him. At those speeds, he would become invisible to the human eye.
Source: Daily Mail