• How long would it take Santa to deliver presents to every child in the world?Now, the more important message in this article is not really about Santa, or his reindeer, or even the problem being tackled. Rather, it is one aspect of science that is often neglected and what many in the general public aren't able to do. It was described as the "Fermi problem".
Considering the 3.5 billion children on Earth (without regard to religion) and 500 million square kilometers of the Earth’s surface, Santa would need 14 years if he traveled at the speed of our fastest jets (Mach 10). Santa could finish the job in about 80 minutes assuming he travels at light speed — a timeline that even Amazon’s Jeff Bezos with his experimental army of delivery drones would find difficult to match.
For non-geeks: Enrico Fermi was the landmark Italian-American physicist of the 20th century who discovered nuclear fission. “Fermi problems” are (in the succinct words of Wikipedia) “justified guesses about quantities that seem impossible to compute given limited available information.”This is often a crucial step whenever we think of something, especially when it is new. We make gross estimate of what the result should be, so that we know that at the very least, it can't be either bigger, or smaller, than such-and-such a number. But this requires, as you can see, a QUANTITATIVE understanding of it. You make an estimate and produce a value, rather than just a qualitative idea. It tells you of the SCALE of things.
In other words, this is the wacky trivia that physicists love to debate after a couple of glasses of spiked eggnog. Santos calls them “back-of-the-envelope questions” and scratches out a typical solution within 5 or 10 minutes. He loves “the idea of being able to come up with something using as little information as possible.”
“It doesn’t tell you what the answer is,” he clarified of this more stringent estimation game. “But it tells you what the answer can’t be.”
For many people, this is what they do not have a feel for.