Skip Ad
Ad Loading...



Physicist Aaron Santos of Simpson College in Indianola is known for crunching the numbers on "Fermi problems" -- use good math to calculate reasonable estimates for what might seem like impossibly large or complex problems.

The basic available math on Santa Claus adds up to eight tiny reindeer, plus or minus Rudolph and his bulbous red nose.

Yes, Santa insists that he double-checks his list before he comes to town. But for some reason he never provides a precise tally of the number of "naughty" and "nice" kids — or what percentage of the nice list might be dominated by children of the wealthy and powerful who have the means to curry favor with Santa's top directors. (Alas, Santa ignores all our open-records requests.)

If we lack proper documentation on Santa, at least we have the well-ordered, detailed brain of a physicist such as Aaron Santos of Simpson College in Indianola. At the request of the Canadian radio show "Science for the People" he has calculated some of the statistical difficulties of Christmas gift delivery.

Santos, 34, is wrapping up his first semester as an assistant physics professor at Simpson. He describes himself as a "physicist who likes solving geeky Fermi problems."

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."

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."

Santos more or less has made Fermi problems a signature with his books "How Many Licks?: Or, How to Estimate Damn Near Anything" and "Ballparking: Practical Math for Impractical Sports Questions." (The next volume he'd like to write would cater to science-fiction fans: "The Math of Khan.")

But he's trying to make a serious point with his populist math.

"As a country we're very scientifically illiterate, and even more so, we're math illiterate," he said.

"And that becomes a huge problem when people can't balance their checkbook, or they don't know what policies to vote for because they hear all these big numbers (such as) a trillion-dollar national debt."

So here's some of the Santa math newly computed by Santos:

? How long would it take Santa to deliver presents to every child in the world?

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.

? How much energy would the reindeer need for deliveries?

Just to overcome the drag force of traveling at such extreme speed requires 6x1028 joules —or the same amount of energy that could power the entire United States for 4.5 billion years.

? What's the weight of Santa's sack of gifts?

Eighteen million tons, or the heft of about 100 Empire State Buildings.

? How many elves are needed to manufacture all the presents within a year?

About 1 million: Each elf manufactures 10 toys per day, 365 days per year (because they're not allowed to unionize).

? How many calories would Santa consume on Christmas Eve, and what would he need to do to shed those holiday pounds?

Assuming one cookie per child (3.5 billion), Santa would consume about 350 billion calories. He would need to spend 1.5 billion years on a stair-climber to burn off the extra fat from his "bowl full of jelly."

? How much would the reindeer need to eat?

Assuming a North Pole-friendly diet of candy canes, the reindeer would need to eat a gob of candy canes about the size of Pluto.

? What sort of mess would the reindeer leave behind? (Put less delicately, how much would they poop?)

A 50-kilometer-deep layer of reindeer dung would cover the earth after Christmas — somewhat hampering the charm of opening all the presents.

That last bit, Santos told "Science for the People" host Desiree Schell, might be the weirdest Fermi problem that has ever been posed to him.

When Simpson senior Mike Henry sat down for the first day of thermal dynamics class earlier this fall, the first question Santos asked him and his classmates was the classic Fermi problem, "How many piano tuners are there in Chicago?" (A typical answer: 125.)

Or what about the probability of a rocket landing on a house if you happen to work for NASA?

"There are practical reasons for doing this," Santos said. "It's not all reindeer poop."

Consider how Henry shops for his peanut butter: The math and physics major isn't content with the price-per-ounce displayed on store shelves as an antidote to brands that love to trick buyers with fancy packaging and sale prices. Instead, he compares nutrition labels to compute his cost per calorie in search of the best value.

"I like to make data-driven solutions," Henry explained, "instead of just doing something because of what I've always done in the past."

Talking to the likes of Henry and Santos made me think that most of us are trapped in a "Matrix" construct, and only these physicists have the mental tools to navigate reality.

There is a case to be made for Santa as the original gateway to scientific curiosity.

"As you know that Santa's not there, all of a sudden you think, 'Wait, what else have they been lying about?' " said Santos, who grew up in New Bedford, Mass., waiting for Santa to shimmy down the chimney. "And to a certain extent that might be a good thing, because I think that gives children a healthy skepticism."

Along with all the seasonal Santa chatter, a clip of a Carl Sagan interview with Charlie Rose, recorded months before the astronomer died in December 1996, has been making the rounds online this week. It has been cast as a prescient warning.

"Science ... is a way of skeptically interrogating the universe with a fine understanding of human fallibility," Sagan says.

"If we are not able to ask skeptical questions … of those in authority, then we're up for grabs for the next charlatan — political or religious — who comes ambling along."

So as a columnist rather than a physicist, this is my specialty: I've demonstrated how a strong democracy relies on the ability to calculate the amount of reindeer poop.

Kyle Munson can be reached at 515-284-8124 or See more of his columns, blog posts and video at Connect with him on Facebook (Kyle Munson's Iowa) and Twitter (@KyleMunson).

Read or Share this story: