John Metcalfe

People who are very enthusiastic about irrational numbers, it turns out.

Everybody's got to have a hobby. For the fans of Pi Day, which occurs every March 14, it's the fanatical appreciation of what's arguably the universe's most intriguing number: 3.14159265359-et cetera, the ratio of a circle's circumference to its diameter. But you remembered that from school, right?

Euler's number? It can eat horse manure. The golden ratio? Don't make me fog my TI-84 graphing calculator's screen with uncontrollable chortling. When it comes to the awesomeness of irrational numbers, pi is king of them all – at least according to the people milling around on Thursday for the Pi Day fest at San Francisco's Exploratorium.

This genial and in some cases quite fashionably dressed crowd had gathered for an afternoon of pi lectures, pie eating and even a marriage sanctified by the "Prince of Pi" himself, Larry Shaw, who helped invent the quirky holiday 25 years ago. Spirits were high despite cloudy weather postponing the "world's largest ephemeral installation of pi" – a depiction of the first thousand digits of the mathematical constant sprayed out by a sky-writing team of stunt pilots. But we can imagine what it would've looked like, thanks to these photos of the "Pi in the Sky" event from 2012:

(ISHKY Studios)

This afternoon, I hit the streets to get some answers to burning questions from the patrons of Pi Day: Did you take off work to attend this? How many decimals of pi can you recite? If you love pi so much, would you marry it? Here's what they had to say.


Lanie ordered her custom pi t-shirt online. She's a pro.

Lanie: "I've been a pi enthusiast for 10 years now. I always celebrate Pi Day – little parties where we bake pie, recite the digits of pi, wear pi shirts. It's me and some friends being like, It's Friday! Let's eat and be merry and celebrate the wonderfulness of pi."

So if you weren't here today, you'd be...

"I  probably would be at home, baking a pie."


What are those signs you're holding?

Candy: "Isn't that some ephemera? They gave them out to people who were part of a pi parade [in which folks lined up in proper numerical order of pi's digits]. He was 39, and I was 40.... We came here today because it's actually my birthday."

So does that yardstick count as your present?

Paul: "Hmmm...." (Looking like he's considering it.)

Candy: "That worked out for you, didn't it?"


How's it going?

"I was really looking forward to the sky writing, but it was cancelled. It's a total drag."

You have a lot of tattoos – is there a pi somewhere on your body?

"No. The closest thing, I guess, would be a schematic drawing. It's a Tesla coil."


Any deep thoughts on pi?

Jill: "Anything that's a constant is interesting. So much in life is changing. It's unusual to find something that stays the same."


Rob is an Exploratorium "Explainer," meaning it's his job to explain sciencey stuff to children on field trips. So Rob, can you tell us what's so cool about pi?

Rob: (Silence.) "I guess just the ubiquitous nature of it? It allows us to participate in the most ubiquitous natural form around, the circle." (Looks off at a man in the crowd.) "That's the guy who invented Pi Day." (Pulls up the man's entry on Wikipedia.) "Look, he's wearing the same shirt."


Larry didn't have much time to talk, because he was about to officiate a marriage happening on the "Pi Shrine," a metal plaque on the sidewalk imprinted with pi information. The retired physicist, once a senior media specialist at the Exploratorium, said this is actually the second wedding he's officiated. He once did a pirate-themed wedding for somebody who was really into Dungeons & Dragons; he recalls that a guest pretended to rob the ring bearer, shouting, "It's all booty for me!"

The happy couple. You can't see it, but they were reading out of a copy of Dr. Seuss' Oh, the Places You'll Go!

Random dude in the crowd: "Getting married at Pi Day is becoming like a tradition. It has to happen. If nobody stands up, we have to draw straws among the Explainers."

About the Author

John Metcalfe
John Metcalfe

John Metcalfe is CityLab’s Bay Area bureau chief, based in Oakland. His coverage focuses on climate change and the science of cities.

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