Have you made plans for Pi Day? Do you even know what Pi Day is?
As the name implies, it’s a day to celebrate 3.14. The Exploratorium, a San Francisco museum, hosts an annual homage to the number that never knows when to stop. In fact, the museum claims to have invented this celebration 21 years ago. It has since spread across the country (among mathletes, at least).
We spoke to Larry Shaw, technical curator emeritus, who takes partial credit (or blame) for Pi Day’s conception.
Why celebrate Pi Day?
It’s a transcendental number.
Um, what does that mean?
You have integers. You have fractions, which are ratios of integers. And then you have things like the square root of two, which is an irrational number. It cannot be expressed as a ratio of two numbers.
Pi is definitely irrational. It is also transcendental.
Do go on.
Basically no matter what you do with pi [or any transcendental number], you never get back to the integer realm. Apparently there are a lot more transcendental numbers than fractions or merely irrational numbers.
And why is that so transcendental?
To have the ratio of the circumference and [the] diameter of a circle be transcendental means there’s nothing you can do to make it even, or ever come out. It’s indicative, I think, in a bizarre way of what the physical universe is about. It is not as determinant as science would like to have it, but nobody knows why.
Can you restate that for the non-math people among us?
I just think it’s intriguing that this ratio between a circle’s dimensions should not be something you can pin down. That’s sort of a mystery.
Is there a life lesson to be learned from that?
I don’t know.
And how far out has pi been calculated?
I don’t know the current number of digits. Last I heard it was 1.2 trillion.
Do other numbers have holidays?
We just had Square Root Day, which was 3/3/09.
I guess that doesn’t happen very often?
Another one was 2/2/04.
Is Pi Day celebrated around the world?
With the way people write the dates in Europe [date first, then month], you can’t have Pi Day. You can have Pi Approximation Day, which is the 22nd of July—22/7. [Note: that’s because 22 divided by 7 yields an approximation of the value of pi.]
I understand that devotees of pi memorize many of its digits.
Oh, yeah, yeah—there’s a club who[se members] have memorized it to 100 digits.
How do you do that?
Just work on it.
Have you tried?
I haven’t. We have a parade [at the Exploratorium] where we give people a yardstick that has a pie plate stapled to its top, with a digit of pi on it. They line up in appropriate order and march [through] the museum. I have a boombox with a computer voice singing [the digits] of pi to “Pomp and Circumstance”: (sings) Three point one four nine five …
It turns out that March 14, aka Pi Day, is more than just Pi Day.
My daughter said, “That’s Einstein’s birthday,” and it is. So now [at the museum] we march around the pi shrine and sing happy birthday to Albert.
Are there any other ways to celebrate pi?
One always looks for patterns in pi, but nobody’s found any yet. There is a website where you can find where your birthday first occurs in pi.
[At this point in the interview, he hands his cell phone over to Ron Hipschman, who says he’s a systems administrator at the museum, Shaw’s sidekick (only without a cape), and, according to his business card, “a loose cannon.”]
Not everyone is a fan of many digits.
Hipschman: The state of Indiana once tried to legislate the value of pi to be 3.2.
That would be a mistake, I assume.
With 39 digits of pi, if you knew the diameter of the universe, you could measure the circumference of the universe to the accuracy of the diameter of a proton.
I’m going to pretend I understood what you just said. But we don’t know the diameter of the universe, do we?
Assume it’s very, very large.
And could you remind me of that formula? I think I left my math textbook home.
Circumference is equal to pi times the diameter of the circle.
The most important question about Pi Day: Will you and Larry be celebrating with fruit pie or pizza pie?
We’re going to have fruit pie this time, but at the Exploratorium we will have pizza dough so visitors will be able to practice tossing pizza dough.