# Pi Day: Why we celebrate 3.14...

Pi Day: March 14 is Pi Day, where celebrants contemplate the world's most famous irrational number. Or just eat some pie.

It's March 14. Happy Pi Day!

As nerd holidays go, Pi Day – or 3/14, get it? – ranks near the top, right up there with Geek Pride Day (May 25), International Talk Like a Pirate Day (Sept. 19), and Star Wars Day (May the 4th be with you). It also doesn't hurt that March 14 is Albert Einstein's birthday.

While most of us are content celebrating the world's most famous mathematical constant to its second decimal place, the most pi-ous among us were out of bed at (or stayed up until) 1:59 this morning, waiting to 26 seconds past the minute to take the first chomp into their homophonous baked confection of choice.

Those who don't write their dates in a month/day format – that is, just about everyone on Earth – will have to wait until July 22 (22/7) for Pi Approximation Day to celebrate the ratio of a circle's circumference to its diameter, more or less.

For all its popularity, pi isn't everyone's favorite irrational number for calculating circles. Self-described "mathematical propagandist" Michael Hartl argues that circles are more "naturally" defined by their radius, not their diameter. A more elegant circle constant, Hartl argues, would be the circumference divided by the radius – pi multiplied by 2, or about 6.28. Hartl calls this constant "tau," after the 19th letter of the Greek alphabet, and he hopes that more people will celebrate Tau Day on June 28. We suspect that this is an elaborate ruse to get people to eat twice as much pie.

There are, of course, other ways to celebrate this transcendental number that don't involve stuffing one's face. One could, for instance, turn it into a song. Musician Michael Blake performed this one-man symphonic ode to pi by assigning notes and chords to each digit, and then playing it to 31 decimal places on ten different instruments. The result is a catchy yet haunting tune that is bound to top the pi charts:

How do we explain pi's enduring popularity? After all, there are lots of important mathematical constants, but you don't see people celebrating Euler's number every Feb. 72nd, or thereabouts. It could be that pi, in some sense, encapsulates humanity's quest for scientific knowledge. To calculate pi is to take the simplest of concepts – a circle – and reveal the limitless complexity that lies beneath it. Like the progress of science, pi never stops, and it never repeats. Computer scientists in the US and Japan have calculated it to five trillion digits, with no end in sight. Precision, pi reminds us, does not always lead to perfection.