My birthday is also Pi Day, named after the mathematical constant that, unlike myself, has been proven to be irrational. I am only theoretically irrational.
Google celebrates 6 applications of pi: (1) πr2 (area of a circle) formula, (2) C = 2πr (circumference of a circle), (3) V = 4⁄3 πr3 (volume of a sphere), (4) V = πr2h (volume of a cylinder), (5) the period of the sin function, and (6) Archimedes’ trapping of Pi between 223/71 and 22/7.
Sometimes I think the world as we experience it is just the outcome of a single expressed variable in the universe, propagated across every symmetry, and the existence of this constant Pi so prevalent in figures of symmetry is just a symptom of this.
But then I think, I want to be a Google doodler. Perhaps the most awesome job ever: http://news.cnet.com/8301-13772_3-20014631-52.html