Today is “Pi Day,” the 14th day of the 3rd month (3.14). Not only that, it is “Super Pi Day,” with the rest of the date giving the next two numbers: 3.14.15. Pi is the ratio of the circumference of a circle to its diameter. Though circles are everywhere, their numeric ratios can never be exact. The mysterious number represented by the Greek letter π has been proven to be an “irrational number,” one which has an infinite number of non-repeating decimals. And, yet, the ratio has to be used in all kinds of common calculations, from figuring the area of a circle to analyzing subatomic and astronomical phenomena.
After the jump, an excerpt and a link to an essay on π and pi day by Cornell mathematicisn Tara S. Holm. Do go to the link for an account of the history of our knowledge of the concept, including a government attempt to regularize it at 3.2 by passing a law. My favorite part is how Prof. Holm is celebrating the day: Getting her family together at 9:26 and 53 seconds (the next five numbers) and eating a piece of pie. (more…)