As you know, many people celebrate PI Day by having
Pi pie. (See my post on Pi Day, here.) But there is a rival movement afoot to replace Pi Day with Tau Day (and indeed, to replace Pi with Tau as a standard).
Pi, of course, is the ratio of a circle’s circumference to its diameter (3.14159265…), currently celebrated on March 14. Tau, or τ, is the ratio of a circle’s circumference to its radius. Thus it is twice the amount of π (6.28318530…). (Hence the celebration on June 28.)
Mathematicians are divided on the issue, but to me it makes infinite [sic] sense to celebrate Tau Day, because it implies TWO pieces of pie. TWO pies. This sounds like a good thing.
Two Times PI:
Two of the 2012 winners from the yearly Pi Day contest sponsored by the Serious Eats Blog: