Pi is the mathematical constant that represents the ratio of a circle’s circumference to its diameter. Seeing how every mathematical equation uses a circle’s radius, not its diameter, it seems odd that the most important number in history would be developed with a diameter. It’s not odd, it’s just wrong. The correct constant is “tau”, or for the uneducated, 2pi. Tau is the ratio of a circle’s circumference to its radius, and the most used constant in math and physics. Did you ever notice how every important equation uses 2pi? Probably not, but it’s true.
So please stop celebrating Pi Day, and start celebrating the correct holiday on June 28th, Tau day (6.28). Check out Michael Hartl’s website which contains all the proof you need. http://tauday.com/tau-manifesto