Tau Day Approaches! No Pi(e) for you!

[Bells]

http://tauday.com/

So, apparently Pi is wrong... ?

Warning, we're about to get into really... really... nerdy stuff. Full Math Gear on people! we're going in...

March 14, or 3/14, is known as “Pi Day” because of its resemblance to the first three digits in the decimal expansion of ? (pi), which is defined as the ratio of a circle’s circumference to its diameter:

?=CD=3.14…

As the “circle constant”, ? is the object of virtually unlimited adulation, so you are probably under the impression that ? is a particularly important number. I am sorry to report that you have been misinformed.

The true circle constant is the ratio of a circle’s circumference to its radius, not to its diameter. This number, called ? (tau), is equal to 2?, so ? is 12?—and March 14 is thus Half Tau Day. (Of course, since ?=6.28…, June 28, or 6/28, is Tau Day itself.) Although it is of great historical importance, the mathematical significance of ? is simply that it is one-half ?.

But how can this be? What about trigonometry? What about Euler’s identity? What about ?r2? Can ? really be wrong? All your questions and more are answered here, in an article called The Tau Manifesto.

Also this

So, if in the coming week you hear a lot of geeks talking about Tau... now you know!