# Happy Tau Day 2011! The Pie is a Lie

This is it, folks! It’s the first anniversary of Tau Day, the “time to celebrate and rejoice in all things mathematical and true.” Every year, geeks, nerds, and ~~pie~~ pi lovers celebrate Pi Day on March 14. Year in and year out, students learn the value of pi – both in theoretical and practical aspects. 3.1416… – who is not familiar with the number?

Behind the scenes, however, there is another number that we must pay attention to. Earlier this year, I discovered the Tau Manifesto, courtesy of math goddess (I’ve taken the liberty to call her this) Vi Hart. She made a video explaining why Pi is wrong. Why it makes things so confusing. Why we need to have another number that is more reflective of reality. Facts and very convincing arguments aside, the video is wonderfully made, and you just can’t help but get enthralled by that pie! Here, watch it for yourself.

As I have said before, I don’t think that ? is wrong – not at all! But I do subscribe to the idea that ? (tau) just might be a better number. In fact, the proponents of Tau Day clarify that ? is not factually incorrect, only that it “is a confusing and unnatural choice for the circle constant.”

The argument of Michael Hartl of the Tau Manifesto ((The Tau Manifesto)) fame can be summed up as:

- The constant ? is the ratio of a circle’s circumference (C) to its diameter (D). Anyone who has had even the most basic of math classes would know that the diameter is 2?; therefore ? = C/D.
- The true circle constant is the ratio of a circle’s circumference (C) to its radius (R). This constant is ? (tau) and it is equal to 2?!

Indeed, if you think about it the removal of the multiplier to define the circle constant makes things simpler. Now there is deeper math that surrounds all this – math geeks can read the manifesto in the link above.

What remains to be done now is to celebrate Tau Day, since it is June 28. ((So can you tell me why this is the designated Tau Day?)) So how can one celebrate Tau Day? If you’re in the vicinity of Caltech in Pasadena, head on over there at around 8 in the evening for a solid evening of everything tau. If that is not your thing, or logistics simply do not allow it, then I suggest baking/buying two of your favorite pies and enjoying them this evening. After all,** ?=2?**. Now I’m starting to really like this constant!

How about you? Are you willing to trade in Pi Day for Tau Day?