How-To Geek

Happy Tau Day! (Or: How Some Mathematicians Think We Should Retire Pi) [Video]

When you were in school you learned all about Pi and its relationship to circles and turn-based geometry. Some mathematicians are rallying for a new lesson, on about Tau.

Michael Hartl is a mathematician on a mission, a mission to get people away from using Pi and to start using Tau. His manifesto opens:

Welcome to The Tau Manifesto. This manifesto is dedicated to one of the most important numbers in mathematics, perhaps the most important: the circle constant relating the circumference of a circle to its linear dimension. For millennia, the circle has been considered the most perfect of shapes, and the circle constant captures the geometry of the circle in a single number. Of course, the traditional choice of circle constant is π—but, as mathematician Bob Palais notes in his delightful article “π Is Wrong!”,1 π is wrong. It’s time to set things right.

Why is Pi wrong? Among the arguments is that Tau is the ration of a circumference to the radius of a circle and defining circles by their radius is more natural and that Pi is a 2-factor number but with Tau everything is based of a single unit–three quarters of a turn around a Tau-defined circle is simply three quarters of a Tau radian.

Watch the video above to see the Tau sequence (which begins 6.2831853071…) turned into a musical composition. For more information about Tau hit up the link below to read the manifesto.

The Tau Manifesto [TauDay]

Jason Fitzpatrick is warranty-voiding DIYer and all around geek. When he's not documenting mods and hacks he's doing his best to make sure a generation of college students graduate knowing they should put their pants on one leg at a time and go on to greatness, just like Bruce Dickinson. You can follow him on if you'd like.

  • Published 06/28/11

Comments (6)

  1. NathanBaxter

    Lovely piece. Totally lost on the maths angle…but the fact that Tau visually resembles a youthful usurper giving the finger to its crippled predecessor Pi should provide an early metaphor for teachers of the next load of potential Einstein’s.

  2. Urichhai

    I likes PI

  3. Mijail Todorovich

    Ahhh… It’s that time of the year again :)

  4. Homer


  5. Steven Torrey

    Couldn’t a musical composition be written around Pi, as well? I understand Pi–what could be simpler than the radius of a circle, the diameter of a circle, the circumference of a circle? What does Tau represent?

    Second, and equally important: did the writer of this piece inend ‘ratio’ but wrote ‘ration’ which confuses the whole topic? Further, instead of “…and that Pi is a 2 factor number…” why not start a new sentence: Further, Pi is a 2 factor number… This makes for greater clarity. A paragraph wants clarity so the reader can follow the logical sequence of the thought. Just saying.

  6. tommy2rs

    I always had trouble with the whole pi r squared concept anyway. After all pi are round, cornbread are square.

Enter Your Email Here to Get Access for Free:

Go check your email!