Pi is one of our oldest and most recognizable math accomplishments. Fancy-pants mathematicians think we should move away from using it because there are numerous counter-intuitive features of Pi as the math gets more advanced. Tau v. Pi is a battle to reconceptualize circle math in terms of motion rather than in terms of solids.
There is a simple historical reason for Pi working the way it does: Euclid does not employ radius as a term in his Elements, only diameter. On that system Pi is the ratio of the perimeter over the diameter, and so the perimeter of a circle is πd. As we pressed on in circle math we found that radius was a useful, even powerful, element and so was born our standard reliance on radius (think area of a circle or volume of a sphere, but it gets more advanced from there very quickly).
I’ve been in a puckish mood for a while–blame the midnight diapers–so instead of showing an educational video about Tau, here’s a low-brow death battle between a Tau Separatist and a Pi Partisan.
Tau v. Pi is a very interesting dispute that goes far beyond what squiggly symbols we use in 8th grade formulas. There’s a lot of text and video out there for a very worthwhile reflection on what exactly circle math is all about.