People love π to the point of worship. There are t-shirts with the π symbol made up of digits of π. There are people who memorize thousands of digits. There’s a Google-recognized holiday dedicated to eating round things (especially, um, pie). Modern civilization was built on π. And yet.
And yet there is a resistance against π, small, but growing. It can be found lurking in the back alleys of the Internet, sometimes discussed in lecture halls, but more often talked of secretly in small, windowless rooms, also known as graduate student offices. It’s the kind of thing that has a manifesto – because all good resistance movements need a manifesto – and I have to admit, I see it. π might very well be wrong.
First, a middle school math refresher: π (pi) is the circle constant, an irrational number (i.e., one that can’t be expressed as a fraction) that is often rounded to 3.14. Pi is the ratio of the circumference of a circle, or distance around, to the diameter, or distance across. The issue with pi, argue its opponents, is that the diameter is not the most natural choice for that ratio. Rather, they prefer to use the radius, or the distance from the center of the circle to the edge. The π opponents propose using a new ratio of the circumference to the radius, calling it τ (tau). Since the diameter of a circle is twice the radius, τ = 2π.
Perhaps some of you are thinking, as I did upon first hearing about τ, something along the lines of, “Who the hell cares? It’s a factor of 2. Learn how to use a calculator, if it bothers you that much.” But as I started reading The Tau Manifesto, I must admit that I began to side with the τ-ists.
The first critical hit in my faithfulness to π came with a discussion of the angle measure of radians, or a ratio between the length of a part of a circle to the radius. A turn of 180 degrees, for example, is half of a circle, and equivalent to π radians; a full turn of 360 degrees is equivalent to … oh. 2π radians. τ radians. Thus, 7/8 of a turn is 7τ/8 radians, and 95/163 of a turn is 95τ/163 radians. Could I reject such evidence of τ’s superiority?
And the dismantling of my faith in π continued. Even in the area formula, π times the radius squared, my belief was undermined when the Manifesto pointed out all of the other formulas of similar form to τ times radius squared divided by 2- the distance something travels in free fall under the influence of gravity, the energy of motion of an object, the energy stored in a stretched spring. I couldn’t deny it any longer. π is wrong. τ is the way.
Unfortunately, I’m not quite sure what to do with my new knowledge. π may be wrong, but it’s also the standard. Before I start preaching of the virtues of τ to my classes, I need to make sure that I am not alone.
So I come to you, likely believers of π, and I ask that you give τ a chance. Read (or watch, or listen to) The Tau Manifesto, and see if you don’t also fall under its spell.