Today is 3.14, the day that many math nerds and bakers join forces to make pie for Pi Day. If you’ve been longing to recite the 50+ decimal places of pi or whip up a pineapple pie, this is your moment to shine. Here at KCRW, the date has long been on the “Good Food” calendar. If you’re new here, you may not know that we are more than a bit pie obsessed, looking for any excuse to taste a bite of pie for all its tasty puns and purposes. (If you don’t believe us, check out KCRW’s annual “Good Food” pie contest and Evan Kleiman’s Pie-A-Day blog posts.) This year however, 3.14 moved us to consider the notion that Pi Day might be glorifying a ratio that doesn’t live up to all the hype.
Everyone remembers from high school trigonometry. We poured over its properties and heralded it as the imperative ratio of a circle’s circumference to its diameter. You might also recall hating circles and being perpetually confused. But don’t beat yourself up over it! Perhaps our teachers just explained it to us all wrong. The ratio is correct and is used to define beautiful things like Euler’s formula. To put it as simply as possible, π = C/2r = 3.14159… in radians, = 180°. In every equation that includes π/2, we are referring to two half circles. That muddies up the magic of mathematical simplicity.
Michael Hartl puts it this way in his book “The Tau Manifesto”: “Using pi is like having a weird car whose odometer and speedometer display half-miles and half-miles-per-hour, while all the road signs show miles and miles-per-hour.” Hartl is a proponent of a movement suggesting we use the ratio τ = C/r = 6.28 in place of 2π symbolize the full circle. When we use τ/2, it is a half circle, and τ /4, it is a quarter of a circle. Now how can you get more intuitive than that!?
If you’re still with me, you’re just as into numbers as I am and I suggest you watch the following YouTube series from mathemusician Vi Hart to learn more about tau and other pi-related perils.
Though I think we need to celebrate the beauty of food and math throughout the year, I also believe we need to reevaluate our current educational curriculum to give tau more love. So I, for one, will be back on Tau Day, 6.28, to share my favorite tau(rt)s. Until then, Happy Pi Day from the “Good Food” team!