Every casual math enthusiast has by now heard of the raging war between tau and pi.
The what?
Ok, I mean, tau’s gaining a little ground, but really, pi has the weight of history behind it, so “raging” and “war” might be overstating things a little. The point is that 3.14, et cetera, is a bad circle constant and there’s a more intuitive option, “tau.”
Take a 90-degree angle. In radians, it’s half pi, but one quarter tau makes much more sense:

If we call 2 times pi “tau,” this slice is one quarter, and things just make more sense.
Doesn’t seem to be catching on.
Not really, no. And tau has some problems too: for example τ=2π, but the tau glyph has only one leg and pi has two, so it looks like pi is twice tau. Shouldn’t tau have four legs? Clearly, the problem is this symbol: we need something more familiar. How about we just redefine pi to be twice itself?
Madness. Only confusion and chaos can result.
But not if we change the spelling. We’ll say that pie = 2pi.
Mathematicians will never go for it.
Perhaps, but food-based math has rich history. If you’re worried that it lacks a succinct one-character symbol, well, that’s where Unicode comes into the picture. In 2017, we finally have pie emoji, 🥧.