How Pi Almost Wasn't

Since you’re reading this essay, you probably already know about the mathematical holiday called Pi Day held on March 14th of each year in honor of the mystical quantity π = 3.14…. Pi isn’t just a universal constant; it’s trans-universal in the sense that, even in an alternate universe with a different geometry than ours, conscious beings who wondered1 about the integral of sqrt(1–x2) from x = –1 to x = 1 would still get — well, not 3.14…, but exactly half of it, or 1.57…. Therein lies a catch in the universality of pi: why should 3.14… be deemed more fundamental than 1.57… or other naturally-occurring2 pi-related quantities? I suspect that, even if we limit attention to planets in our own universe harboring intelligent beings that divide their years into something like months and their months into something like days, many of those worlds won’t celebrate the number pi on the fourteenth day of the third month. It’s not just because 3.14 is a very decimal-centric approximation to pi (i ... Read full article.