π Day

Caption: The circumference divided by the diameter, that's what we're talking about.

Image credit: Kjoonlee/Wikimedia

I almost missed it again, but it's Pi Day, the day when we celebrate one of the most fundamental constants of mathematics, π (pi). Pi is, of course the constant used to calculate the circumference of a circle from its radius. When you're making a wheel or a gear, that's a good thing to know, if you don't want to waste a lot of time and materials.

Still, figuring out π's value was no easy task. It took some of the most clever abstract thinkers of ancient times. Wikipedia describes it this way:

π is an irrational number, meaning that it cannot be written as the ratio of two integers. π is also a transcendental number, meaning that there is no polynomial with rational coefficients for which π is a root. An important consequence of the transcendence of π is the fact that it is not constructible.

Wikipedia: Pi: Irrationality and transcendence

It wasn't easy. But if people hadn't tried to figure out the size of this funny number, we wouldn't be able to do a great many things today, like calculate orbits of planets, cut gears precisely, or make heads or tails of electromagnetic waves.

So, happy π day.