Liverpool One Wheel/Wikipedia
The number pi is the ratio between a circle’s diameter and its circumference. Typically ballparked at 3.14, it remains the same for a circle ringing the universe and a circle ringing a molecule of oxygen. That’s amazing, and humans have been obsessed with the number for as long as it’s been around, which is since about 1650 BC or possibly even earlier, depending on whether or not you buy the idea that Egyptian pyramid-builders were intentionally using the proportions of a circle (probably not). By 1630 AD mathematicians had successfully reached 39 digits of pi, using an approximation technique involving many-sided polygons. As of 2011, we’ve successfully reached about 10 trillion digits.
In January of 1897, the state of Indiana voted on whether or not to truncate pi to a simple “3.” It was an exquisitely misguided attempt not to make life easier for early-days industrial era engineers, but to rebel against the abhorrent concept of an irrational number. According to the Straight Dope (via), Edward J. Goodwin, an amateur mathematician, took a bunch of different bad measurements of circles and diameters, coming up with pi ratios ranging from 4 to 3.2. Goodwin argued that the 3.14 … figure was “misleading.” If his measurements couldn’t settle on one value—despite the success of the entire history of mathematics on doing so—we should just all abide by one, semi-arbitrary number and be done with it.
The bill died not because someone pointed out that using "3" just wouldn’t work because it’s drastically different than the correct real world value and everything would break, but because …
The bill was postponed indefinitely and died a quiet death. According to a local newspaper, however, "Although the bill was not acted on favorably no one who spoke against it intimated that there was anything wrong with the theories it advances. All of the Senators who spoke on the bill admitted that they were ignorant of the merits of the proposition. It was simply regarded as not being a subject for legislation."
In any case, pi is pretty easy to measure just with a tape measure and circle with a diameter of one (one inch, foot, meter, anything). Mark a point on some circle/wheel right where it touches the ground, wheel the circle around until that point touches the ground again and measure the length between the two spots on the ground where that point on the wheel touched. That’s pi, a constant number for eternity. It’s really that easy and amazing.