However, a more important pie — perhaps the most important — is actually one you can’t eat at all.
And that’s pi. Or 3.14.
Once referred to in Medieval Latin by the literal and highly understated description, “the quantity, which when the diameter is multiplied by it, yields the circumference,” Pi is one of the most fascinating numbers in all of mathematics and a delicious accompaniment to any summer conversation.
At its simplest, pi is the ratio of a circle’s diameter to its circumference. The fact that you can take any circle from the tiny head of a pin to UY Scuti — the largest known star in the universe — divide its distance across by its distance around, and get the same number (pi), is mind-boggling in and of itself.
But, why might someone want to find that ratio? Well, think back to high school geometry. You often need the ratio to determine the dimensions of any shape.
However, pi’s utility goes far beyond circles and spheres. It’s critical to calculating countless mathematical equations and is used extensively in engineering, astronomy and architecture, even playing a role in discrediting the work of a detective in the O.J. Simpson trial.
This numerical constant, which the Babylonians first estimated nearly 4000 years ago to three decimal places, has now been calculated to over 100 trillion digits by a supercomputer, and it is still going as we speak. Because pi is an irrational number (a decimal that goes on forever and never repeats), the supercomputer’s calculating power could grow exponentially, and we will never be able to know all of its digits.
Reviewing the history of the concept pi is a glimpse into the astounding achievements and broader intellectual development of earlier civilizations. Shortly after the Babylonians used 3.125 to calculate the area of a circle by multiplying it by the square of its radius, the ancient Egyptians approximated the same constant at 3.1605, documented in the famed Rhind Papyrus. In fact, according to FactRetriever, many Egyptologists believe that the Egyptians intentionally made the ratio of the Pyramid of Giza’s height to its base identical to the ratio of a circle’s diameter to its circumference (i.e., pi!).
It wasn’t until more than a millennium later that we have evidence of a more detailed calculation when the heralded Greek mathematician, Archimedes, attempted to find the area of a circle by employing the Pythagorean Theorem. Without going into too much detail, Archimedes showed that pi is between 3 1/7 and 3 10/71. He knew he hadn’t found the exact number, but this was an exceptionally close approximation. More detailed work utilizing Archimedes’ approach was done over the proceeding 2,000 years, with Johann Heinrich proving in 1767 that pi is irrational and thus can never fully be known.
Although the arduous work of calculating pi from scratch is no longer necessary given the advent of computers, the number itself has developed a cult following in the modern era. Pi day, March 14th (3/14) is recognized and celebrated throughout the world. People celebrate with pie and by holding pi digit recitation contests. The current official world record stands at 70,030 digits recited by Suresh Kumar Sharma in 2015.
So, this summer, when you find yourself enjoying a nice piece of rhubarb or apple pie, remember to drop that final ‘e,’ and reflect on its more important cousin.