Over the last couple of weeks, food has been a top thought in our minds. The stereotypical Thanksgiving meal: turkey, stuffing, mashed potatoes, and who could forget, PIE!! Pie is very important because it is the dessert that concludes the feast, but we cannot forget about the other one: pi. The number 3.14159265[…], better known as pi, has a history dating way back to 1900 BC. Now, you may be thinking, “What’s the point of learning about the past? We’re in the future.” But to quote Fae Myenne Ng, “Remembering the past gives power to the present.” So here is a brief history of pi (the mathematical one, not the one you eat.)
“An invention has to make sense in the world it finishes in, not in the world it started.” – Tim O’Reilly
It all started 4000 years ago with the Babylonians, arguably the most advanced land based civilization of their time. In 2000 BC, they attempted to calculate the area of a circle by multiplying the square of its radius by three, which gave them reason to believe pi = 3. However, a Babylonian tablet from around 1900 BC shows that after further mathematical study they eventually found a value of 3.125 for pi, which is a closer approximation than their first finding.
Then again, what is a discovery without progress. The ancient Egyptians created The Rhind Papyrus, a sheet of mathematical formulas and theorems, in 1650 BC. This papyrus shows that they calculated the area of a circle with a formula that gave the approximate value of 3.1605 for pi. Close, but that’s not where we are right now.
“Progress is not inevitable. It’s up to us to create it.” – Michael Bloomberg
Archimedes of Syracuse, one of the greatest mathematicians of his time, was able to approximate the area of a circle by inscribing regular polygons inside of it and measuring the values of the polygons. With this method, he found the value of pi to be 22/7 or approximately 3.1418. With a vast amount of knowledge, a tad bit of efficiency, and a dash of patience, Archimedes was able to find the most approximate value of pi, by far.
Over the years, Chinese, Arab, and Indian mathematicians tried to extend the decimal placement of pi. By the early 1900s, about 500 digits of pi were known. Thanks to computers and algorithms, we now know pi to 31,415,926,535,897 decimal places!
But none of those early mathematicians tried to improve Archimedes’ method. Since the 17th century, however, mathematicians like Sir Isaac Newton and Srinivasa Ramanujan have developed more efficient ways of calculating pi. In fact, some of those more modern methods are now used in computer algorithms.
“No competition, no progress.” – Bela Karolyi
Another Chinese mathematician and astronomer, Zu Chongzhi, figured out an accurate value for pi, as well, but in a different method than Archimedes. Unfortunately, his book was lost so little is known about his work. From what we do know, Chongzhi calculated the ratio of the circumference of a circle to its diameter to be 355/113 or 3.14159292. To achieve this level of accuracy, experts think that he started out by inscribing a regular 24,576-gon and had to perform lengthy, yet precise, calculations with large amounts of square roots to up to 9 decimal places!
Isaac Newton (portrait)
“Words have meaning and names have power.” – Miguel De Cervantes Saavedra
In the 1700s, people started using the Greek letter 𝜋 (p) to symbolize pi. First introduced by William Jones, a Welsh mathematician, in 1706, Leonard Euler popularized the use of the symbol when he adopted it in 1737. The reason that the Greek letter ‘p’ was selected is that pi is the first letter in the Greek word perimitros, translated as perimeter. Ever since then, 𝜋 has been the universal symbol for pi.
So, in the aftermath of Thanksgiving, when you take a look at the leftovers of the pumpkin pie in the fridge (the one you eat), take a measuring tape, measure the diameter of the pie, divide it by 2 to find the radius, and use the formula: 𝜋 × r2 = A (pi × radius2 = Area). Congratulations, you have now found the area of the top of your pie, using pi!