## Celebrate the infinite life of Pi!9 min read

Reading Time: 6 minutesToday, is Pi Day. No, not the apple or cherry kind, but the kind that involves using your brain rather than your mouth. Pi, or π, is a mathematical concept – possibly the most famous concept that has fascinated people for ages. But what exactly does π mean, and where did the concept originate?

Though also a letter in the Greek alphabet, the 16^{th} one to be precise, in mathematics and physics, π represents a very special number. This special number is the ratio of a circle’s circumference (the distance around the edge of a circle) to its diameter (the distance from one edge of the circle to the other, measuring straight through the centre). This number, however big or small the circle being measured, is always **3.14159**. Confused why? Owliver is going to help you understand what π is all about.

To figure out the concept, let’s go on a journey through time, back to how π originated, and how people celebrate this day.

**Why March 14?**

Before we get into the math and physics of it, let’s understand why Pi Day is celebrated on March 14. Interestingly, it is because the date is written as 3/14. Since 3, 1, and 4 are the first three digits of π, March 14 became the obvious pick.

**Pi for the ages! **

Since Pi is basically the measurement of a circle, and circles can be found everywhere, it’s no wonder that people have been calculating this figure for eons. The earliest estimates made to calculate this figure goes back 4,000 years – back to ancient Egypt and Babylonia. A Babylonian clay artifact was discovered that dated back to 1900 BC, which demonstrated Pi to be 3.125, while an Egyptian papyrus from 1650 BC placed the number at 3.1605.

Later, in around 250 BC, the Greek mathematician Archimedes came up with a geometry-based approach using an algorithm to arrive at Pi, and found that this constant can be used to calculate the surface area and volume of a sphere.

Then, in around 480 AD, the Chinese mathematician Zu Chonghzi, used a method different from Archimedes’, and managed to calculate Pi to 3.141592920. For the next 800 years, Chonghzi’s estimate was regarded the most accurate.

Moving ahead, by the end of the 17^{th} Century, new methods to calculate Pi started to emerge in Europe. Sir Isaac Newton used a method called binomial theorem to calculate 16 decimal places. In India, in the 20^{th} Century, mathematician Srinivasa Ramanujan came up with more efficient ways of calculating Pi, which were later used in computer algorithms.

In more recent times, the advent of computers has allowed math lovers to calculate Pi to very high levels of accuracy, far beyond anything Archimedes could have ever have imagined!

For example, in November 2011, Peter Trueb successfully calculated the constant to a world-record 22,459,157,718,361 (twenty-two trillion, four hundred fifty-nine billion, one hundred fifty-seven million, seven hundred eighteen thousand, three hundred sixty-one) figures using a special program called y-cruncher.

#### Owliver’s Obscure Facts

**The first 100 digits of pi are**: 3.14159 26535 89793 23846 26433 83279 50288 41971 69399 37510 58209 74944 59230 78164 06286 20899 86280 34825 34211 7067!!

### Real-life applications of Pi

As circles can be found everywhere in nature, the applications of Pi are vast and countless. Let’s look at some ways in which the constant helps people in daily life:

**Astrophysics & Astronomy – **Pi was used by early astronomers to study the Earth and its rotation, as well as its orbits. Pi even helps in searching for new planets and their atmospheres outside our solar system. NASA uses Pi to calculate the trajectory of a spacecraft.

**Sound & Light – Sound and light are made up of waves. **Pi is found in sine waves that is used for signal processing in sound and light waves. These sound waves have numerous applications in our day to day life. Pi can be helpful in studying the way springs bounce, pendulums swing and strings vibrate. Another important application of these sound waves is in taking an ultrasound of a baby in the womb. It also helps in studying the behaviour of ocean waves. Pi comes into play even when we are talking over phone, watching television or listening to the radio.

**Genetics – **Did you know that Pi can be found within our body? Pi is found in the most basic structure of human body – the DNA.

**Construction and architecture – **Pi plays an important role in construction and architecture. Since Pi is associated with circles, anything with curvature has Pi like pillars, wires and pipes used in construction. Pi was even found in the measurements of the Great Pyramid of

Giza in Egypt!

**Literary works – **Now this is interesting.** **Many people have tried to learn the digits of Pi using mnemonic techniques. They decipher the digits into words using the same number of letters. This form of constrained writing is called ‘Pilish’, in which the digits of the number Pi matches the length of consecutive words.

**Nature – **Anything which has a diameter and a circumference can have Pi applied to it. Pi can be found in the rainbow, in the moon, in the sun, in the pupil of the eye and even in a falling raindrop. Pi has been used to measure the way a river meanders. If we measure the total length of any river in the world and divide by its straight route from its source to mouth, it averages to Pi.

### How is Pi Day celebrated?

The day was recognised in 1988 by physicist Larry Shaw as he organised a large-scale celebration at the San Francisco Exploratorium in the United States. In 2019, UNESCO’s 40th General Conference decided to observe Pi Day as the International Day of Mathematics. People all around the world celebrate Pi Day by indulging in various activities.

#### Owliver’s Obscure Facts

This year, Instagram has added a new set of custom stickers to celebrate women in tech, science, engineering and maths (STEM) as part of Pi Day. The stickers were designed by artist Amanda Phingbodhipakkiya, and aim to highlight the various achievements of women in science and tech-based disciplines.

Many organise pie baking competitions, others host challenges to memorise the digits of Pi, schools and education gives each other the fun challenge of memorising the digits of Pi after the decimal point and by computationally calculating more and more digits. Schools and education institutes observe this day by playing fun games in order to make children fall in love with the world of math.

#### Owliver’s Obscure Facts

Pi Day coincides with the birth anniversary of scientist Albert Einstein. Also, widely renowned theoretical physicist Stephen Hawking died on this day in 2018.

### Think with Owliver

Take a compass and draw a circle. Now, get a piece of string and place it on top of the circle once around. Straighten out the string – its length is called the circumference. Grab a compass and draw a circle. Now, take a piece of string and place it on top of the circle, exactly once around. Now, straighten out the string – its length is called the circumference of the circle. Measure the circumference with a ruler, and then the diameter. The diameter is the length from any point of the circle, straight through its centre, to another point of the circle. The next step is to divide the circumference of the circle with its diameter.

When you arrive at the answer, let us know in the comments below!

*Illustration: Rehna Kareem. Rehna is a freelance illustrator and an integral part of Team Owliver, who doodles at Paper Planes Doodles*

*Sources: Newsweek.com, NDTV, Brittanica, Live Science, math solutions.com*

*Photos: Wikipedia, slate.com, Giphy*