## Why Pi?

On this special Pi Day, 3.14.15, I thought it would be appropriate to ask the question I always love to ask, Why? Why Pi? Why Pi Day? Why all the fuss? No number is more famous than pi. But why, exactly?

Defined as the ratio of the circumference of a circle to its diameter, pi, or in symbol form, *π*,* *seems a simple enough concept. But it turns out to be an “irrational number,” meaning its exact value is inherently unknowable. Ancient mathematicians apparently found the concept of irrationality completely maddening. It struck them as an affront to the omniscience of God, for how could the Almighty know everything if numbers exist that are inherently unknowable? Pi (π) is the ratio of the circumference of a circle to its diameter. It doesn’t matter how big or small the circle is – the ratio stays the same. Properties like this that stay the same when you change other attributes are called constants.

The symbol pi has only been used in a mathematical sense since the mid-18th century. For those of you who weren’t in Greek life in college, π is the Greek symbol for the letter “p.” Oh, to go back to fraternity life!!! It was taken from the Greek word for “perimeter.”

Historically, Pi Day was started by Larry Shaw, a physicist who started celebrating Pi Day at the San Francisco Exploratorium in 1988. It was his idea to celebrate the day by eating pies and marching around circular spaces. In 2009 House Resolution 224 of the first session of the U.S. 111th Congress was passed, designating every March 14 as a day to encourage “schools and educators to observe the day with appropriate activities that teach students about Pi and engage them about the study of mathematics.” Wouldn’t Albert Einstein be proud?

**Knowledge is limited. Imagination encircles the world. — Albert Einstein**

Speaking of Albert Einstein. March 14 is not only easy to remember, it has the added bonus of being the birthday of Albert Einstein, born in 1879 in Ulm, Germany. Happy 136th birthday, Albert! Einstein did not discover Pi, but he shares his birthday with Pi Day. Einstein’s life in science and mathematics started early, with him writing his first scientific paper when he was only a teenager. In 1905, Einstein published several influential works, tackling such topics as relativity and introducing his most famous equation on mass and energy E=mc2. And, in 1921, he earned the Nobel Prize in physics.

No one is really sure who should be credited with discovering Pi. The Babylonians estimated pi to be about 25/8 (3.125), while the Egyptians estimated it to be about 256/81 (roughly 3.16). The Ancient Greek mathematician Archimedes of Syracuse (287-212 BC) is largely considered to be the first to calculate an accurate estimation of the value of Pi. It is also interesting that an approximation of Pi is used in the Bible. The approximate ratio for Pi appears in the Bible in 1 Kings 7:23:

“And he made a molten sea, ten cubits from the one brim to the other: it was round all about, and his height was five cubits: and a line of thirty cubits did compass it round about.”

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