### Celebrating Pi Day 2019

Today is Pi Day, so oh, go ahead, plan to have some Pie. They are made from fruit, and therefore nutritious and the perfect breakfast food… right?

So what’s all the fuss? Well, Pi, the number, kind of makes the world go ‘round. Pi is defined as measurements relating to circles – it is the ratio of the circumference of a circle to its diameter – so it is a part of all kinds of formulas in trigonometry and geometry, especially those involving spheres. It’s also used in cosmology (think Carl Sagan), statistics, thermodynamics, mechanics and electromagnetism. And Pi is definitely the big man on campus when it comes to popularity as it’s the most widely known math constant both among scientists and regular folks like us. Take anything round, the wheel of a car, or a tabletop… and divide the length around by the length across, and you get Pi. Always. No matter what the measurements.

Pi is an irrational number, meaning it goes on forever without end and without the numbers repeating. Mathematicians have been trying to calculate pi (it is a decimal that goes on to infinity – okay, that’s mind-blowing) for thousands of years. In the 15th century, a new algorithm was developed that helped to calculate it much further out than ever before, but in the 20th-century invention of the computer extended the calculation of this modest little number out to 10 trillion digits. But that’s mostly just for bragging rights since most practical formulas using pi only need to go to 40 places to be useful.

Pi isn’t just for science – it’s been adopted for use everywhere in our culture.

In the novel Contact, the author (Carl Sagan – coincidence?) suggested the creator of the universe buried a message for mankind within the digits.

In a science museum in Paris a circular room known as the “pi room” has 707 digits of pi inscribed on the walls.

In 2011, Google used a factor of pi to come up with its bids on a technology portfolio it purchased at auction.

Some other interesting things about Pi –

Albert Einstein was born on Pi Day in 1879.

Stephen Hawking died on Pi Day in 2018.

The number “Pi” was named back in 1706 using the Greek letter Pi, or P in the Greek alphabet.

If you hold a mirror up to the number 3.14, the reverse image spells “PIE” in the reflection.

National Pi Day (March 14) should not be confused with National Pie Day (January 23).

So whether you are a pi lover or a pie lover, take a moment tomorrow to enjoy a bit of both and appreciate how pi (and pie) make the world go ‘round.