Pi day graphic
By Katie Stannard
Did you know that Saturday, March 13 is Pi Day Eve? Are you familiar with Pi Day, its significance and observances? Are you thinking, say what? Or are you all set with your Pi Day plans?
Pi Day refers to the annual celebration of all things pi-related on March 14—as in 3/14, as in 3.14—as in the numerical equivalent of pi: 3.14 (rounded off!). But what is pi? What is Pi Day? Today’s Science Saturday circles around to explore the mysteries and fun of both!
A quick roundabout into mathematics will help our understanding. Pi is the ratio of the circumference of a circle to its diameter. No matter the size of the circle, the ratio remains the same—it is always pi. In an ever-changing world, how ideal to have a constant! 
In numerical form, pi is also special, as it’s a never-ending, non-repeating number. In mathematics, this is called an irrational number. Mathematicians first became aware of pi’s importance by 2000 B.C. Today’s mathematicians have calculated pi to 6 billion digits!
According to Scientific American magazine, the Greek letter π was first used in 1706 by William Jones, and adopted 30 years later as the common abbreviation, or standard mathematical notation. It’s utilized in computations involving circles, circumference, diameter, the area of a circle and many more applications in physics and mathematics. Does that spark a recollection of memorizing formulas? Who not currently practicing mathematics recalls circumference = 2 x pi x radius, or 2πr? Or that a circle’s area = pi x the radius squared?
a series of pi's
From Pi to Pi Day
Larger-scale, cultural observances of Pi Day began in 1988, originating at San Francisco’s Exploratorium science museum. Festivities included a march in a circle, then the eating of pie. (Get it? March in march?) In 2009, The House of Representatives passed a non-binding resolution supporting the designation of Pi Day. The resolution highlighted the importance of math and science programs, and encouraged “schools and educators to observe the day with appropriate activities that teach students about Pi and engage them about the study of mathematics.” UNESCO, the United Nations Educational, Scientific and Cultural Organization, named March 14, Pi Day, as the International Day of Mathematics in 2019.
Pi Day celebrations include pie-throwing, walking or running 3.14 miles, competitions to recite pi to many decimal places and of course, eating pie or pizza, to name a few. It is said that the Massachusetts Institute of Technology makes their admissions acceptances available on March 14. According to nationaltoday.com, 6% of Americans have memorized pi to more than 10 digits, 2% of Americans have a pi tattoo, and 15% wish there were a pi emoji. PiDay.org features teacher resources and a countdown clock to the magical day. BTW–Another reason for amping up the celebration factor: March 14 is also Albert Einstein’s birthday.
einstein graphic
While we at Matthaei-Nichols may join in pie-eating and overall general pie appreciation, we may also admire and appreciate all things round in nature: like the wood cookies featured in our photo, round rocks, growth rings, stems, branches, mushrooms, rain drops, seeds, flowers, planets, and more! (One might ask, why are so many things in nature round or spherical? Stay tuned for a subsequent Science Saturday story on the subject!
tree cookie sequence
Why pi and not tau?
But pi and Pi Day are not without some controversy. What, you say, can be wrong with pi and pie? Not pie, but how pi is utilized in computations. The core of the argument is that the ratio of circumference to diameter is simply not as relevant in mathematics, compared to the more frequent use of the radius or r as utilized in equations about circles. Beyond its use in circles, there are many more complex applications in math–and most everything in trigonometry–which involve pi. But–and here’s the kicker–a majority of those involve 2 times pi as the constant, or 2π, which is symbolized by the Greek letter tau, or T. Tau is approximately 6.28 (2 times pi) and represents the ratio between circumference and radius, known as the circle constant. 
So, the pro-tau camp–known as the tauists (!) have compiled lengthy lists of important physics and mathematical equations in which 2π figures centrally. “If 2π is the perennial theme, the almost magically recurring number across myriad branches of mathematics, shouldn’t that be the fundamental constant we name and celebrate?” queried Randyn Bartholomew in Scientific American. 
We don’t have an answer to that, but we’ll circle back around to it on June 28, otherwise known as Tau Day (6.28=2 times 3.14)! As tauists proclaim, tau day offers twice the pi(e)!
In the meantime, how are you acknowledging Pi Day? Pie, cookies, circular things, circular logic, drawing circles? Share your thoughts in Facebook comments!
Sources: https://www.scientificamerican.com/article/what-is-pi-and-how-did-it-originate/, https://www.scientificamerican.com/article/let-s-use-tau-it-s-easier-than-pi/, https://www.piday.org/, https://nationaltoday.com/national-pi-day/
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