Thursday marks National Pi Day in the United States and around the world. The holiday celebrates a timeless symbol cherished by many in mathematical and scientific communities, while embracing the opportunities it provides for playful wordplay, indulging in desserts, and creating "teachable moments," as some experts have mentioned.
What is pi?
Pi is a unique number — so unique, in fact, that most people are likely familiar with it, even if only as a remnant of past classroom lessons or geometry textbooks. Represented by the somewhat recognizable sequence 3.14, pi, or the Greek letter π, is an iconic symbol found in mathematical equations and, more recently, on merchandise like T-shirts, sweatshirts, and coffee mugs.
Essentially, pi is a ratio that signifies the relationship between the circumference and the diameter of a circle. If you were to trace the outline of a circle, unwind it, and then measure its length, that would be the circumference. The length of a line drawn straight through the center of a circle to its edges is known as the diameter. Dividing the circumference by the diameter of any circle will always result in pi — a constant value that holds true for all circles, regardless of their size.
Pi: The Universal Constant
Pi, denoted by the symbol π, is a constant that remains unchanged regardless of its circumstances. Its value is approximately 3.14, with an infinite and non-repeating sequence of digits following it. Despite its endless nature, enthusiasts have dedicated time to memorizing and reciting as many decimal places of pi as possible, with the Guinness World Record standing at an impressive 70,000 digits.
Significance of Pi
Math and science enthusiasts hold pi in high regard due to its essential role in a wide range of equations. This ratio is crucial for calculating the area and volume of circular and spherical objects, enabling measurements at both the microscopic and cosmic scales. From estimating the size of molecules to studying celestial bodies and even aiding in spacecraft construction by NASA engineers, pi plays a fundamental role in our understanding of the universe and its gravitational forces.
Insight from a Professor
Manil Suri, a mathematics and statistics professor at the University of Maryland, Baltimore County, emphasizes that pi offers valuable insights into the workings of our world and the universe at large. It serves as a cornerstone for comprehending the fundamental principles that govern our reality.
"The concept that all circles share a constant ratio between their circumference and diameter is truly fascinating. This unchanging number, Pi, reflects the consistent laws that govern the universe. As a mathematician, it's remarkable to think that regardless of our existence or the units of measurement we use, Pi remains the same. It's a profound realization," said Suri.
According to Daniel Ullman, a mathematics professor at George Washington University, Pi frequently emerges unexpectedly in solutions to a wide range of mathematical problems. Ullman described Pi as "an amazing curiosity" and emphasized its ubiquity in diverse mathematical contexts.
"Rather than pondering the importance of Pi, I find it more intriguing to consider its pervasive presence across seemingly unrelated scenarios," Ullman remarked. "The sheer recurrence of this number in various settings is what makes it truly fascinating."
What is Pi Day?
Pi Day is observed annually on March 14th, a date chosen due to its numerical representation of the first three digits of π. (In 2015, Pi Day was especially significant as the date aligned with π up to five digits: 3.1415.) Interestingly, March 14th also marks the birthday of renowned physicist Albert Einstein.
People and civilizations have known about pi for thousands of years, with evidence indicating an approximated measurement was used by the ancient Babylonians and ancient Egyptians. The first calculation of pi was done by Archimedes, a legendary mathematician of the ancient world, in the centuries leading up to the common era.
But the holiday did not come to be until 1988. It was founded by physicist Larry Shaw, who at the time was on staff at the Exploratorium, a science museum in San Francisco. It began at an Exploratorium staff retreat in Monterey, California, which Shaw and his colleagues took to mark three years since the death of Robert Oppenheimer, who founded the Exploratorium. Shaw drew the connection between 3.14 and March 14 during that retreat, and the first informal Pi Day was celebrated that same year at the museum to honor Oppenheimer's memory.
Pi Day became a nationally recognized in the U.S. decades later, thanks to a binding resolution passed by the House of Representatives on March 12, 2009, designating March 14 as National Pi Day.
How to celebrate Pi Day
As an official Pi Day website suggests, eating pie, baking pie and perhaps observing the mathematical principles of pi using a pie are some thematic activities to enjoy. Pizza pies and dessert pies are both appropriate variations. A play on traditional "pie contests," pi contests are common on Pi Day and often involve competitions to recite as many digits of π as possible from memory.
But there are no right or wrong ways to celebrate Pi Day. For enthusiasts worldwide who are captivated by the mathematical significance of pi and the vast potential for playful puns associated with it, there are numerous ways to show reverence. This sentiment extends to educators and students as well, with math and science professionals generally recommending leveraging Pi Day festivities as opportunities to inject more enjoyment into learning. To mark the occasion, the Children's Museum of Houston will host its 14th annual pie fight, where children can engage in a pie-throwing extravaganza using shaving cream pies in a designated area on the street.
While it's recognized that traditional Pi Day celebrations often stray from the mathematical constant, enthusiasts emphasize the importance of embracing the festive spirit. Suri, a math enthusiast, encourages educators to fully embrace the fun holiday and suggests incorporating pie into their lessons on Pi Day.
"Whenever I have a lecture on Pi Day, that's the way to go," he shared. "I would recommend it to all professors. Bring a pie. Your audience will appreciate it and engage more attentively with your lectures."
