### Historical Entry—Monday, March 14, 1988

Pi Day (also sometimes shown as π Day) was first celebrated at the San Francisco Exploratorium in 1988. Larry Shaw, a physicist working at the museum, set out to celebrate the famous number on March 14, or 3/14, which he saw as similar to the beginning of π, 3.14.

The first celebration kicked off at 1:59, the next three numbers in the sequence, bringing the day’s value to 3/14 1:59. It included a table filled with fruit pies and a tea urn. A few years later, Sara, Larry’s daughter, noted the day was Albert Einstein’s birthday (born 1879), adding another science-oriented fact to the day. Later celebrations included walking in a line 3.14 times around the Pi shrine to the music of “Pomp and Circumstance” with the digits of pi added as vocals. The marchers sing “Happy Birthday” to Albert Einstein while marching.

On March 12, 2009, when the U.S. House of Representatives passed the non-binding resolution 111 H. Res. 224 which recognized March 14 as National Pi Day. The day has been even more widely observed in the last ten years, with many pizza restaurants offering discounts on their circular wares. Grocery stores and supermarkets have also joined in this trend with many offering bakery pies for $3.14.

Pi was thought to be first discovered by the Babylonians. They calculated a circle's area being three times its radius's square. This gave the first version of pi a value of 3. A tablet was discovered dating from between 1900-1680 BC which gave the indicated value of pi as 3.125.

In 1858, a Scottish antiquarian purchased what became known as the Rhind Mathematical Papyrus in Luxor, Egypt. The papyrus had been copied by the scribe Ahmes from a text written during the reign of Amenemhat III. Dating places the papyrus around 1550 BC. It contained three mathematical books. Book II-Geometry included the value of pi as 3.1605.

Both of these values were approximated, not true calculations. Archimedes of Syracuse (287-212 BC) used the Pythagorean Theorem to determine the area of two regular polygons. One was inside the circle, the other outside. Since the actual area of the circle is between the areas of the inside and outside polygons, he was able to calculate the value of pi between 3-1/7 (3.14286) and 3-10/71 (3.12408).

Four hundred years later, the mathematician and astronomer Zu Chongzhi (429-501 AD) used another method to calculate the value. What method he used is lost to time since the book he wrote has not been discovered. However, other works reference his and his calculated value of 355/113 (3.14159).

In 1706, William Jones introduced the idea of using the Greek letter π to represent the value. In 1737, Leonhard Euler adopted the idea and popularized it in his writings.

On 19 August 2021, a team of Swiss researchers calculated the most accurate value of pi currently known with a whopping 62,831,853,071,796 (about 62.8 trillion) digits. The calculation was performed at DAViS (Centre for Data Analytics, Visualisation and Simulation) using the software y-cruncher on a computer running Ubuntu 20.04. It seems someone is always getting around to a more accurate answer for this famous value.

Pi Day/π Day

Historical Event

1988

This Day in Science Fiction History examines notable events, real and fictional, concerning fantasy and science fiction in various media.

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