Every year on March Fourteenth people around the world celebrate the most famous mathematical constant: the ratio of the length of the circumference of a circle to its diameter. This is an irrational number, approximated to 3.14 (or 3.1415926) and represented by the Greek letter π. As a number, π is transcendental and real as well as irrational. Mathematician James Glaisher remarked of π that “a complete account of its calculation would almost amount to a history of mathematics.” (Quoted in: William Dunham, The Genius of Euler: Reflections on His Life and Work: On the History of Euler’s Constant (The Mathematical Association of America, 2007), p. 147.)

π has been calculated out to over a trillion decimal places, but we still do not know where it ends! Competitions to recite the known sequence of digits are held regularly around the world. (See pi-world-ranking-list.com for record-setting recitations.)

Mathematician Mark Kac noted that “pi, so intimately connected with circles, keeps cropping up in probability theory and statistics, the two disciplines which deal with randomness and luck.” (Mark Kac, Enigmas of Chance: An Autobiography: The Search for the Meaning of Independence (Harper & Row, 1985), p. 55.) We have an activity set up for you to experience this, based on Buffon’s Needle, the proof named after Georges-Louis LeClerc, Comte de Buffon, a scientist who enjoyed gambling.

The Greek letter π is pronounced like our English word “pie” – hence the puns, since pie is usually made in a circular pan, and, being a delicious pastry, may be difficult to divide fairly, as memorialized in the old English nursery rhyme:

A was once an Apple pie; B bit it; C cut it; D dealt it; E eat it; F fought for it; G got it; H had it; I inspected it; J joined it; K kept it; L longed for it; M mourned for it; N nodded at it; O opened it; P peeped in it; Q quartered it; R ran for it; S stole it; T took it; U upset it; V viewed it; W wanted it; X, Y, Z, and ampersand, all wished for a piece in hand.

March Fourteenth is also the birthday of Albert Einstein (b. 1879), who theorized what is perhaps the most famous equation using a constant in our universe: the relationship of mass to energy, represented by E=mc² (E=energy; m=mass; c=the speed of light).

March Fourteenth is the death anniversary of another famous physicist: Stephen Hawking (d. 2018) who developed theories about the origins of our universe, and black holes, based on Einstein’s work.

The Library is displaying books by and about Einstein and Hawking, plus books on number theory and pastries, this month.

Come on in for some Pi!