The Philadelphia Inquirer
Wednesday, March 13, 2002
PENNSYLVANIA COMMENTARY
Celebrating the natural beauty of the universe with Pi du jour
by Elizabeth Landau
This month we celebrate the spring equinox, the Passover seder, Good Friday, and Easter. However, there is another important tradition each March that often goes unnoticed. It is Pi Day, which we celebrate tomorrow, which happens to be 3/14.
Really, Pi Day does exist, and it has nothing to do with fruity pastries.
Falling on the birthday of Albert Einstein, Pi Day honors the most fascinating and troublesome number known to mathematicians and philosophers alike. For those of you who've gotten a bit foggy over what you learned in math--and for those who maybe never learned it-- pi is the ratio of circumference to diameter of a circle, approximately 3.14.
Pi appears in all sorts of equations describing the physical universe, particularly pertaining to circular shapes and movements. For example, the volume of a sphere is four-thirds of the cube of its radius, multiplied by pi. By simply relating the width and circumference of a circle, pi has had phenomenal consequences in all realms of knowledge, including biology and statistics.
What has immortalized this number? Perhaps it is not the answers that pi gives us to our geometry homework, but the questions it raises. How could a number so important to our universe be composed of digits that continue infinitely in an apparently random sequence? If pi is the ratio of circumference to diameter, why can't it be measured exactly through experimentation? Why isn't pi the solution to any algebraic expression?
It seems paradoxical that if pi is a ratio, it cannot be expressed as a fraction, but great mathematicians-- Leonhard Euler, Johann Heinrich Lambert, and Ferdinand von Lindemman-- proved that pi is neither rational nor algebraic. No finite fraction would ever exactly equal pi, hence it is "irrational," like the square root of two.
Understanding the elegance of pi requires nothing more than consciousness. The first humans had no textbooks or calculators, only the sun, the moon, spherical pebbles, and eyeballs. These natural circles lead them to see that the distance around one of these shapes was a bit more than three times the distance across it.
As early as 2000 B.C.E., the Babylonians determined that pi is equal to 3.125 and the Egyptians arrived at 3.56. Both cultures probably got these values by drawing a circle in the sand and measuring the distance around it with a rope. That point on the rope was then marked, and the distance across it was measured. The rest is history.
What can you do to celebrate pi? Take math homework seriously. Find out what calculus means by "approaching pi." Try memorizing a hundred digits and see if you find a pattern:
3.14159265358979323846264338327950288419716939937510582097494459230781640628620998628034825342117
Let us not dismiss Pi Day as a strange excuse for a few math nerds to discuss their favorite number. Pi Day is a national celebration of the natural beauty of the universe as well as the history of mathematics.
Elizabeth Landau runs the Web site "The world of pi" at http://members.aol.com/loosetooth/pi.html.