# The Center of Math Blog

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## Thursday, March 17, 2016

### St. Patrick's Day

Happy St.Patrick's                                                          Day
Legend has it that Saint Patrick's day involves the shamrock, or a three leaf clover. After St. Patrick trained as a priest and bishop he traveled Ireland in 432AD with a goal to convert the pagan Celts who inhabited the Island. Having previously lived there, he was aware that the number three held a special significance in Celtic tradition, and pagan beliefs. Essentially as a technique to convert the pagan Celts, he used the shamrock to explain the Christian concept of the Holy Trinity.

Apart from the religious aspects of this day, many in Ireland and other Western nations use St. Patrick's as an excuse to drink and attend their city's parade. With so many websites focusing on the science of beer on St. Patricks day, the Center would like to reference Matthew Francis science blog, Galileo's Pendulum. The article discusses one of Ireland's greatest mathematicians, William Rowan Hamilton, and one of his great discoveries.

In 1843, he was walking along the Royal Canal in Dublin in deep thought regarding complex numbers and if they could be extended to higher dimensions. Once he realized they could be he carved his solution on the Brougham Bridge. The Plaque shown on the right commemorates his discovery.

The equation he carved on the Brougham Bridge is:

For physics enthusiasts: Hamilton is also the man who discovered Hamiltonian dynamic, which in turn underlies quantum mechanics and several aspects of chaos theory.

To better understand this solution, remember that an imaginary number is the square root of a negative real number. A real number, includes all counting numbers, negative numbers, ratios and irrational numbers, like π that can't be expressed as fractions. The imaginary unit is the square root of -1. Complex numbers are the sum of a real number and an imaginary number.

In the spirit of St. Patrick's day the Center interviewed a fellow Irish employee, Ruairi Collins!

Q: What is your favorite St. Patricks day memory in Ireland?
A: As a kid each village had a bag pipe band. I loved watching them perform on the streets with my friends. Also, St. Paddy's day was during lent, so we were allowed to eat some of the candy we were saving up for Easter Sunday.

Q: Whats the main difference between how the holiday is celebrated in the United States and in Ireland?
A: Since St. Paddy's day is a national holiday in Ireland, no one goes to work or school. Also, the older community in Ireland sees it as more of a religious holiday and will attend church.

Q: What is the legend of the leprechaun?
A: No idea - it's an American tourist thing!

Q: Are there any St. Patrick's day themed problems the Center has been working on?
A: Yes this is one for the American audience!