Our American colleagues celebrate today Pi Day, although, technically speaking, it is American Pi Day: for the rest of the world, today is 14/03/14. A brilliant article by Steven Strogartz in The New Yorker, a brief quote:

What distinguishes pi from all other numbers is its connection to cycles. For those of us interested in the applications of mathematics to the real world, this makes pi indispensable. Whenever we think about rhythms—processes that repeat periodically, with a fixed tempo, like a pulsing heart or a planet orbiting the sun—we inevitably encounter pi. There it is in the formula for a Fourier series: […]

Read the whole article.