# Books for Pi Day

Hey everyone! It’s Pi Day! Today is the day when we celebrate that ridiculous but also irrational number you get when you divide a circle’s circumference by its diameter. I can’t tell you exactly what pi is, because it has that irrational tendency to go on forever, but I can tell you the it begins 3.1415 and HEY WILL ‘YA LOOK AT THAT IT’S TODAY’S DATE. If you think there’s something magical and fun about such weird coincidences, congratulations, that’s what math is all about. No, mathematics isn’t about plugging in equations so you can figure out how fast a train can get to Poughkeepsie. It’s about looking for patterns and finding meaning in those patterns.

Basically, if you have curves, you need pi. Pi is essential to the Golden Ratio and the Fibonacci numbers. You need it to make fractals. You’ll find pi in electromagnetism and thermodynamics. Einstein used it in his field equation, which forms the basis for his general theory of relativity. Speaking of Einstein, he was born on March 14, 1879. That makes Pi Day Einstein Day too.

Want to learn more about pi? Check out Pi: A Biography of the World’s Most Mysterious Number or The Joy of Pi. If it is your desire to teach kid’s about the wonders of pi, I recommend Sir Cumference and the Dragon of Pi or Piece of Pi: Wit-Sharpening, Brain-Bruising, Number-Crunching Activities with Pi. Would you like to learn more about how mathematicians are figuring out more and more digits of pi? Pi – Unleashed is the book for you.

Finally if you just want to celebrate without having to whip out your calculator, pi is part of the plot of Carl Sagan’s book Contact—and yes, that’s the book the Jodi Foster movie Contact is based on. There’s also Darren Aronofsky‘s debut film Pi, the experimental cult sensation about a guy who believes patterns and numbers can be seen in all things.

Finally, now that I have you all worked up about pi, check out Vi Hart’s convincing video on why we shouldn’t be celebrating pi at all.