Full disclosure: I have the first 51 digits of pi tattooed on my left calf and foot, so I am personally and permanently attached to the traditional definition of pi.
|My left leg|
Pi is a fundamental constant of the universe, and it is defined to be a circle's circumference divided by its diameter, or the distance around a circle divided by the distance across it. The number pi shows up in math and physics on a regular basis, even when we are not talking about circles, and it is safe to say that without an understanding of pi, we would not be as technically advanced as we are as a species today.
But if NASA is right, we will discover alien life in the next 20 years, and while that life will probably just be microbial, as a species, we should start thinking about how we would communicate with intelligent life, should we ever find it. Math is a universal language, so it is only a matter of time before humans try to show off our intelligence by demonstrating our knowledge of pi, but... what if we are wrong?