We all learned pi in school in the context of circles. Pi is the ratio of a circle's circumference to its diameter. It is an irrational number approximated by 3.14. It turns out that pi shows up all over the place, not just in circles. Here is just one instance. Take a piece of paper and a stick. Draw several lines along the paper so that the lines are the length of the stick from each other. Then randomly drop the stick on the paper. The probability that the stick will land so that it cuts a line is exactly 2/pi, or about 64%. If one were to perform millions of trials, one could use the results to perform a very precise calculation of the value of pi without ever considering its relation to circles. This is just one of many places pi pops up in reality, and pi is just one of several mathematical constants that appear to be woven into the fabric of the universe. One mathematician likened it to looking out over a mountain range, where the bases of the mountains are shrouded in fog, and