Time is a flat circle, Matthew McConaughey tells us, neglecting to explain how then we could measure time's circumference to derive its diameter, using pi. (Maybe it's best not to take the sentiment ...

Times may change on a dime in our tumultuous world, but one thing always remains the same: pi, the irrational-mathematical constant, the ol’ circumference/diameter split, the big 3.14159265358979323….