In countries that write it that way, today's date is 3/14/15 which matches up with the first five digits of pi, 3.1415…at 9:26:53 the date and time matched up with the first 10 digits of pi, 3.141592653. As Jeffrey S. Rosenthal points out here there's even a more magic moment…BTW, the last Pi moment "better" than today, was 3/14/1592 at 6:53:58 (12 digits).
It's difficult to celebrate that pi instant moment, but the special pi day is celebrated. It won't happen again before 2115.
Pi is magical in the sense that the closer you look the more digits you see…forever…and its irrational (per mathematical definition) in the sense that there is no answer to the question: how often does the string "1415" repeat in the decimal fraction of pi?
Working with pi in practical quantitative systems you use it as symbol or put it into a box…use it precise "enough". But automated precision control in a complex algorithm needs a lot of knowledge about the transitiveness of inaccuracy of nested functions and operations…
The magic of irrational numbers is at the heart of each difficult, quantitative work. In general. You make a specification that puts a "box" around your future work. But the spec changes (in reaction to market dynamics) and you need more "digits"…
This is how we think at UnRisk…this is how we have designed it: quant developers and us always need more precision at speed, more models, more methodologies, more data…for more magic work.
