Monday, March 16, 2015

Pi and Judaism

BELATEDLY FOR PI DAY 2015: The Secret Jewish History of Pi. Examining the Allure of a Magic Number From the Talmud to Maimonides to Mr. Spock (Seth Rogovoy, The Forward). Only it isn't actually secret. Excerpt:
The relationship between a circle’s diameter — a line running straight through cutting it into two equal halves — and its circumference — the distance around the circle – was originally mentioned in the Hebrew Book of Kings in reference to a ritual pool in King Solomon’s Temple. The relevant verse (1 Kings 7:23) states that the diameter of the pool was ten cubits and the circumference 30 cubits. In other words, the Bible rounds off Pi to about three, as if to say that’s good enough for horseshoes and swimming pools.

Later on, the rabbis of the Mishnah and the Talmud, who knew that the one-third ratio wasn’t completely accurate, had a field day with the Bible having played fast and loose with the facts, arguing in their characteristic manner that of course it depended on whether you measured the pool from the inside or the outside of the vessel’s wall. They also had fun with some of the Gematria – the numerical value – of the words in the original passage, which when you play around with them a bit indeed come a lot closer to the value of Pi, spelling it out to several decimal points.
Last year's Pi Day post, which covers some of the same ground, is here. And more on Aronofsky's movie Pi is here.