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  • Paul Anthony Jones

Feynman Point

(n.) a series of six consecutive nines in the 762nd–767th positions of pi

illustration of the Feynman point at the 762nd digit of pi

March 14 is Pi Day, because when it’s written out numerically the date 3.14 forms the first few digits of pi. And every year over on HH, we like to mark that fact with this handy bit of trivia:

Now, we’re not mathematicians here at HH, and frankly the very idea of discussing the irrationality of an approximation of the mathematical constant representing the ratio of the circumference of a circle to its diametzzzzzzzzzzzzz…

Only joking, mathematicians, we love you really. But even bookish old wordsmiths can find some interest in mathematics every so often, and the Feynman Point is one of those times. So we thought you might like to know a little bit more about the point behind The Point.

The Feynman here is the American theoretical physicist Richard Feynman. In a lifetime of achievement and accomplishment, he did everything from helping to develop the atomic bomb to assisting in the commission that investigated the Challenger disaster in 1986. He was also one of the joint winners of the 1965 Nobel Prize for Physics for his “fundamental work in quantum electrodynamics”, including his groundbreaking work on quantum path integral formulation challenging the existing notion of a unique quantum trajectory by replacing it with a functional integralzzzzzzzzzz…

Only joking, physicists, we love you as well. But long story short, Richard Feynman was a brilliant scientist—and he was also very interested in pi.

According to mathematical legend, during a lecture at the California Institute of Technology, Feynman once joked to his students that he would like to memorize pi up to the point, 762 decimal places in, that there are six consecutive nines. Why? Well, he wanted reach that particular repdigit and then state “...999999, and so on”, implying that the famously irrational pi suddenly, after 762 decimal places, becomes nothing more than an infinite chain of 9s.

Regrettably there’s little evidence that Feynman ever actually made that joke (and in fact the earliest account of it credits it to fellow scientist Douglas Hofstader), but it’s Feynman’s name that has ended up being attached to these six consecutive 9s, and it’s his name that has remained in place ever since.

Incidentally, another six consecutive 9s crop up in the 193,034th–193,039th decimal places of pi should anyone fancy memorizing up to there. You could get your name in the dictionary if you do.

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