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Fermi postage stamp has an error
In the April 4 Monitor story about the visit of Enrico Fermi’s granddaughter to Los Alamos, a photo of Fermi in front of a blackboard was included with no caption.
There is an interesting story about that photo, which shows on the blackboard a geometrical figure and a formula. It was taken along with a few similar poses for publicity purposes, and one of those shots eventually appeared on a U.S. stamp at a time when firstclass postage was 34 cents. The stamp photo reveals only part of the formula, but enough to discern the error.
The truly remarkable aspect of the photo is that there is an error in the formula! It is a famous equation for a fundamental physics quantity called “the fine structure constant,” which describes the strength of the force between electrically charged particles and light. It has the approximate numerical value of 1/137, and is one of the most famous numbers in physics. The fine structure constantly appears on the left side of the equation and is represented by the Greek letter alpha.
On the right side is a fraction involving three fundamental constants: the speed of light, represented by the letter c; the charge on the electron, represented by the letter e and Planck’s constant, represented by the letter h with a short bar crossing the H. The error Fermi made was to interchange the placement of the E and the H.
On paper it would be called a typographical error; I’m not sure what you call it on the blackboard.