United States Postal Service ‘Special Relativity’ Issue 1916
Following the publication of Albert Einstein’s ‘Special Relativity’ paper of 1905 and the subsequent ‘General Theory of Relativity’ in 1916 the US Post Office intended to release a postage stamp celebrating these discoveries. The 10-cent ultramarine series 1902 bicycle messenger design was adapted with Einstein’s famous equation prominently incorporated into the artwork, together with a rewording of the stamp from the original ‘Special Delivery’ to ‘Special Relativity’. The series is also dated 1916.
Unfortunately an over enthusiastic type-setter included a 3 and not a 2 resulting in the incorrect equation being reproduced on the stamp (instead of E = mc² the issue read E = mc³). Although an extra dimension might be useful the post office decided to correct this with the addition of a +2c (2 cents) over print which obscured, to some extent, the offending number 3. This led to a humorous interpretation on the part of some physicists consulted by the Postal Service on the original design who dubbed the intended issue the ‘AE’ IOU (AE being Albert Einstein’s initials). As the stamp was immediately withdrawn few examples now survive and none are known to be in private collections.