By a curious coincidence, π day is also the birthday of Albert Einstein: He was born on march 14, 1879, in this house in Ulm in southern Germany (the house was destroyed in 1944, so you cannot visit it any more):
(Source: Albert Einstein in Ulm)
As the celebrations of his 125th birthday, and the 100th anniversary of his Annus Mirabilis have brought us many many great websites about Albert Einstein, there is no big point in repeating here anything of all you have for sure read many times.
But did you know that Einstein himself might have had some trouble to recognise PI π in his birthday? As every child learns in school in Germany, dates are written in the form day, month, year. So, Einstein has written his birthday most probably as 14. III. 79, following the conventions of his time and using roman ciphers for the month. That's good to know if you want to make sense out of the date 4. I. 19 - it is January 4th, 1919. That's no special date, it just happens that Einstein lectured about "ponderable bodies" on that day, as he has written down in his lecture notes:
(Source: Albert Einstein Online Archive)
The lecture on 9.11. (that's November 9th, quite an important date in German history) fiel aus wegen Revolution - it was was cancelled "because of revolution"...
Coming back to Einstein and the π day, one might wonder whether Einstein's papers are encoded somewhere in the decimals of π. That's the case if π is a so called normal number. Unfortunately, no one knows so far whether π is normal or not, despite ongoing progress on this question.
The inverse question is much more easy to answer: Does π occur in Einstein papers? If we have a look in the famous Ist die Trägheit eines Körpers von seinem Energieinhalt abhängig? (Annalen der Physik 18 (1905) 639, here as PDF, the famous L = mV2 paper), this paper gets by without any π! OK, you may say, that's a short paper. What about the Elektrodynamik bewegter Körper (Annalen der Physik 17 (1905) 891, here as PDF - the electrodynamics of moving bodies, the SRT paper)? Surprise, there are only 4 πs in this 30 page paper, and only in relation with one expression for the energy density. If you really want to get rich in π better invest in Über die von der molekularkinetischen Theorie der Wärme geforderte Bewegung von in ruhenden Flüssigkeiten suspendierten Teilchen (Annalen der Physik 17 (1905) 549, here as PDF, the paper about Brownian motion) - I did not count them all.
What can we learn from all this? The special theory of relativity is not transcendental!
Happy π day!
TAGS: PI day, Albert Einstein