Happy birthday of set theory, for all those who celebrate!

On December 7, 1873, Georg Cantor (https://en.wikipedia.org/wiki/Georg_Cantor) wrote a letter (https://www.aleph1.info/?call=Puc&permalink=cd1_Briefe_Z4) to Richard Dedekind in which he showed that there are more real numbers than integers and that therefore different kinds of infinity exist. Cantor's proof at this time is not the “diagonalisation” proof that is now usually given.

December 7, 1873 is also the 50th birthday of Leopold Kronecker (https://en.wikipedia.org/wiki/Leopold_Kronecker), which is ironic, given the heavy conflicts they would have about set theory.

The birthday of set theory is usually celebrated with a birthday cake that has ℵ₀ candles on it, but you can take fewer if you don't have the space for them. 🕯️

#SetTheory #Mathematics #HistoryOfMathematics #HistoryOfScience #GeorgCantor #LeopoldKronecker