The creativity of the Dirac equation really struck me when I first learned it. Basically, it uses a mathematical trick to write sqrt(a^2 + b^2) = a + b, which d

The creativity of the Dirac equation really struck me when I first learned it. Basically, it uses a mathematical trick to write sqrt(a^2 + b^2) = a + b, which doesn't work for normal math, but does work if a and b anticommute: ab = -ba. You can implement this with matrices, and in the resulting solution quantum spin just pops out. Astounding.