When we first learn Dirac notation (the bra and ket thing to represent state vectors), the notation for the inner product becomes so succinct.
But why? Why does it become so succinct? I know there are a lot of questions that are meaningless or they need not have an answer for the theory to work but there should be an explanation for it. Is there a theory or something deep inside that makes it work. Or it is a mere coincidence.
Are there other such notations that promise to make the notations look more succinct like the Dirac notation or is it unique?
