Ahoy hoy...I'm having some trouble understanding exactly where the momentum operator comes from. The momentum operator is P=-ih/(2*pi)*d/dx I know that according to the DeBroglie relation p=kh/(2*pi) and in the first chapter of my book we introduce the operator K=-id/dx which is hermitian (which is necessary for getting real eigenvalues). So they say in the book that the P opertor is just P=hK/(2*pi)...but I don't see why. Is there some sort of relation between the wave # k and the operator K? When I asked my professor all he said was something about the units of K being right, but I don't even see that. Any help would be greatly appreciated.