Rafael Bombelli first used them and at the time they were thought to be useless. with other discplines (notably physics) finding a use for 'imaginary' numbers, why wasn't it's use curtailed? afterall if I was paid to fill a room with a 1000 people and could only manage 500. would i be within my rights to tell my employer when they ask, that the 500 missing guests, are imaginary. In my mind the whole SUSY theory is tainted by this crude use of mathemathics. are proponents for and against this stance?