Do you mean there are two kinds? Or if you swap any two?
This is why two fermions can’t be in the same state: if you swapped them, you’d be back where you started, but that somehow also had to phase shift 180 degrees, and the only complex amplitude that is the same as its own negation is zero.
This is why two fermions can’t be in the same state: if you swapped them, you’d be back where you started, but that somehow also had to phase shift 180 degrees, and the only complex amplitude that is the same as its own negation is zero.