σx|x>=+|x> σx|-x>=-|-x> These equations also follows for σy and σz corresponds states |y> and |z>. if we measure along axis X then X state vector let it go which means up spin and opposite not go through which means down spin. and also same for y and z axis. But, σx|u>=|d> σx|d>=|u> σy|u>=i|d> σy|d>=-i|u> σz|u>=|u> σz|d>=-|d> these 3 equations cant make any sense to me. i cant draw any physical meaning to these equations. here 1st equation shows if up spin electron goes through along X axis then after measurement spin wilbe down.but this up electron has to be up for any specific axis??right?? without axis up down is unmeaningfull.isn't it??