I just want to clear up something about electron spin to see if I have it correctly. As far as I understand it is it not really spinning but it's just a convenient word and what it denotes is the the particular quantum number is either up or down. Now I think I've got it right to say that this value is not determined until it is measured and the measurement then forces the electron to choose either up or down on the axis which it is measured. I further understand it that once the spin is measured on a particular axis that the spin on the other two axes cannot be known. What I am not sure of is if an electron has 'spin' on three different axes at once but only one can be measured and therefore known at one time. Or if it in fact it only ever has spin on a single axis and whatever axis is measured the electron then becomes either spin up or down on that axis. I hope that is clear with regards to my question.