As moonchild posted, I was only saying that you can't measure the position of an electron exactly. I was not saying that you can't measure any properties of ele

As moonchild posted, I was only saying that you can't measure the position of an electron exactly. I was not saying that you can't measure any properties of electrons at all. The more general statement is that you can't measure exact values for any observable with a continuous spectrum; you can only measure that a quantum system is within some finite range of values. Spin has a discrete spectrum, so you can measure exact values for spin.