I was looking through a physics book that has the answers in the back. this is not homework. It asks about a neutral beam of hydrogen atoms going into a strong non-constant B field. It asks how many ways will the beam split. It says the answer is 2. Why is the answer not 3. spin 1, spin 0, spin -1. if we consider the spin of the proton and the spin of the electron. we should have 3 cases. both spin up, both spin down, and then opposite spins.