Stern-Gerlach (1922)

Shot silver atoms through a slit then a magnetic field and observing the splitting on a screen. This is due to the fact that the magnetic moment is collinear with the Spin of the atom. The dual slits implied that the spin is quantized rather than continuous. \(\vec{\mu}=\frac{e}{m_ec}\vec{S},W=-\vec{\mu}\cdot\vec{B},F=\mu_z\frac{\partial B_z}{\partial z}\).

Results showed that spin states are discrete by the dual band of Silver atoms from the spin up and down states.