Electrons in an atom interact with the nucleus through the electromagnetic force via the exchange of massless photons (γ). The weak force is mediated by Z0 bosons. The weak effects by themselves are too small to see directly. However, it is possible to measure the effect of Z0 boson exchange between an electron and a neutron by looking at the quantum mechanical interference between this process (right) and the electromagnetic interaction (left). The figure provides a pictorial representation of how the quantum interference between the two processes—the sum of the amplitudes squared—contributes to a measureable signal.