Two electrons can exist close together if they have opposite spins, but this does not negate the electromagnetic repulsion between them. The wave function for electrons with anti-parallel spins is higher in energy compared to those with parallel spins, leading to a tendency for electrons to avoid each other due to spin correlation. In superconductivity, however, electrons can pair up, forming Cooper pairs that exhibit unique properties. This pairing allows them to overcome the usual repulsion and move through a lattice without resistance. The discussion highlights the complex interplay between spin, energy states, and electromagnetic forces in quantum physics.