If you slowly drop an electron onto a proton, you will form a hydrogen atom. In the lowest energy state, it's stable. Why isn't the lowest energy state an electrostatic-driven collapse of proton and electron? More specifically, which of the four fundamental forces pushes back on the electron when forced near the proton? It's not the strong, electric or gravitational forces That only leaves the weak force. But the interaction range for the weak force is much shorter than that. I assume it is a force that can store and release potential energy or it couldn't oppose the electrostatic attraction.