Hi, I am fairly new to superconductivity (introductory college level). I have covered and grasped the basics but was wondering if someone could shed some light on what specifically causes materials to have zero resistance when they become superconducting. I know that cooper pairs form when the material is in a low energy state (10-100 kelvin). These cooper pairs have integer spins meaning they form composite bosons. The lattice vibrational energy (phonons) are also bosons. But what is it about these quantum mechanical effects that specifically causes zero resistance to arise? Does it have something to do with Pauli's Exclusion Principle as i have seen that some websites mention this but do not explain its significance in superconductivity?