A friend recently asked me the question, "If electrons have a negative charge and the nuclei of atoms have a positive charge, why don't electrons simply collapse into the nucleus and sit on it?".
I tried to direct him to things such as the Pauli Exclusion Principle or Heisenberg's Uncertainty Principle, calling upon him to see an electron as a space of probability densities rather than a particle, but ultimately neither did he feel satisfied nor could I give a satisfactory answer (considering especially my limited knowledge of atomic physics).
Could you give an answer for me and for him, in some detail, that explains both intuitively and with some depth why this is?
