By Spontaneous emission it is said that the electron jumps to the higher energy state and then after some time "spontaneously" falls to the lower state. It is still not clear to me, what makes the electron to "fall" back to the lower state, if higher state is also allowed state and excitation does not violate transition rules, therefore "spontaneously" falling contradicts 1 Newton's law, or it is due to the acting Columb's forces and interactions between electrons in the atom? And what determines time at which electron stays at excited state, I assume it is somehow Fermi statistics? I am in a master level. Thank you.