Why does in QM the electron does not fall toward the nucleus? After all, the only force between nucleus and electron is attractive. It seems that the electron can and does indeed fall toward the center in <simple harmonic oscillator>? My question is what's so different in these two systems that cause two different results? It seems that the argument in the FAQ would fail in the case of s.h.o. If that's the case, does it mean the argument is wrong in the first place?