This problem borders with the question of either wave only or particle only descriptions of duality, and I think it could possibly even end up being a personal opinion of the (hopefully qualified) repliers. In a normal atom, are there electrons orbiting around the nucleus? [This seems like a no-brainer: "Yes" but I don't believe that is true per QM.] Or, is there only an electron wavefunction of probable locations around the nucleus? This is to specifically ask whether there are really actual electron particles (as we would assume them to exist as fermions) each with their own velocity orbiting in an atom that is not being observed, or are there no physical electrons extant? I think QM gives wishy-washy open interpretation to this. Strictly, does QM not say that unless the electron is observed and the wavefunction collapsed, then the electron does not exist in one place with one velocity, but only probabilities of locations and velocities? But this does not jive with our idea of what fermions are.. This could be expanded to question whether fermions ever actually exist in one place in spacetime at any time other than when they are observed. (The question could be rephrased as a question regarding electrons as point particles in the double-slit experiment. When the slits are not being watched and electrons are fired individually, an interference pattern results. It seems then that the electrons go through both slits having two directional velocities, but neither one nor the other. This would mean that while the electrons were in flight they did not actually exist as fermion point particles except upon firing and being received at the end.) How then are the electrons -- if not extant as particles when not being viewed -- subject to gravitational acceleration and maintain inertia/momentum while in flight?