I haven't taken the time, but I'm pretty sure the force would be too low to ever, ever be measurable. But has anyone ever measured the force of gravity, from at least an atom? I'm not meaning the effects of gravity upon the atom, I'm meaning the exertion of gravitational force from an atom, to another particle. Say you have one hydrogen atom suspended in space, you put a detector with another particle in an electric field, at a distance, the particle would sway thorwards the atom, due to gravitation(other factors calculated and taken into account). How massive does an objective have to be until you can actually start measuring it's gravitational field?