This is kind of similar to those troll science threads, but what am I missing here? What if those energy-to-mass and mass-to-energy converters can reach 99.999% efficiency when converting to electricity to mass and vice versa in the future? Those converters are theoretically possible, aren't they? Note, this is obviously an oversimplified diagram. The wires are simply meant to represent the transfer of energy from one area to another, in this case, from an area of lower gravitational potential to an area of higher gravitational potential.