In 1905 when Einstein presented special relativity it was treated as incomplete by the theoretical physicist of the day, because potentials were not included in the energy relation. A decade later with the introduction of general relativity the problem of potentials in special relativity were still not resolved. The key issue were two very different electrostatic and gravitational that could not be treated in the same way. Better experiments were needed to define the spaces matter occupied before special relativity could be integrated with the current quantum mechanics.