A wide-ranging review of the origins and successes of Relativity, both Special and General, is undertaken. The Michelson-Morley (M-M) experiment is briefly examined and the properties of the ether' that this suggested is noted. These properties are then re-examined in conjunction with a developing branch of physics, Stochastic Electro-Dynamics (SED). SED physics emphasizes a real, not virtual, vacuum Zero Point Energy (ZPE). Our knowledge of how the vacuum ZPE behaves fulfils all the criteria required by the M-M experiment. Furthermore, it is shown that the main predictions of Einstein's Special and General Relativity easily emerge using SED physics and the ZPE. These results are obtained with simple mathematics and intuitive concepts rather than the elaborate reasoning and difficult equations that Einstein required. A deeper understanding of the nature of mass and gravity emerges from the SED equations, along with some insights into gravity waves and their speed. A suggested explanation, involving both the SED approach and plasma physics, is given for the lack of gravitational lensing of stars near the object at the center of our galaxy.
