PACS: 03.50.De, 05.10.Gg, 12.20.m.INTRODUCTIONQuantum theory predicts that the vacuum of space in the universe is filled with low-energy electromagnetic waves, random in phase and amplitude and propagating in all possible directions. This is different from the cosmic microwave background radiation and it is referred to as the electromagnetic quantum vacuum since it is the lowest state of otherwise empty space. When integrated over all frequency modes up to the Planck frequency, QP (~ 1043 Hz), this represents an enormous potential source of energy with a density of as much as ~ 10113 J/m3 which is far in excess of any other known energy source even if only an infinitesimal fraction of it is accessible. This is also several tens of orders of magnitude greater than the energy density of matter-antimatter annihilation reactions. Evenif we are constrained to integrate over all frequency modes only up to the nucleon Compton frequency (~ 1023 Hz), this energy density will still be enormous (~ 1035 J/m3). And we have not taken into account the fact that the electromagnetic quantum vacuum is not alone by itself. On the contrary, it intimately couples to the chargedparticles in the Dirac sea of particle-antiparticle pairs and thereby couples to the other interactions of the Standard Model (weak and strong force vacua). So all the numbers we just mentioned admit of some further adjustment. http://www.calphysics.org/articles/Davis_STAIF06.pdf <http://www.calphysics.org/articles/Davis_STAIF06.pdf>