The "Vacuum Energy" is fictitious. I have bad news for the nice folks who thought that by clapping our hands together we could have free energy from the vacuum. The vacuum energy is an artifact of the way the Casimir Effect is described. Here are three websites that have good descriptions of the effect. http://www.physics.adelaide.edu.au/~dkoks/Faq/Quantum/casimir.html http://physicsweb.org/article/world/15/9/6 http://focus.aps.org/story/v2/st28 They describe an attractive force between two perfectly reflective plates that goes as: F=pi2h-bar*CA/240r4 where A is the area and r is the separation between the plates. The problem with assuming that the energy involved is "in the vacuum" is that it completely omits the question of the energy used to make the surfaces of the plates. Note that while the force varies as the inverse fourth power, the energy varies as the inverse third power. So we should think of the energy as asociated with a field of virtual photons emanating from the surface of the plates, and the Casimir Effect as being due to a kind of distance dependent surface tension, whereas ordinary surface tension, whch has the dimensions of energy divided by area, is independent of distance.