Energy/mass of Quantum Vacuum So far as we have measured the volume of the universe, has anyone calculated the virtual energy/mass of the Quantum Vacuum? If so, what? Or if not, a local volume such as 1 cubic meter?
This relates to steady state universal theory.
 A: According to the current and successful Lambda-CDM model of cosmology (which has a level of acceptance among cosmologists similar to that of the Standard Model among particle physicists), the energy density of the vacuum is $5.4\times 10^{-10}\,\text{J/m}^3$ and remains constant as the universe expands.
This is "dark energy", unassociated with any real particles. It has been causing the expansion of the universe to accelerate for the last five billion years or so. It is 69.1% of the current total energy density of the universe. The total energy includes this dark energy, plus the energy of all matter (both visible matter and “dark matter”) and radiation.
Its numerical value is determined by fitting the Lambda-CDM model to precise observations of the cosmic microwave background.
The theoretical reason why the vacuum has this particular value for its energy density is unknown. Some physicists think it comes from vacuum fluctuations of quantum fields, but it is hard not to get a value 120 orders of magnitude larger! Other physicists think it may simply be a "cosmological constant" $\Lambda$, the leading curvature-to-the-zeroth-power term in the Einstein-Hilbert action. If so, it would be similar in status to Newton's gravitational constant $G$, which appears in the next-order curvature-to-the-first-power term.
