http://phys.org/news/2014-03-dark-energy-phantom-fields.html
Now researchers from Barcelona and Athens suggest it is the quantum vacuum which could be behind this energy that moves our universe. "What we think is happening is a dynamic effect of the quantum vacuum, a parameter that we can calculate," explained the researcher. The concept of the quantum vacuum has nothing to do with the classic notion of absolute nothingness. "Nothing is more 'full' than the quantum vacuum since it is full of fluctuations that contribute fundamentally to the values that we observe and measure," SolĂ pointed out. These scientists propose that dark energy is a type of dynamical quantum vacuum energy that acts in the accelerated expansion of our universe. This is in contrast to the traditional static vacuum energy or cosmological constant.