Dark energy = Vacuum energy???? I am working on giving a presentation on dark energy and its possible relation to vacuum energy (i.e. one and the same). I have complied information from a couple of books, as well as websites (Scientific American, NASA, Astrophysical Journal). As i understand, dark energy is this force which opposes gravity, causing the Universe to expand at an accelerated rate. I guess my blunder lies in attempting to connect the implications of dark energy to vacuum-energy (zero-point energy). What i gather, vacuum energy can be observed via the Casimir effect. I also understand that this vacuum energy describes "empty space" to have a ground state. How are these two creatures (i.e. dark energy and vacuum energy) related? Any insight is appreciated, and a preemptive thank you to whomever can shed any light on this matter.