rank amateur here - as i currently understand it, dark energy does not react with anything so we cannot detect it directly. DE is deduced from macro scale observations of the movements of distant galaxies, which arent behaving as they should given the amount of observed mass. (i hope all that is correct...) 1. so, if energy is defined as the ability to do work, and DE does not interact with anything, how can we call it energy? 2. DE is said to make up some 80% of the undetected mass/energy in the universe, and its main (only?) effect is the gravitational pull all the equivalent mass adds to a system - is that correct? if it is evenly distributed, how can it have any kind of local gravitational effect? 3. is there some chance that DM/DE are artifacts of some slightly incorrect aspect of General Relativity, such as the grav constant, or cosmological constant, which might be tweaked to explain the observed galactic motions? thanks.