hi.. i wondered... is energy is something tangible? i mean.. theoretically.. is it possible, with some (theoretical maybe) test machine to test how much energy there is in a body? or is is a theoretical concept (that obviously helps solving problems, but is unmeasurable) my guess was that no the second option.. but i want to be sure.. and a second quest. there are kinds of energy, such as kinetic, which are relative to something else. is all kinds are? if so, what is electronic energy, or spring energy (kx2) are relative to?