Okay suppose there is an hypothetical particle called Nelectron which has mass = mass of electron but is electrically neutral. It has same spin and other quantum mechanical properties. Even the same size (I know we don't know electron's size but bear with me) Would they bend space-time by the same amount (w.r.t. a particular observer if they move with the same velocity w.r.t. that observer) ? I read somewhere energy is ability to do stuff. What stuff? Spinning , punching , thinking , jumping . Even existence itself! Basically does the existence of charge(not mass!) Count as energy ?
PS : Can charge exist without mass ? We know masses without charges (higgs?)