Hi All A question that bothering me and I can't find answer for: a charged particle in empty space will generate an electromagnetic field that has energy density and can be described by Energy-Momentum Tensor. A non charged particle at rest also has energy due to mass energy equivalence. so the total energy of our universe will be bigger if the particle is charged?! if that true please explain why there is no kind of charge/energy equivalence like for mass. But if that wrong, please explain from where our field gets the "extra" energy that it "radiates" (i.e photons) Thx in advance for helping.