Thank you! About your last equation, wouldn't J/m^2/s^2 come out as kg? 7.9E2 would be very low then, no? I wonder how much energy is stored electromagnetical

Thank you! About your last equation, wouldn't J/m^2/s^2 come out as kg? 7.9E2 would be very low then, no? I wonder how much energy is stored electromagnetically and through nuclear forces though. These things are supposed to have extremely strong EM fields and I imagine every piled up nucleus like a little atomic spring that has been depressed as much as possible. Wouldn't most of the stored energy be in there?