# Mass or Charge?

## Main Question or Discussion Point

Mass and charge are qualities of any substance found in nature. That's because they can produce fields of forces. Fields have the capability to do work so we say that energy is stored in fields.but why mass alone is a condensed form of energy as E=MC^2 suggests..why not E=qC^2 ? I mean charge and mass are similar (except for dissimilarities like charges repel and also attract and produce magnetic fields when accelerated) even charge is relativistic invariant but where as mass is relativistic variant..why is this so??
" bending space produces mass " is that true? if yes then why not charge?? or is there something besides space which on bending causes charge?? why are the laws partial with mass but not charge..

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I have not started learning any of the relativity principles..I just know that all of them are derived based on this simple fact derived by Maxwell that for a given medium the velocity of light is constant = 1/(u0 e0)^1/2...and that is irrespective of any relative motion of an observer
an observer travelling with any velocity will observe the speed of light to be constant for that medium..and from this we can derive any law of length or anything...but i dont understand how mass can be changed??
mass is a conserved quantity like charge..hm..can anyone suggest me about all this??

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hello peeyush_ali,