As far as I am aware, E=m(c*c) is supported by all applicable experimental evidence. No experiment has ever showed it is wrong. So far as I know, anyway. Do you believe: E=m(c*c) is 100% correct, and that's it? Or do you believe: E=m(c*c) seems 10% correct, but of course there is the possibility that some day some new discovery may cause a re-think, or alteration, or the relation?