My language is not English and i have got some problem in terminology . In physics , what's the meaning of "convert" ? Somewhere like Wikipedia claims that mass is not converted to energy since mass and energy can not be destroyed but Elsewhere claims that Energy can be converted into matter According to above it's necessary to destroying energy to converted it into matter and this is a violate of energy conversation . Hence , i think "matter can be converted into energy" is a right term since matter can be destroyed but "energy can be converted into matter" is a wrong term and is better to say "energy can be created matter" . How off am i ? In an academic view which of these are OK ?