EVE General Discussion

The sun's rays' energy gets converted to heat, not to mass. Energy as it stands does not have mass. Einstein's equation provides for destroying a ton of energy energy and creating a little raw mass, or destroying mass and getting a lot of energy out of it.

The only thing it means is that "creating something from nothing" is possible, but would require a hell of a lot of energy input. Similarly, a conversion bomb (sci-fi weapon for now at least) would be utterly devastating -- converting a human being to pure energy would destroy most of the solar system in the ensuing burst.