Ah yes - I did mean conservation of mass, thank you. I think most people use 'matter' to refer to the regular objects we interact with that are composed of ato

Ah yes - I did mean conservation of mass, thank you. I think most people use 'matter' to refer to the regular objects we interact with that are composed of atoms, and that's how I intended to use it in the above post. However, if I had my way, electromagnetic radiation would also be consider 'matter', because it's the same stuff, just a different form. >> As energy has mass Is that generally accepted, btw? Because I've always heard people talk about light as having no mass, and it never made sense, because that what I understood e=mc^2 to represent. I think it does have mass, it's just so minute (smaller than anything we know by such an order of magnitude that the speed of light squared is used to express it) that it doesn't seem like it.