No, imamartian was not right, because matter can be created from energy.Yes that is right, the total amount of matter and energy in the universe is constant.I learnt in my school physics lessons that matter cannot be created or destroyed...
You're dangerously close to being correct there.Yes matter and energy are interchangeable, but matter is neither created or destroyed, by the process.You weren't listening then, because I was told, and am repeatedly reminded by (amongst other sources) populist TV science magazines, that matter and energy are interchangeable.