Originally Posted by Linkster

He used the speed of light in space - not the speed of light in a lab with atoms cooled to slow down the light - so the constant still works - not that it really matters because the E=mc2 isnt all together a correct statement anyway - but based on replies here I better not go into why - suffice it to say that the equation works with the matter known at the nuclear level - there have been many discoveries of smaller particles since then which while obeying the law of conservation - have other losses that weren't accounted for in that equation - if youre real interested - search for "binding energy"