Third thread same topic. Non physicist asks question-why speed of light squared? Answers Its the derivitive that makes the equation work. The speed of light is some kind of ultimate measuring device. You are too stupid to understand. I think the questioners are incorrectly phrasing what they actually want to know We see the realtionship between Mass and Energy almost intuitively. What we dont see is why light has anthing to do with it at all.( and dont answer-it doesnt,its the SPEED of light because saying light and the speed of light are not connected makes no sense) Some say it doesnt matter because the equation is so cool and valuable-who cares? Well, could it be that the next entire level of understanding of Physics could pivot on figuring out why these realtionships exist?