No one has answered your question. There is no answer really to your question. At least, not to the level that you are asking. Why is c^2 in that equation? What does it mean? We don&#x27;t know. It&#x27;s a deeper level of understanding that we haven&#x27;t achieved.<p>Another similar question would be why does pi come up in everything? There&#x27;s a lot of physics where pi comes up and we don&#x27;t know why.