[neutralino]

Originally Posted by MJA Thanks again RP, I find this line of thought wonderful! I am somewhat well read in the thought processes of A Einstein, but have never grasped with simplicity the purpose of squared in the equations of physics. Would you do me a great favor and try to explain C squared. I know you know. Thanks, = MJA

A simple answer is that c^2 is a conversion factor. The equation E=mc^2 says that energy is directly proportional to mass, the constant of proportionality being c^2. That is, the c^2 converts from units of mass to units of energy. As I've said here before, one can select units in which c=1 (in fact, these units are utilised quite frequently in relativity and are called geometric units), then the equation reads E=m.

The statement that RascallPuff makes above, in discussing the area of a circle as pi r^2 is not the same; namely in this case, r is a variable: the size of the circle, whereas above, c is a fundamental constant.