What does the "c" in E=mc squared stand for?

Question

I know that the formula E=mc squared means "Energy equals mass times the speed of light squared.", but what does the "c" stand for?

Answer 1

E = mc^2 simply says that invariant rest mass, m, is stored energy, E.



And if there were such a thing as 100% efficiency the amount of energy we can get just happens to be the value of the speed of light squared, c^2, time the amount of mass, m, we would be converting into energy, E.



Lest there be a misunderstanding. Even though c is the speed of light, nothing in the equation is moving. c^2 is just a multiplier, a very huge constant of proportionality. m, the mass, is not moving; in fact we often call it rest mass because it is at rest.

Answer 2

The speed of light, as you stated clearly in the question.

Answer 3

c means the speed of light, it comes from "celeritas", the latin word for "speed"