I was thinking the other day, and I thought about how light travels in circles. If you look at a candle in the dark, you see a small circle of light; the sun emits light in a sphere, and so on. So if light works in a circle, then how come it is E=MC^2, and not something like E = m c π r 4, which is how you find the surface area of a sphere? (Where 'π' = Pi, r = radius, and the others remain unchnged)

Could you please explain to me if I am wrong, and if so then how?