What Time Is It In The Universe?

I've always had problems with Einstein's Speed of light constant until this explanation. Very good but my comment is that the formula would probably work just as well if we changed the constant to one of the other variables.. It's just that the Sun being the center of our solar system works better mathematically than the Earth as center. So the Speed of light becomes the constant, or am I wrong? MOK

All that wibbily wobbly timey wimey stuff.