Hi all, this my first forum ever. I'm a self taught physicist. So pardon my ignorance. I pose this question. If speed :s = distance :d ÷ by time :t Then how can we possibly measure our cosmos accurately with a measure of speed aka "Light Speed". The problem I see with this is TIME is a variable is the speed equation that changes throughout the cosmos/space-time. For example. Time Dilation. Since we know that gravity effects light. As it pulls light into a black hole. If light were to move past a large object, let's say a star. Then gravitational time dilation would speed light up as it left the stars gravity as observed from the star. "Relative velocity time dilation" would also slows down light as it speeds past an observer. Now multiply that by the light traveling across billions of objects like stars, planets, black holes even by galaxies over millions of years. How accurate can our "light speed measuring stick" possibly be at that point. This also raises another question. If we want to go faster than light we must first understand what the actual speed is in a control with all gravity taken out of that equation. It also may be lights Achilles heel. A way for us to beat it. I obviously understand that we are susceptible to time dilation too so the whole faster than light debate will be for another day. Today I pose this question and a statement, if the fastest thing in the universe is not as fast as we think it is or even faster and we use it to measure the cosmos, our entire understanding of the size our universe will grow or shrink with it.