I searched because I didn't want to add yet another light speed question. Here's what I've been wondering about. the meter is defined now by meters per second of the speed of light so that a meter is 1/299,729,458 of a sec. since these measurements are based upon a tangent space then the topology is curved near a gravitational body. once the light moves out into open space if it's flat then contraction occurs in the measurement. as the distance increases and the light encounters another gravitational body then it's a curved manifold and to maintain the constant it would increase. this introduces 2nd order curvature yes? then when light encounters this gravitational potential the use of the schwarzschild metric determines the curvature of the space time. is not the meter already conformed to a gravitational potential? so is it that with any gravitational fields in similarity to the defined value would be regarded as unchanged? How do you then calculate the potential between flat and curved? I look at it in that in order to set the frame it requires a rotation. so we have a distant solar system, the light we receive based upon the motion and intervals and the frequency by it's color. Ok here's the paradox to me: But isn't this all assumed on the rest mass of photon to be 0 with a 1 spin? if it has zero mass then the frequency would be zero and the wavelength would be everywhere and nowhere. ??? the setting to a photon of zero mass negates any frequency change induced by gravity, but wouldn't the gravitational effect on the frequency also change the photon energy and that has BIG implications. but the current theories use the zero mass photon with angular momentum. when that photon is stripped of it's energy trying to move past the event horizon you're left with no photon and 1 spin, how? conservation of momentum is violated if you get rid of the spin right? Ughh this makes my head spin. back to the meter distance as a function of the speed of light, it's seems like a cheat to remove external frame distance measurement in order to avoid contradictions.