My first post here, this question may have been asked before and answered already, if so a link would be appreciated. When we measure interstella distances are we measuring curved space distances or flat space distances? Putting it another way.... Are we able to determine the curvature sufficiently to measure the distance? As we use Light years as a measuring tool, velocity over distance. Do we assume flat distances or curved distances, curved distances being considerably longer than flat ones? Sorry if the question is all confused.