not necessarily but at least far enough away that gravitational forces are way different. the sun contrls orbits for over 1000 au but neptune I think is the farthest circular orbit at 30 au. Our measurements at 1au have no practical gravitational variance at all but we assume light is uneffected by it.
Yeah, this is a teally intresting thought! The observation should be really somewhere outside of galaxies, or where there is almost no gravitation.
not necessarily but at least far enough away that gravitational forces are way different. the sun contrls orbits for over 1000 au but neptune I think is the farthest circular orbit at 30 au. Our measurements at 1au have no practical gravitational variance at all but we assume light is uneffected by it.